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Anonymous Poster #1

Line to Neutral Fault on TN-S System

01/22/2024 7:05 AM

Does the RCD trip for line to neutral fault on TN-S system? (or)

Does it trip only for line to earth fault on TN-S system?

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#1

Re: Line to Neutral Fault on TN-S System

01/22/2024 7:40 AM

No: a live to neutral fault just looks like a load.

Of course, if the fault load is high other safety devices should react.

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#2

Re: Line to Neutral Fault on TN-S System

01/22/2024 11:10 AM

A1) An <...RCD...> won't; see GA #1⇑. A residual current breaker overload [RCBO] will, however, on the overcurrent function and not the earth current function.

A2) Both <...RCD...> and RCBO will also trip on neutral-to-earth fault.

<...TN-S...>

The earthing arrangement deployed is irrelevant in this discussion.

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#3

Re: Line to Neutral Fault on TN-S System

01/23/2024 2:00 AM

RCD will not trip for Line-to-Neutral fault as the device takes in the neutral current (along with line current) for summation.

Earth involvement in fault is necessary for RCD to trip.

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#4

Re: Line to Neutral Fault on TN-S System

01/23/2024 8:36 AM

On a TN-S system generally any "Fault" with respect to the ground as the safety reference point of the earthing mechanisms should trip any of the protective circuit devices incorporated in the system...

Faults like any electrical safety related earth referenced fault that can be due to like a high leakage current, an abnormally drawn current overload or lightning induced surge current, etc..

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