315 lines
17 KiB
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315 lines
17 KiB
Plaintext
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| File Name : DPALMA8.ASC | Online Date : 10/31/95 |
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| Contributed by : Andrew Mount | Dir Category : ENERGY |
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| From : KeelyNet BBS | DataLine : (214) 324-3501 |
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| KeelyNet * PO BOX 870716 * Mesquite, Texas * USA * 75187 |
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| A FREE Alternative Sciences BBS sponsored by Vanguard Sciences |
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| InterNet email keelynet@ix.netcom.com (Jerry Decker) |
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| Files also available at Bill Beaty's http://www.eskimo.com/~billb |
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A very simple and cheap homopolar generator can be constructed using the
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details of the file CLARK11, available freely from KeelyNet. We have two
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KeelyNetters who report it works as described and we expect some data for
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speed vs. output in the near future as more people experiment with this small
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version. Bruce DePalma is currently living in Auckland, New Zealand as of
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1995. Andrew Mount is DePalmas secretary and assistant.
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The homopolar generator would be an ideal high current, low voltage source for
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the production of Browns gas or hydrogen to run an engine or do welding in a
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hybrid arrangement.
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If you choose to experiment in these areas, please share your findings and
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observations with KeelyNet........thanks!.......................>>> Jerry
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Released January 6, 1988
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DePalma Energy Corporation,
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1060 Channel Drive,
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Santa Barbara, CA 93108
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Two years ago the DePalma Energy Corporation initiated the construction of a
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large N machine which was scaled from smaller machines which were used to
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verify the validity of direct extraction of electrical energy from space or
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the vacuum.
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The N-1 machine was to produce a high enough output voltage so as to be
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efficiently convertible to high voltage alternating current. Target
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parameters for the machine were 12 v.d .c output at 10,000 amperes for a 6000
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r.p.m. rotational speed.
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The rotor is a key component of the N-1 generator, and into it goes most of
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the time and effort in constructing the machine. Figure (1) shows the
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completed rotor suspended from a crane. Two N-machines are connected
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electrically in series on a common shaft. Magnetic polarity is NS-SN so that
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rotation of the unit causes the voltages to be additive.
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Electrical connections are made to the outer edges via liquid metal, metallic
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mercury wetted contacts as shown in figure (2). Some of the considerations
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incorporated into the design are: The idea of series, two machines on the
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same shaft, is a good one because with magnetic polarity indicated only two
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identical mercury contacts are needed.
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The drawback is the necessity of separating the two N machines far enough from
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each other so as to reduce the demagnetizing effect of one on the other. A
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further simplification is the use of only two support bearings for two
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machines, providing the center section can be made stiff enough to place
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vibrational problems above the planned operating speed of the machine.
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The 9-1/2 inch separation of the two magnet stacks resulted in a 20% reduction
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in the field strength of the combination. Initial computer simulations of the
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field strength inside 8-3/8 inch thick, 13 inch diameter magnet stacks of
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NdFeB magnet material indicated 9000 gauss. Actual measurements gave only 3/4
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of the expected figure, 6750 gauss.
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Together with the 20% loss due to the proximity of the magnets the resultant
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field strength is 5400 gauss in the center of the stacks. We have found some
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relaxation in the strength of NdFeB magnets in open flux path operation even
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when the diameter to thickness ratio is what would normally considered to be
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a safe 2:1.
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The achievement of a field strength of 6750 gauss uniformly distributed over a
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diameter of a 13 inch circle with permanent magnets without a closed flux path
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is impressive considering the size of the water cooled electromagnet needed to
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produce the same result. Nevertheless it was felt that the flux inside the
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machine could be increased by making the machine partially self-exciting.
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This was accomplished by subdividing the 14 inch diameter by 3/8 inch thick
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copper disc in the center of each magnet stack into two parallel windings of
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two turns each. This is done in the manner of Tesla, (Reference 1).
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Since the machine is operating on the slope of the demagnetization curve of
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the magnets a small increment of magnetic induction will result in a
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disproportionate increase of the magnetic flux of the magnets. With
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sufficient current drawn from the machine the output impedance will decrease
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and may become negative.
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At present the measured internal resistance of the machine is 75 micro-ohms at
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800 amperes and the voltage output is 1.216 volts per 1000 r.p.m. Mercury
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contacts must be amalgamated by hand before assembly and seem to improve with
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running time. Mercury builds a surface layer of oxide in contact with
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atmospheric oxygen. Oxide sludge can be eliminated by operating the machine
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in an inert helium atmosphere and hermetic sealing of the unit.
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The N-1 generator incorporates both of these features which also prevent any
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leakage of mercury or mercury vapor into the environment. The rotor is
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constructed on a BeCu shaft 2 inches in diameter and 49 inches long. BeCu is
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used for strength and good electrical conductivity.
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The center section between the magnet stacks is stiffened by a 6 inch diameter
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1/2 inch wall aluminum cylinder which encloses the central axle of 2 inch
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diameter BeCu. The two central shafts are screwed together in a coupling
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which when the magnet stacks are rotated one relative to the other, tightens
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and places the aluminum cylinder in a state of compression. The stressed
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center section is stiffer than if the connection was a solid 6 inch diameter
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cylinder. All components are anodized and teflon coated so that electrical
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conduction takes place along the designed path.
