Loading ...
Sorry, an error occurred while loading the content.

Re: Three Phase Motor as Alternator/ Latest Developements

Expand Messages
  • Harvey D Norris
    ... alternator. The ... the direct ... Is this ... whatever the ... Sorry Dave, cant help you much here. Years ago I tried running a 3 phase induction motor
    Message 1 of 7 , Mar 7, 2003
    • 0 Attachment
      --- In teslafy@yahoogroups.com, "David Thomson" <dave@v...> wrote:
      > I have a three phase, 400 Hz motor I'm hoping to use as an
      alternator. The
      > three hot wires appear to be in delta formation. When I measure
      the direct
      > AC voltage between the hot leads I get 2 volts between each pair.
      Is this
      > correct? Am I wrong in thinking there would be 120 volts (or
      whatever the
      > motor rating is for the rpm I'm running?)
      >
      > Dave
      Sorry Dave, cant help you much here. Years ago I tried running a 3
      phase induction motor backwards as a generator, but I did not have
      any success. This was clear back around 1990, and I really didnt
      know much back then. It was shortly afterwards that I first made an
      AC car alternator modification, since that didnt work. I quickly
      burnt that one up by driving it at an ungodly rpm, again back then I
      didnt know that the 7 pole faces would give 7 cycles per rotation,
      and that model melted the stator insulation off when driving it at a
      fast rpm that produced some 833 hz. Lindsays publications of a short
      pamphlet called "Alternator Secrets" notes the following on your
      problem.
      "Induction motors have no physical connection between the the
      stationary winding and the squirrel cage rotor. The electricity
      flowing in the rotor is created by transformer action because the
      magnetic field in the stator winding is revolving at 1800 rpm, while
      the rotor is revolving at 1725 rpm. The 75 rpm difference, (4 to 5 %)
      causes a current to be induced into the rotor.(This is a 60 hz
      example , HDN)
      When used as an alternator, the motor must be driven 4 to 5 %
      faster than the 1800 rpm synchronius speed, (to obtain the 60 hz as a
      motor driven backwards as a generator HDN)
      Some motors will begin generating power as soon as they're
      driven because there's a small amount of residual magnetism remaining
      in the rotor and windings. ( Note: I dispute some of that theory,
      because it does not also acknowledge that this also consists of a
      parametric generator, and we ought not just hypothesize that is is
      working by residual magnetism. The 2 volts you are obtaing is
      probably due to the parametric effect of making a changing inductance
      over time on the motor windings, by rotation of the ferromagnetic
      pieces of the squirrel cage rotor HDN)
      If generation doesnt begin by itself, you'll probably have to
      hit the windings with a pulse of DC current to get it started. A
      switch to a 12 volt battery will probably be adequate, although in
      some cases you may need as much as 60 volts to do the job.

      Lindsays manual also notes the following; Not all motors will work
      properly, ( when reverse driven as a generator, HDN), and we dont
      really know why. Fortunately most do.

      In other news I have made a electrified pepper seed experiment, where
      I will soon post a detailed post about the Rife/ Lakhovksy variation
      used to make that experiment. Hers a posting sent to JLN list as a
      small introduction;

      This might also be relevant;
      Human Body Found To
      Make Its Own Ozone
      http://rense.com/general35/hmn.htm
      Makes one wonder if we are ingesting ozonated
      water, does this help our immune system? I guess some
      Scandinavian countries routinely use ozonation for the
      water supplies, vs the US practice of using chlorine.
      I think I read some time ago those countries did not
      widely employ vaccination programs like the US did in
      the 60's, yet they did not have outbreaks of epidemics
      that were feared to happen without such a vaccination
      program.

