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dmtonyole
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Join Date: Dec 2006
Posts: 77

Rccb Tripping During Supply Exchange

08/15/2012 9:51 AM

Hi

RCCB is tripping whenever there is exchange of power supply from the utility to generator. There is no fault in the circuit, what might be the cause?

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Mtonyole
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silverfox
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#1

Re: RCCB TRIPPING DURING SUPPLY EXCHANGE

08/15/2012 10:09 AM

The RCD will trip if there is an inbalance between what goes out and what comes back. If one of your breakers has a slight delay on the neutral pole when switching you could easily trip the RCD.
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kvsridhar
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#2
In reply to #1

Re: RCCB TRIPPING DURING SUPPLY EXCHANGE

08/15/2012 5:18 PM

Neutral??? An RCD uses a CBCT, so all 3 phases and the neutral will pass through it. The RCD therefore will trip ONLY for an earth leakage. No unbalance in phases or neutral should actuate it.

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pnaban
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#3

Re: Rccb Tripping During Supply Exchange

08/15/2012 11:20 PM

check neutral/earth on both sources.

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LAA_Lucke
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#4

Re: Rccb Tripping During Supply Exchange

08/16/2012 1:58 PM

You might have a neutral wire wounded and making a slight contact with a grounded chassis or frame, somewhere in the circuitry.

If the neutral to ground on the generator is very good an near enough, and the neutral of the generator is being switched On and OFF with the change/Over, then the leak will be a little bit greater than when on the Utility supply ( maybe??).
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silverfox
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#5

Re: Rccb Tripping During Supply Exchange

08/17/2012 3:28 AM

Another thought - when you disconnect the supply from the land supply to the generator are all connections broken. If there is disturbance on the line and lets say a voltage between neutral and earth has been caused this could be seen by the RCD as an imbalance and cause the trip.

Is the RCD there for personnel protection or because you have issues with a high Ze.
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electricalexpert65
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#6

Re: Rccb Tripping During Supply Exchange

08/20/2012 11:52 AM

Possible harmonics, amplified by the greater generator impedance?
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