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The magnet stacks themselves are constructed of 200 pieces each made from
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NdFeB hexagons of dimension 2 inches (across the flats) by 1 inch thick, pre-
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magnetized. Each magnet weighs about 1 pound. The magnets which repel each
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other intensely are assembled and glued together with proprietary adhesives.
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The assembled magnet stack is wound with 1/4 inch of graphite fiber roving
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followed by 1/4 inch of epoxy-fibreglass. As constructed the rotor should be
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capable of 10,000 r.p.m. without damage. Further development would result in
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a rotor capable of standing 20,000 r.p.m. without flying apart. The mercury
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contacts operate totally satisfactorily but are not entirely leakproof.
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A small amount of mercury is lost in the operation of the machine which
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amounts to about 1/2 c.c. per minute. A continuous flow system can be
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provided to recycle and clean the mercury.
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As can be seen from figure (2) the edge of the copper disc protrudes a
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distance slightly less than 1/2 inch into a slightly larger channel cut into a
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copper bussbar which encircles the magnet stack. The actual point of contact
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with the mercury is made at a radius determined by exploration with a Hall
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effect magnetometer. There is a point, somewhat above the surface of the
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magnet stack where the fringing field produced by the presence of the copper
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disc is exactly canceled by the flux linkages proceeding over the outer
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surface of magnet from the north to south poles. Thus the mercury sliding
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contact takes place in a region of zero flux.
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The presence of strong magnetic flux around the rotor, and its considerable
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weight, 800 lbs., make it a very difficult piece to handle mechanically. In
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movement around a machine shop for the various operations, every motion must
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be thought out carefully. After the work is finished all the tools have to be
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demagnetized, including large lathes and milling machines.
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These difficulties have to be counterbalanced by the easy accessibility of the
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liquid metal sliding contacts and the higher voltages obtainable from the
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large radius magnet stacks. Since voltage increases as the square of the
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machine radius, the loss in flux from non-closure of the flux path is more
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than compensated by the increased voltage output. i.e., if a 6 inch diameter
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central axle in a closed path machine were operated at say 2 x 6750 gauss or
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13.5 KG then the voltage obtained would be only 1/2 of what would be gotten
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with half the flux (6750 gauss) at twice the radius (12 inches).
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The other overriding consideration is that no closed flux path is possible in
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a machine operating with super-conducting magnets since the attainable
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magnetic strength, 90 KG, will saturate known magnetic conductors. Figure (3)
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shows the partially assembled machine, figure (4) shows the completed N-1
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machine under test.
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A loadbank capable of absorbing 100 KW @12 v.d.c. is in the background. Tests
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are preliminary for two reasons. Firstly we are operating at only a small
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fraction of power output for which the machine is capable, and second it is
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only possible to estimate the electro-mechanical efficiency of the drive
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motor.
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A second more definitive round of testing will take place when we have
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installed an in-line direct torque sensor between the drive motor and the N-1
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generator. The exact comparisons can be made between direct horsepower
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mechanical input and the electrical output.
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Electrical testing of motors and generators is a carefully specified procedure
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and has been followed in accord with well established engineering practice.
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The results will be presented here.
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Reference to the testing of d.c. machines: "Principles of Direct-Current
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Machines", Alexander S. Langsdorf, M.M.E., 5th ed., McGraw-Hill Book
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Co., Inc., 1940.
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The drive motor used for our experiments is a d.c. machine originally used to
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supply a constant 30 v.d.c. at up to 500 amperes in aircraft service during
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W.W. II.
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Operating speed was 4000-8000 r.p.m. and output voltage was regulated by
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control of the field excitation, nominally 24 v.d.c. @ 12 amps.
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The machine has six poles and six interpoles excited by a combination of
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armature and field currents. The voltage picked off the commutator by six
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sets of brushes passes through the interpole winding which adds 1/2 v.d.c.
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drop for each 100 amperes of armature current. The interpoles are used to
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prevent commutation losses in electrical machines operated at high speed.
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The presence of the interpoles reduces the size of main poles by about 30%
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with a consequent loss in efficiency. The complete subject is dealt with in a
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Langsdorf's book. In addition to the IR drop in the interpole winding there
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is a one volt drop assigned to each carbon brush in accord with AIEE
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procedures.
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Electromechanical efficiency of d.c. machines studied hits a maximum of about
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85% in the center of the operating range. Efficiency falls rapidly at low
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speeds and decreases much less rapidly at speeds above the maximum efficiency
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point. (See Langsdorf p. 525)
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The average of five runs on January 5, 1988 are presented. Three of the runs
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were at no load condition and two were under load. Operating speed for all
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tests was exactly 2600 rpm. Measurements were very consistent differing 1-2%
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from run to run.
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machine speed : 2600 r.p.m.
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internal resistance @ 800
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amps : 75 micro-ohms
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load resistance : .003875 ohms
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volts/1000 r.p.m.: 1.216
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Derived calculations, two loaded runs, three unloaded runs.