      Havent had time to go into detail about how this
      experiment was done, but heres the results of a 7 day
      pepper seed germination experiment. Two tablespoons of
      sweet cherry pepper seeds for each sample were used
      for the experiment, and then the ones that appeared to
      be sprouting were separated after 7 days.
      Electrified samples were given 1/2 hour daily
      exposures to high voltage. The highest voltage for
      the samples was at the North pole of a 3 inch stack of
      SrFe magnets, the arc bar sample was placed
      afterwards in series from magnet windings where an arc
      was derived after a voltage reduction made by a small
      4 inch neon in series.. It been real cold in Ohio
      lately, and pepper seeds need good heat to germinate,
      so actually these are not good results for 7 days for
      the amount of seeds used, which is why I used a large
      quantity of seeds for each sample to begin with, to
      detect percentage wise a difference in germination
      rates: I try to keep the heat down in the house in
      the winter, these seeds were kept in a shelf in the
      furnace room, which doesnt actually stay that hot
      anyways with the thermostat set at 60 degrees.

      http://groups.yahoo.com/group/teslafy/files/MED/Dsc00461.jpg

      Latest developements;
      Today I recieved another sample of ozonated distilled water from the
      Ellis water process, and will soon be making conductivity tests on it.

      Work on the power factor corrected air core transformer has sort of
      digressed into limbo lately. I'm wanting to make a definite
      improvement on the existing process before I spend more time
      documenting it. To do this I tried putting primaries on both sides of
      the secondary. Paradoxically this did not improve the secondary
      performance, and the input amperage to primary did not double,
      although that might be predicted. The primary was constructed as a
      figure 8 Binary resonant Tank circuit, with coils above and below the
      secondary high induction coil. The BRS Tank primary did not behave
      as the larger twenty 14 gauge coil model does, where the midpoint
      path shows a doubling of amperage. Instead the same amperage was
      inputed, but each branch also contained the resonant rise of
      amperage, making for a doubling of previous output in terms of amp
      turns on the primary coils, but not a doubling of input amperage. (
      this is not conclusive, I only measured the midpoint pathway, but
      previous tests have shown what I am indicating here, the midpoint
      amperage is identical to the coil amperage in this instance.) I do
      not know why that in some cases the BRS acts as advertised, and some
      cases this does not occur. It may have to do with the coils of each
      branch necessarily being involved with some sort of mutual
      inductance, although that sounds speculative at best, because these
      14 gauge coils have been shown to have very little mutual inductance
      in comparison to the use of large induction coils. It may also
      involve the requirement of making the coils to be finely tuned, which
      in this case they were not, they were just given C values known to be
      approximately correct. The strategy next will be to reassemble the
      figure 8 primary tank, and then to give each of those coils an
      independent secondary as a high induction coil. Then each of these
      will connected to the same output as before, which is the 20 coil
      figer 8 tank. This would be like putting tow output currents in
      parallel, where hopefully then that output's amperage will also
      double. If this can occur, then we will have the situation of a
      doubling of current output. As the situation stands now the current
      inputed to the primary, is evidenced as the same current output on 20
      coils of the same dimension, which is definitely a good perfomance,
      where we have to start thinking that this resembles overunity by I^2R
      losses, even after accounting for the resonant rise of amperage on
      the primary.

      Sincerely HDN
    • Phil Karn
      AC induction motors *can* be used as generators, but it takes some work. You can t just hook the thing up to a load, turn the shaft and expect it to produce
      Message 2 of 7 , Mar 7, 2003
      • 0 Attachment
        AC induction motors *can* be used as generators, but it takes some work.
        You can't just hook the thing up to a load, turn the shaft and expect it
        to produce electricity.

        The best way is to use a 3-phase DC-to-AC inverter as a motor
        controller. These are commonly used to control the speed of large
        industrial induction motors by varying both the frequency and the
        voltage of the 3-phase AC supplied to the motor.

        Remember how an induction motor works. When 3-phase AC power is applied
        to the stationary field windings, they set up a rotating magnetic field
        within the motor. This rotating field induces a current in the rotor,
        which consists of a shorted transformer turn and no external electrical
        connections. The magnetic field then produced by the induced current in
        the rotor acts on the rotating field to cause the rotor to turn in the
        direction of the rotating field.

        As the rotor speeds up, it approaches the speed of the stator's rotating
        field. This decreases both the frequency and the magnitude of the
        current induced in the rotor, decreasing the generated torque. If the
        motor is unloaded and is completely frictionless, the rotor will turn at
        exactly the same speed as the stator's rotating magnetic field and the
        generated torque will be zero.

