Answer Posted / pillay
ELCB is actually voltage operated ie the leaked voltage difference between the faulty equipment's earth body and the earth electrode in the ground.If it exceeds about 40 volts it would trigger the ELCB to trip.If the cable to the earth electrode in the ground is broken or earth electrode is of very high resistance the ELCB will not trip even if there is a big voltage leak.So this is no good.
RCCB is actually seeing the difference in the current flowing in and out of the circuit.If the current that flows into a circuit and comes out is the same than no leak had taken place.If there is a leakage than the current that flows out of the circuit will be less.That means some current had flowed out to the earth or some where,than there is a fault the sensing circuit will detect the difference and trigger the RCCB to trip.RCCBs are rated by the sensivity of the leakage current normally by mAmps. If it is rated as 60 AMPS / 30 milliamps that means it can be used for a circuit of up to 60 Amps but if there is a leakage of 30 milliamps and above it will cause the sensing circuit to trigger the trip.Even if the earth electrode is open it will trip so long there is a flow of current away from the circuit maybe while electricuting somebody.
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