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Choice of a generator set for a drilling pump

  1. Jun 17, 2017 #1
    Hello everyone,
    I am faced with a problem where I have to power a 30kw drilling pump, with a generator of 45kw (model Gesan), but it does not work. At start-up the current reaches the peak of 190 A and descends gradually, for information the start-up of the pump of the drilling is done by a starter Altistart 22 of Schneider with an acceleration set to 15 seconds, and the generator sets overcurrent fault and stop.
    I heard that for this kind of application the generator must have a power of at least 3 times the pump.
    At the moment I am doing tests by acting on the parameters of the starter: acceleration and limitation of current.
    Thanks in advance for any help.
  2. jcsd
  3. Jun 17, 2017 #2
    The inrush current for starting a motor can reach as much as 7 times the running current. Most gensets can stand a very brief overload, but it sounds like your situatation involves a much longer inrush period. I suspect you have two choices: (1) get a bigger genset, or (2) get a different pump motor with more acceptable starting characteristics. Not always a happy choice, but that's life!
  4. Jun 17, 2017 #3


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    You don't mention the voltage but is that France in your profile picture? In which case..

    Quick and dirty calculation for the peak power gives 190 * 230 = 43.7 kW

    My guess is the peak current might even be a bit more than 190A? What's the overcurrent trip set to on the generator?

    Are the cables between generator and pump correctly sized? If there is any voltage loss in the cables then the current drawn might be higher. For example if the pump load remains constant as the voltage reduces then the current increases. For example 43.7kW at 210V needs 208A.
  5. Jun 17, 2017 #4


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    Fit an unloading valve to the pump .
  6. Jun 17, 2017 #5
    Thank you for your answers,
    I solved, as even the problem by setting the boot ramp to 03 sec, I guess the generator does not see such a short startup overcurrent.
    Just before finishing, I have long believed that by increasing the acceleration ramp (either in the dimmer or in the starter) the current is lowered, except in my present case I notice that the current Of startup persisted during the acceleration phase (which was before 15 sec) and my genset fails after 5 sec.
    And by looking at the startup curve of an asynchronous motor, I notice that what happens is very logical. And the lengthening of the starting time of an engine serves much more in applications with mechanical loads which present a great deal of inertia. And in my case it was useless to delay the start too much.
    A +
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