        As the load on the motor is increased, the rotor speed will drop below
        the stator field speed, increasing the current induced in the rotor and
        increasing torque to compensate. This difference in speed is called
        "slip". When operated as a motor, the slip is always such that the rotor
        turns more slowly than the stator's magnetic field.

        But if you apply an external torque to the motor, the slip will go the
        other way. Now the rotor turns faster than the stator's rotating
        magnetic field and power flows the other way. The unit has become a
        generator. With the inverter I described earlier, DC power will flow out
        of the inverter towards the source (which is now of course a load.)

        This is exactly how the propulsion system in my GM EV1 electric car does
        regenerative braking. It has a 3-phase AC induction motor driven by a
        3-phase inverter powered by a NiMH battery. Hit the accelerator and the
        car speeds up, with the motor acting as a motor. Let off the accelerator
        and the motor becomes a generator; energy starts to flow back from the
        car into the battery.

        There was an article in Home Power magazine a while ago showing how to
        use an AC induction motor as a generator in a small hydroelectric plant.
        They don't keep their back issues online, though, so you might have to
        ask around or purchase a back copy.

        --Phil
      • David Thomson
        Hi Phil, Bert Hickman sent me a link to an article that describes how to convert a 3 phase motor to an alternator.
        Message 3 of 7 , Mar 7, 2003
        • 0 Attachment
          Hi Phil,

          Bert Hickman sent me a link to an article that describes how to convert a 3
          phase motor to an alternator.
          http://www.microhydropower.com/staffpubs/staff4.htm

          Thanks for your explanation of how three phase works. Harvey's explanation
          also helped me out. I'm getting a clearer picture of how to deal with this.
          I think I'll try the DC across a winding technique first. Then if that
          doesn't work, I'll see if I can figure out how to put the right capacitance
          across the windings to generate the rotating magnetic field. I'm glad, at
          least, to know that it is a technical problem and not my 400 Hz motor.

          I tried to put a 10A variac on the drive motor and kept blowing the fuses.
          Apparently the 1/3 hp single phase takes quite a bit of amperage to get
          started. I was hoping that a variable speed on the 3 phase motor might help
          nudge the rotating magnetic field into operation.

          Dave

          -----Original Message-----
          From: Phil Karn [mailto:yahoo1@...]
          Sent: Friday, March 07, 2003 8:56 PM
          To: teslafy@yahoogroups.com
          Subject: Re: [teslafy] Re: Three Phase Motor as Alternator/ Latest
          Developements


          AC induction motors *can* be used as generators, but it takes some work.
          You can't just hook the thing up to a load, turn the shaft and expect it
          to produce electricity.

          The best way is to use a 3-phase DC-to-AC inverter as a motor
          controller. These are commonly used to control the speed of large
          industrial induction motors by varying both the frequency and the
          voltage of the 3-phase AC supplied to the motor.

          Remember how an induction motor works. When 3-phase AC power is applied
          to the stationary field windings, they set up a rotating magnetic field
          within the motor. This rotating field induces a current in the rotor,
          which consists of a shorted transformer turn and no external electrical
          connections. The magnetic field then produced by the induced current in
          the rotor acts on the rotating field to cause the rotor to turn in the
          direction of the rotating field.

          As the rotor speeds up, it approaches the speed of the stator's rotating
          field. This decreases both the frequency and the magnitude of the
          current induced in the rotor, decreasing the generated torque. If the
          motor is unloaded and is completely frictionless, the rotor will turn at
          exactly the same speed as the stator's rotating magnetic field and the
          generated torque will be zero.

          As the load on the motor is increased, the rotor speed will drop below
          the stator field speed, increasing the current induced in the rotor and
          increasing torque to compensate. This difference in speed is called
          "slip". When operated as a motor, the slip is always such that the rotor
          turns more slowly than the stator's magnetic field.

          But if you apply an external torque to the motor, the slip will go the
          other way. Now the rotor turns faster than the stator's rotating
          magnetic field and power flows the other way. The unit has become a
          generator. With the inverter I described earlier, DC power will flow out
          of the inverter towards the source (which is now of course a load.)

