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Solar Tripping M.C.B.

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Evenin' All,


What would cause a domestic solar panel system to trip off its 16 Amp M.C.B. in the consumer unit if any of the below happens please?


a, Turn off and on consumer unit R.C.D.


b, Turn off and on Dedicated solar system isolator switch.


c, Turn off and on  solar system 16 Amp. M.C.B. in consumer unit.


All happened on an overcast drizzly day.


Thanks,


Z.
  • 0
    Sounds like a similar issue to the B16 MCB tripping when I plugged in one of my 110 volt tool transformers today.


    Andy B.
  • 0

    Sparkingchip:

    Sounds like a similar issue to the B16 MCB tripping when I plugged in one of my 110 volt tool transformers today.


    Andy B.




    Inrush current?


    Z.

  • 0
    That would be my first thought too; lots of older inverters have transformers in, plus the caps. What make/model is it?


  • 0
    First thought is try a C type MCB, Zs permitting.


     Andy B.
  • 0

    Jam:

    That would be my first thought too; lots of older inverters have transformers in, plus the caps. What make/model is it?


     




    Hello Jam,

                          I have no details on the system as I was not there to look at it. Whilst I was there doing something else I noticed the problem. The system seems quite old though. Most solar M.C.B.s are B16 I find. They seem to operate o.k.


    Z.

  • 0
    Or a faulty inverter?


    Does the MCB trip immediately on switch-on or after a delay? (e.g. most inverters have a delay of many tens of seconds after grid power returns before re-connecting themselves).


      - Andy.
  • 0

    AJJewsbury:

    Or a faulty inverter?


    Does the MCB trip immediately on switch-on or after a delay? (e.g. most inverters have a delay of many tens of seconds after grid power returns before re-connecting themselves).


      - Andy.




    Yes on some occasions the M.C.B. trips instantly after turn on of the main R.C.D or turn on of the solar isolator. The tripping off is a bit random. I managed to keep it on after a few tries.


    Z.

  • 0
    If it is inrush it will appear random.

    I once was asked to test the inrush current of a transformer (it was for aircraft use at 400Hz) and the first cycle measured 100 times nominal current if the instant of switching was as the voltage passed zero. If it was switched at voltage max then first cycle was near normal.

    The reason for this is that as the voltage passes zero then, in the steady state, the applied voltage is opposed by a rapidly decaying magnetic field but this is absent at switch on so the only opposition to the first half cycle is the DC resistance of the winding.
  • 0
    Thanks Harry, that seems to be spot on.


    Z.

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