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Swimming pool 3 phase motor trips occasionally on earth leakage RCD

CliveS
We have a new 4 kW 3 phase pump motor at the local pool which has a new variable speed drive unit attached and occasionally it trips out on the RCD which I assume is 30mAmp .  The connections are star inside the motor but not earthed which should have stopped it tripping.

We are not sure what to do, we could run the motor flat out and delta connect the windings possibly or some suggest disconnecting the RCD as the circuit is completely separate from normal wiring.  Would this option contravene any of our regs?
  • 0
    CliveS:

    Have found an advert for a type A 300mA RCD Siemens 5SV3644-6 which should not trip.  However, calling it a type A when a type B trips at around 100mA seems a little misleading.  Surely, it would be a type C. 


    I might not have understood what you meant, but RCD "types" are nothing to do with their residual ratings.


    AC types work only with pure AC residual currents (and may fail to trip when they should when the residual current is d.c. or pulsating)

    A types work with AC or pulsating residual currents (but may fail to trip when they should when the residual current is pure d.c.)

    B types work with AC, pulsating or pure DC residual currents.


    There are a few other types that consider higher frequencies too (F) and/or trip when the DC leakage is above a 6mA threshold (EV) (to protect upstream A types).


    As far as I know there is no "C" type for RCDs


    Some RCBOs may be sold a C types - but that's referring to the MCB side (B/C/D type), not the RCD part.


      - Andy.


  • 0
    Thanks Andy,  I am having difficulty finding who makes type B so thought that the Siemens could be suitable.

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