          This is exactly how the propulsion system in my GM EV1 electric car does
          regenerative braking. It has a 3-phase AC induction motor driven by a
          3-phase inverter powered by a NiMH battery. Hit the accelerator and the
          car speeds up, with the motor acting as a motor. Let off the accelerator
          and the motor becomes a generator; energy starts to flow back from the
          car into the battery.

          There was an article in Home Power magazine a while ago showing how to
          use an AC induction motor as a generator in a small hydroelectric plant.
          They don't keep their back issues online, though, so you might have to
          ask around or purchase a back copy.

          --Phil


          To unsubscribe from this group, send an email to:
          teslafy-unsubscribe@yahoogroups.com



          Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
        • David Thomson
          Hi Phil, I have tried connecting a 12V 150ma power supply to one leg of the windings and it increased the three phase voltage by a half volt. Before I try a
          Message 4 of 7 , Mar 13, 2003
          • 0 Attachment
            Hi Phil,

            I have tried connecting a 12V 150ma power supply to one leg of the windings
            and it increased the three phase voltage by a half volt. Before I try a
            heavier amperage or higher voltage on the windings I want to try the
            capacitor route.

            I have measured the inductance of one leg of the winding to be 8.08mH. I
            figure a 19uF capacitor would give me close to the 400Hz the motor runs at.
            I didn't have a 19uF capacitor, but I do have a 15uF motor starting
            capacitor. This would resonate at about 457Hz. When I connected the
            capacitor between on pair of windings, the voltage actually dropped. In
            fact, the voltage between the capacitor terminals was zero.

            Do I need a capacitor between each pair of wires to get the rotating
            magnetic field working?

            Dave

            -----Original Message-----
            From: Phil Karn [mailto:yahoo1@...]
            Sent: Friday, March 07, 2003 8:56 PM
            To: teslafy@yahoogroups.com
            Subject: Re: [teslafy] Re: Three Phase Motor as Alternator/ Latest
            Developements


            AC induction motors *can* be used as generators, but it takes some work.
            You can't just hook the thing up to a load, turn the shaft and expect it
            to produce electricity.

            The best way is to use a 3-phase DC-to-AC inverter as a motor
            controller. These are commonly used to control the speed of large
            industrial induction motors by varying both the frequency and the
            voltage of the 3-phase AC supplied to the motor.

            Remember how an induction motor works. When 3-phase AC power is applied
            to the stationary field windings, they set up a rotating magnetic field
            within the motor. This rotating field induces a current in the rotor,
            which consists of a shorted transformer turn and no external electrical
            connections. The magnetic field then produced by the induced current in
            the rotor acts on the rotating field to cause the rotor to turn in the
            direction of the rotating field.

            As the rotor speeds up, it approaches the speed of the stator's rotating
            field. This decreases both the frequency and the magnitude of the
            current induced in the rotor, decreasing the generated torque. If the
            motor is unloaded and is completely frictionless, the rotor will turn at
            exactly the same speed as the stator's rotating magnetic field and the
            generated torque will be zero.

            As the load on the motor is increased, the rotor speed will drop below
            the stator field speed, increasing the current induced in the rotor and
            increasing torque to compensate. This difference in speed is called
            "slip". When operated as a motor, the slip is always such that the rotor
            turns more slowly than the stator's magnetic field.

            But if you apply an external torque to the motor, the slip will go the
            other way. Now the rotor turns faster than the stator's rotating
            magnetic field and power flows the other way. The unit has become a
            generator. With the inverter I described earlier, DC power will flow out
            of the inverter towards the source (which is now of course a load.)

            This is exactly how the propulsion system in my GM EV1 electric car does
            regenerative braking. It has a 3-phase AC induction motor driven by a
            3-phase inverter powered by a NiMH battery. Hit the accelerator and the
            car speeds up, with the motor acting as a motor. Let off the accelerator
            and the motor becomes a generator; energy starts to flow back from the
            car into the battery.

            There was an article in Home Power magazine a while ago showing how to
            use an AC induction motor as a generator in a small hydroelectric plant.
            They don't keep their back issues online, though, so you might have to
            ask around or purchase a back copy.

            --Phil


            To unsubscribe from this group, send an email to:
            teslafy-unsubscribe@yahoogroups.com



            Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
          Your message has been successfully submitted and would be delivered to recipients shortly.