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*To*: tesla@xxxxxxxxxx*Subject*: RE: 3 phase converting*From*: "Tesla list" <tesla@xxxxxxxxxx>*Date*: Thu, 20 Jan 2005 18:31:22 -0700*Delivered-to*: testla@pupman.com*Delivered-to*: tesla@pupman.com*Old-return-path*: <teslalist@twfpowerelectronics.com>*Resent-date*: Thu, 20 Jan 2005 18:31:57 -0700 (MST)*Resent-from*: tesla@xxxxxxxxxx*Resent-message-id*: <D0ynsC.A.WWH.MuF8BB@poodle>*Resent-sender*: tesla-request@xxxxxxxxxx

Original poster: Harvey Norris <harvich@xxxxxxxxx>

--- Tesla list <tesla@xxxxxxxxxx> wrote:

> Original poster: "Steve Conner" > <steve.conner@xxxxxxxxxxx> > > >You can run a three phase > >motor okay, but you can't generate a true rotating > magnetic field > > That's kind of a contradiction in terms. If you > didn't have a rotating > magnetic field then by definition you would not be > able to start a three > phase motor. > > I once visited the EE department at Glasgow > university and they demonstrated > a spinning "Beer Can Of Columbus" that worked off > single phase current. It > used two coils 90 degrees apart with one fed > directly from the line and the > other fed via a capacitor. I think they used low > voltage AC like 24v or > similar. Very interesting concept there! After mulling things over it would seem that a single phase can be manipulated to appear as polyphase. In air core terms one could measure the voltage rise of the resonant coil, and then supply the reactive coil with the same voltage as a reactance coil. The magnetic fields produced would be out of phase, which is a requirement for a rotating magnetic field. Heres some further negative text book comments on the issue. > My conclusion- You don't need three phases to > generate a rotating magnetic > field. It just happens to be the most efficient and > economical way of doing > it. Jackson's Intro to Electric Circuits defines polyphased currents in the following way. " Less copper is required to supply a given load power at a given voltage with a polyphase system then with a single-phase system." This is based on the usage of a common return line. For two 90 degree phased currents carrying one amp, the return line, designated as neutral in further polyphase schemes, will contain the vector sum of the phase currents, or the sq rt of 2, being 1.4 Amps. By combining the return lines, what would be 2 Amps in a dual single phase system has become 1.4 Amps. Likewise in the 3 phase delivery system both the enter and exit points made by the stator currents carry shared currents, where in that case 1.7 amps will divide into dual 1 amp currents 120 degrees out of phase. "If the load on each phase of a polyphase source is identical, the instantaneous power input of the alternator is constant." On a single phase this does not apply, since there is a point in time when the amperage is zero during the polarity change. To produce the effect of a magnetic field in rotation, a magnetic field must be continually present on one of the coils producing this rotating magnetic field effect. This is done by the amount of off phasing present on the delivery lines, which ideally for the perfect example is 90 degrees. "A single phase system can produce only a magnetic field that increases and decreases in flux density and reverses its direction each 180 degrees but does not rotate." Apparently then magnetic rotation has the prerequisite that a magnetic field that has a collective constant flux density in time appears to rotate through space when expressed through coils arranged in space. It is the effect of two phases acting together magnetically producing the illusion of movement of a constant flux density through space. Thomas further comments; "Also with two currents 180 degrees out of phase, we cannot produce a rotating magnetic field."

In the production of magnetic fields by resonance from the alternator frequency, a most perculiar perplexing problem developed conceptially. A table of 30 coils lined in two rows of 15 was split into groups of 10, where the first two columns of ten coils was attached as two phases to the alternator. These columns of .15 henry were resonated, whereby the peculiarity of loose magnetic coupling showed that while in reactive measurements they exhibited no mutual inductance, at resonance the mutual inductance effects were very evident. The two outputs appeared as 180 phases, not as two phases at 120 degrees as would be suspected. Both the input amperage lines and the internal voltage rise differeneces of the phases showed that a near 180 degree difference was present on two of the phases, making a combined q factor in the 40's. Now then the third coil system as phase 3 was added as a folded column of 5 coils each, also .15 henry, but this system would not conduct a balanced amperage with the other phases, giving about half the value of conduction as the columns in mutual induction lengthwise. Normally the extraction of a third phase current will detract from the currents formerly found on two phases, but in this example the reverse situation occurs. The former phase angle measured near 180 is only slightly reduced by the addition of the third phase, but its interphasal voltage difference has increased. The first measurement of the added voltage difference of phase 3 now shows another 180 phase angle. This should only leave about 20 degrees for the remaining phase angle voltage measurement. However this measurement shows about 60 degrees. More voltage is measured inside the three phases series resonant voltage rises then can be accounted for in time.

In this proposition it seems incredible enough to blindly assume that three magnetic fields in opposition on these columns would in turn produce a more expanded interphasal voltage difference, to the point where it can be made experimentally measureable employing spirals in mutual inductance. In the previous example the voltage rise of phase 1 and 2 were 372 and 387 volts, producing 722 volts beween them. This 95% of the amount that would be present if the angles were 180 in phasing. The third phase has a resonant voltage rise to 188 volts from the 14 volt stator, and the next interphasal voltage measurement shows 372 volts and 188 volts combining to yeild 561 volts, slightly over a perfect 180 phasing! Thus the remaining phase angle should only contain the 5% voltage difference contained in the first phase angle example of a summation of 759 volts being expressed as a 722 volt difference, only a mere 37 volts difference. Yet that measurement shows a 388 volt and 188 volt potential combining to form 387 volts between them, which should at least form a 60 degree phase angle. On the three phase circle then we have 60 and 180 and one measured near 95% of the summed voltage values that would mean a 180 phase angle. The sin-1 of .95 is 1.25 rad vs 1.57 rad for a quadrant circumference making the phase angle deviance (1.25/1.57)*90= 79.6 degrees. Thus we actually have about a 160 degree phase angle, a 180 degree one and a 60 degree one, adding to 400 degrees when it should only add to 360.

Obviously the 30 coil structure needs to be rebuilt with the ten groups all aligned together so that all three are loosely magnetically coupled chains at resonance. It may be rediculous to assume that three 180 phased systems can be built but the idea is there. The requirements of capacity for mutually coupled spirals for each phases use becomes quite large for making such a system, where the interphasal voltage gain made by three 180 phased magnetic fields is compromised by the fact that the q factors of the spirals themselves will have been reduced. I am going to look at some reactance data of these spirals, where my tests showed that mutual induction can double the reactance currents. HDN

> As an aside- Even with only one phase and no added > capacitors (so no > rotating magnetic field at all) a three phase > induction motor will run. But > pretty poorly and the starting torque is zero. > > Motor textbooks explain this by saying that the > single phase pulsating field > is the sum of two rotating fields spinning in > opposite directions. When the > rotor is at rest they cancel giving zero torque. But > set it spinning by hand > and the torques no longer cancel because the slip > frequencies for the two > fields are different. > > Steve C. > > >

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Tesla Research Group; Pioneering the Applications of Interphasal Resonances http://groups.yahoo.com/group/teslafy/

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