3 phase Residual current devices. 1

[badboyuk]

3 phase Residual current devices.
Can someone explain how an unbalanced 3phase supply can affect the operation of an 3ph RCD when the system has its own earth leakage caused by computer equipment

 

[ruggedscot]

Hmmm, unbalanced three phases refers to the unbalance across the phases, with an RCD monitoring this it will not trip as the unbalance is on the wiring and not due to an earth fault. If you summed up the currents they would cancel out and thus you would not have a leakage issue.

However you talk about earth leakage through computer equipment - this is different and has no relation to the unbalanced LOAD but is a current UNBALANCE. Thus you need to be specific with this one.

An RCD tends to trip only if you have an UNBALANCED current not an UNBALANCED load.

Rugged