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Back up generator

  1. Jul 9, 2010 #1
    Hi friends,
    Iam from india(230v).Iam no good in Electrical distribution.We have a back up generator in our community of 160kva.We have 90 apartments. From the generator wiring is directly done to few lights points and fan points in the household which would make them function when the normal powersupply fails.But I wanted the supply to be given directly parallel to the normal supply with a current limiter so that we can choose the load as per requirement.
    But the builder says it may not be possible now and he quotes reasons which i dont follow fully and agree...He says there would be problem with gene neutral and normal supply neutral which I cannot agree.I feel all that is required is a automatic changeover switch with a current limiter.
    note :Generator is a 3 phase generator. But only single phase is given to individual apartment.(may be distributed)

    My questions are,
    1.Is my understanding right that it should be easily possible to connect the generator o/p to each apartments main parallelly with a changeover switch and current limiter.

    2.What should be the current limiter rating for above specs.
    3.Would you refer to any particular type auto change over switch.Any brand or make or part no.Because builder is washing off hands that he does not know any.

    Please help me with your suggestion.
  2. jcsd
  3. Jul 9, 2010 #2
    Forgot to mention input from normal power supply is 3 phase 230 v.
  4. Jul 10, 2010 #3
    What you need is a droop setting on the governor of your engine. When you parallel to the grid, you'll need a synchroscope to make sure you're in phase with the grid before closing the breaker connecting the generator output to the grid. Most utilities will adjust the governor of the engine to make sure the engine is running a little higher than the grid (60.1 Hz for a 60 Hz grid in the US). This is done to ensure that the generator picks up load when it is paralleled. If the generator speed is below the grid frequency, you run the risk of motoring the generator.

    I'm not sure what you're thinking with the change over switch and the current limiter. A droop setting on the engine governor will accomplish the current limiting behavior that you're after, as the governor will adjust engine speed to provide the power that you set on the droop control.

    Google droop and diesel generators.
  5. Jul 11, 2010 #4
    I think that the main problem that you will have is overloading the generator 160 KVA gives a little less then 2 KW per household if all the house holds have for instance electric water heaters, freezers etc they could well overload your generator, this is probably the reason that houses were originally supplied with only a few lights and sockets, in the first place.
    I'm not sure what you mean by a current limiter in an industrial setting a current limiter is a device that reduces the spike of current in a fault condition it's not a "valve" that can limit the flow of current into an individual house or flat.
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