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motor power input loaded: 5030 watts
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unloaded : 2383
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N-1 electrical output : 2480
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(1) straight electrical efficiency (no corrections) = 93.8%
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(2) electrical efficiency corr. for brush and interpole winding drop =
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108.5%
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(3) electrical eff. corrected assuming motor electromagnetic efficiency .8 =
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136%
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(4) efficiency assuming motor eff. of .4 = 271%
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[note: What is being measured is electrical efficiency. Examination of the
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figures shows loaded input is supplying electrical output and no-load
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mechanical losses (expressed electrically). On this basis a corrected
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loaded input (case 2) of 4440 watts expresses a no-load mechanical loss
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of 2155 watts and an electrical output of 2480 watts (simultaneously).
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This gives an overall energy balance of 4440 watts input giving rise to 4635
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watts total output (sum of elec. and mech.). This expresses an overall
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efficiency for the N-1 unit of 104.5%. Without corrections for motor
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efficiency 195 extra watts have been extracted from space.]
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Set of assumptions (4) seems most likely since this figure falls into line
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with the average of power ratios reported for N machines by Trombly (4.92),
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Tewari (1.75 - 2.50), DePalma (original Sunburst machine 2.5 - 3), Kincheloe
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(improved Sunburst 4.9).
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For the calculations made on the DePalma Energy N-1 unit for the five runs
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averaged the loaded drive motor current ranged from 194 to 197 amps. Drive
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motor voltage ranged from 25.5 to 26 volts respectively.
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Unloaded drive motor current ranged from 89.5 to 96 amps voltage from 25.4 to
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25.8 volts. Loaded current output was 800 amps. @ 3.1 v.d.c.
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Unloaded d.c. output voltage ranged from 3.1 to 3.22, avg. 3.16. All readings
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taken at constant speed of 2600 r.p.m.
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Change in loading on the drive motor only changes armature current, armature
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voltage remains essentially constant.
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The next phase of measurements will refine the efficiency determination by a
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direct measurement of generator driving torque x r.p.m. from an in-line
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torque sensor. This installation will take some time however it was felt
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useful to put out an initial report since the reported results are consistent
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with the findings of other investigators.
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Many workers are attempting to construct a self-running motor generator
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combination operating on the principle of direct extraction of electrical
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energy from space. The presently used combination uses a Faraday disc motor
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excited from an N machine mounted on a common shaft.
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Even if the electro-mechanical efficiency of the Faraday disc is state of the
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art 96% the losses in the system may make it difficult to get the loop gain
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over 100%. N machine output increases as the square of the voltage or speed
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but mechanical losses consist of constant factors which are speed invariant
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and mechanical N machine output must be high enough to overshadow all the
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constant and speed variable losses.
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Examination and digestion of the parameters and figures shows it may be
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necessary to have electrical output of the N machine in the 30 - 40 kilowatt
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range before a Faraday disc N machine combination could self-sustain. A d.c.
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machine such as we are using for a drive motor has too many losses to be
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considered for a self-running combination.
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The self-running combination will probably require a drive motor with reduced
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back e.m.f. compared to the Faraday disc with the same mechanical output. For
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some years I have been advocating the use of a motor with such
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characteristics. This is covered in reference (2).
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A permanent magnet version of this machine has been built which operates and
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shows interesting characteristics. Back e.m.f. is generated in the Boning
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motor from the N effect voltage generated in the central axle which is both
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magnetized and rotating. This voltage subtracts from the applied voltage
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which is causing the motor to rotate.
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As can be appreciated from the geometry of the situation this back e.m.f. can
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be made 25% of that which would exist if a Faraday disc were used to the same
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diameter as the Boning spiral in an inside out Faraday disc motor. It is
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clear that if a principle of energy extraction is operative as an electrical
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generator, that same principle could be applied in the form of an electrical
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motor with reduced back e.m.f.
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The object to develop an N machine electrical generator of high power
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capability and useful voltage output has been realized with the N-1 unit.
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Further measurements will refine the understanding of this. Exact torque
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measurement will remove uncertainties from the exact power gain of this unit.
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Future work on the rotor will attempt to achieve high dynamic balance so the
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unit can be run at a designed speed without excessive vibration. Research on
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the self-running machine will continue with the study and further construction
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of the Boning motor. As work continues additional reports will be issued.
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The N-1 rotor unit is a manufactured item and is available from the DePalma
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Energy Corporation.
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Bruce E. DePalma,
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6 January 1988,
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Santa Barbara, California
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(1) Nikola Tesla; The Electrical Engineer, N.Y., Sept 2, 1891. Published by
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Nikola Tesla Museum, Beograd, Yugoslavia, 1956.
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(2) Wireless Engineer, November 1952, Vol. 29, No. 350.
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(3) by Paramahamsa Tewari, Dept. of Atomic Energy, Nuclear Power Board,
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Bombay, India. A high quality videotape documenting the experiments
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described in the paper will be available from DePalma Energy Corporation.
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Format NTSC or PAL
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