Single-pole switch

electromechanical

The fault thrower is a means to introduce a phase to earth fault to ensure remote end tripping of a circuit breaker, by assuming that pilot wires are not available for inter-tripping. The remote circuit breaker needs to be operated during equipment faults such as thermal protection or low level fault currents which are not possible to detect by using remote protection. The fault thrower is typically used with transformer feeders make the remote feeder breaker respond to the transformer local fault detecting relays, such as Buchholz protection, local earth fault protection, etc.