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Re: [microhydro] Re: POWER FACTOR CORRECTION FOR SINGLE PHASE MOTORS

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  • ericnoharet@netcourrier.com
    Hello, You are right Bob Some old inverters need capacitor for factor correction on the output and most of modern inverters don t need and may be damage by
    Message 1 of 20 , Feb 1, 2008
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      Hello,

      You are right Bob

      Some old inverters need capacitor for factor correction on the output
      and most of modern inverters don't need and may be damage by capacitors

      In these modern inverters, the "calculator" output circuit correct the
      power factor himself.
      (not realy the power factor but it's not interristing here to go
      in complicated details of hight frequecy systems)

      In some case, you need capacitors on the input off the inverter (in
      motor use as generator) because the "peak consumption" of the inverter
      cause loose of self exiting in the generator.
      For that you can use higt frequency capacitors in parallel of
      the classic capacitor.
      Need a good oscilloscope to solve this type of problem.

      Regards

      Eric
      Ardeche
      FRANCE
    • nando
      PFC of motors can be done on motors that operate at the GRID sine Wave (Pure Sine Wave ) and not MSW ( Modified Sine Wave) and with some practicability with (
      Message 2 of 20 , Feb 1, 2008
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        PFC of motors can be done on motors that operate at the GRID sine Wave (Pure Sine Wave ) and not MSW ( Modified Sine Wave) and with some practicability with ( ASW =Almost Sine wave which is a pure sine wave that may or not may have a flat to in the wave form -- not very common but starting to become common with some Asiatic Inventers).

        There is an article :
        ELECTRIC MOTOR EFFICIENCY MODIFICATIONS FOR SINGLE PHASE FRACTIONAL HORSEPOWER ALTERNATING CURRENT INDUCTION MOTORS

        NWC TM 4552

        By R.A. Weinhardt and F.T. Rogers, July 1981 Naval Weapons Center.

        A Running type capacitor is placed in parallel with the starting centrifugal switch that when opened places the PFC capacitor in series with the starting capacitor, therefore this PFC capacitor is placed in series with the motor starting winding.

        For motors wit more than one speed, one may place the PFC capacitor in the higher speed and not in the lower speeds, unless you complicate the circuitry for each speed that may become quite expensive, higher than the motor cost.

        Empirical work may be easier to find the right capacitor and to attain the best necessary value for each type of motor that may differ from different manufacturers with the same HP value.

        Nando

        ----- Original Message -----
        From: Rural World Resources
        To: microhydro@yahoogroups.com
        Sent: Wednesday, January 30, 2008 10:36 AM
        Subject: [microhydro] POWER FACTOR CORRECTION FOR SINGLE PHASE MOTORS


        HI ALL,
        I WONDER IF ANYONE KNOWS HOW THE POWER FACTOR OF A SINGLE PHASE INDUCTION MOTOR LIKE THOSE IN AIR CONDITIONERS AND REFRIGERATORS MAY BE INCREASED.
        CAN CAPACITORS BE USED AND HOW CAN THEIR VALUES BE CALCULATED?
        CAN SOMEONE HELP WITH INFORMATION?
        THANKS AND REGARDS

        MATT FOMBONG

        ---------------------------------
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      • Rural World Resources
        I am thankful to all, and especially to Nando, who have given advise and suggestion on this topic. I think my question has been answered so far.
        Message 3 of 20 , Feb 1, 2008
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          I am thankful to all, and especially to Nando, who have given advise and suggestion on this topic.

          I think my question has been answered so far.

          ericnoharet@... wrote: Hello,

          You are right Bob

          Some old inverters need capacitor for factor correction on the output
          and most of modern inverters don't need and may be damage by capacitors

          In these modern inverters, the "calculator" output circuit correct the
          power factor himself.
          (not realy the power factor but it's not interristing here to go
          in complicated details of hight frequecy systems)

          In some case, you need capacitors on the input off the inverter (in
          motor use as generator) because the "peak consumption" of the inverter
          cause loose of self exiting in the generator.
          For that you can use higt frequency capacitors in parallel of
          the classic capacitor.
          Need a good oscilloscope to solve this type of problem.

          Regards

          Eric
          Ardeche
          FRANCE






          Eng. Dr. FOMBONG Matt FRU, Executive Director,
          Rural World Resources International
          P O Box 522, Mankon,Bamenda
          North West Province,
          Tel: 00237 99306711/99301407
          CAMEROON



          ref/zgc/002

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        • Rural World Resources
          Greetings to ALL, We are about to start up on building an off-grid, community owned site in Cameroon with the following criteria: gross head: 190m minimum
          Message 4 of 20 , Feb 2, 2008
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            Greetings to ALL,

            We are about to start up on building an off-grid, community owned site in Cameroon with the following criteria:

            gross head: 190m
            minimum flow: 20 l/s
            maximum flow; 3000 l/s
            Penstock pipe length: 500m
            Channel Length: 455m

            Our intention is to use 3 Pelton turbines of

            50 KW
            100 KW
            200KW
            We will be grateful for some advise, especially regarding equipment in kit form.

            Thanks


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