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120 volts...but low wattage

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  • #16
    Re: 120 volts...but low wattage

    If things are right I would think the Generator should start the pump, if it is wired for 220.

    we have a 3750 watt unit and would start and run a 10 gallon min submersible at 260 feet under pressure, it would lug down for a few seconds and then come back up to speed, and I think it is a 1 1/2 hp unit motor on the pump, It was not the best, but it would do it.

    NEVER GO BY THE SURGE RATINGS. it is just pie in the sky, a generator is really only as good as it rated wattage is, (I am not saying you are using the surge ratings but there next to meaningless).

    you may need a clamp on amp meter and start to see what things are pulling, and you generator engine may need a tune up as well, It just sounds like to me that the engine is not producing the power it should to keep up with the load, from your descriptions,


    If you have a old plug in clock with a second hand, plug that in and see if the clock seconds are the same as a wrist watch or a battery unit,
    if your engine is not near the correct speed, if can cause problems for both the alternator as well the load trying to be driven.
    (a plug in clock can be a very accurate frequency meter), (the clock should be in the 55 to 65 seconds equaling one min on a small generator, the closer to 60 seconds to a min the better,)
    under light load many run about 62 cycles and under load it should not drop much below 58 cycles, if your much more on ether side of that it can cause your equipment problems and over heating and so on,

    resistant loads like heaters do not care, motors will start to over heat and run at different speeds if the cycles are not correct and electronics may have some real problems,
    Last edited by BHD; 09-28-2009, 05:29 PM.
    Push sticks/blocks Save Fingers
    ~~~~~~~~~~~~~~~~~~~
    "The true measure of a man is how he treats someone who can do him absolutely no good."
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    • #17
      Re: 120 volts...but low wattage

      This is all reminding me of the huge differences in several generator ends (attaches to engine) where a really well engineered and build USA made one such as a Gillette can put out loads of peak starting current/power for a few seconds as long as the engine speed remains close to nominal speed for 60 Hertz which in most cases would be 3600 RPM. Gillette also makes the same generator but setup with an end bell with ball bearing so it looks much like an electric motor. These are normally belt driven units. If you were to oversize the engine so you have far more than enough power and you keep the speed close to 3600 RPM (generator) you can force out quite a bit more than rated power. On the other hand a cheapo import of the same rating (continuous power) has far less iron and copper and may well burn up if run at rated output for long. As for any reserve surge/peak power, you can forget about it.

      What I'm getting at is that with all too many portable and some stationary generators the ratings are pretty worthless. It's how they came up with the ratings that matters.

      Now getting back to the hard starting pump, it may well take up to 10 times the running current to start it up and it may need that for as long as 10 seconds to reach full speed. If there are slightly worn out starting or running capacitors or a check valve not fully opening, then the motor really has it bad.

      What you need is to find a good local electrician with a peak reading clamp-on Ammeter such as a Fluke 336 or 337, but there are others that will serve well. Starting up the pump across utility power, note the peak Ampere draw. Then figure in some power factor and 240 Volts. You may well find that even a 10,000 Watt generator will grunt to start the pump.

      Another issue is to try really hard to keep Voltage drop (from power source to motor) as low as you can within reason. Exactly what are you putting in the path (wire wise) from the pump controller and your generator? How many feet and what gauge power cord? (2) What gauge wire and how many feet of it are there from the controller to the actual pump down in your well?

      If you can somehow connect up a pointer type meter (A good VOM multimeter like a Simpson 260 or Triplett 630 works well for this) set to 0-250 or 0-300 Volts AC so as to measure Voltage right at your generator will answer lots of questions?

      1. Voltage under no load

      2. Voltage with generator powering (2) 1500 Watt heaters

      3. Voltage when generator tries to startup pump. Only let it grunt just long enough to get a good reading and then open the switch. If you don't you can burn up both your generator and the pump motor.

      4. Voltage at controller output when generator is trying to start pump

      5. Using utility line power, measure Voltage at the controller both with the pump stopped and also at startup.

      The bottom line is you want to find a good local electrician with both a peak reading clamp-on AC Ammeter and a good VOM Multimeter of the pointer (not digital readout) type. He/she will know how to setup and run tests for you.


      BHD has a great idea about how to use an electric clock with a second hand to measure frequency (engine speed) and I recommend allowing 5 minutes per test.

      60 Hertz = Watch or good battery clock and electric clock run at the same speed. 5 minutes and 5 minutes

      63 Hertz = Watch says 5 minutes and electric clock says 5 min. 15 sec.

      57 Hertz = Watch says 5 minutes and electric clock says 4 min. 45 sec.

      Your KillAWatt may be able to read frequency so you may want to check the manual. Also some good clamp-on meters can read frequency.
      Last edited by Woussko; 09-28-2009, 11:56 PM.

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      • #18
        Re: 120 volts...but low wattage

        Sorry for such a long post. It's time for me to go back inside The Woussko Hut again.

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        • #19
          Re: 120 volts...but low wattage

          Ok..there you have it. It is completely within reason that my genny just dont have the guts for the start up. At least I know my genny is not toasted. Thanks guys.

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          • #20
            Re: 120 volts...but low wattage

            one could check out the control box and make sure the capacators and the relay is in full working order.

            when one hooks up the generator is it exclusive to the well?
            or is it back feeding the line and possibly feeding other loads as well?

            what size or horse power is the engine is on the generator?
            Push sticks/blocks Save Fingers
            ~~~~~~~~~~~~~~~~~~~
            "The true measure of a man is how he treats someone who can do him absolutely no good."
            attributed to Samuel Johnson
            ~~~~~~~~~~~~~~~~~~~
            PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

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