What is pilot wire protection for a transmission line?

Question

incorporated along with main distance protection, over current protection, breaker failure protection etc

Answer 1

A pilot wire protection scheme is used when distance protection cannot be implemented.

Sometimes, the required protection scheme is so complicated that conventional distance or over current relays cannot discriminate all possible fault conditions to trip the appropriate  breaker(s) .

In those cases, it will be necessary to run a pilot wire to pickup fault conditions at a remote location. A pilot wire can be soft or hardwired, depending on distance.

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