Transmission line fault detector - uses pulse echo to determine if fault is persistent before reclosing circuit after operation of circuit breaker

摘要

The circuit comprises an impulse transmitter and receiver connected to the line. When the circuit breaker opens on a fault a pulse is applied to the line and at the same time to a monostable switch. The echo from the line is detected, amplified and fed to a comparator together with the monostable output pulse. THe timing of the monostable pulse is such that coincidence of pulses only occurs if the echo comes from the line end. - With coincidence the circuit breaker is allowed to reclose. - If there is a time discrepancy between pulses the comparator gives an output which is used to lock out the circuit breaker reclosing circuits.