GROUND MONITORING AND BREAKER ACTUATION DEVICE

摘要

A ground monitor and circuit breaker actuating apparatus for monitoring the continuity of the ground and pilot conductors in a power distribution system and for deenergizing the power supply system when a true fault in the ground or pilot conductor occurs, including a DC power supply, an impedance bridge which passes a test signal whenever a bridge imbalance occurs in response to a fault logic signal or a fault in the pilot conductor or the ground conductor, an oscillator which generates a test signal for use by the bridge, a fault logic generator which generates a fault logic signal for causing intermittent unbalancing of the bridge and for use by a pulse rate discriminator, a filter which eliminates spurious signals passed by the bridge, a pulse former which converts the filtered signal into a pulsed fault signal, a threshold detector which passes the fault signal if the voltage level of the pulses exceed a predetermined threshold voltage level, a phase detector and a null output detector which compare the phase relationship between the test signal and the fault signal and which indicate when the bridge is in an unbalanced condition, a pulse rate discriminator which compares the timing of the pulses of the fault signal with the pulses of the fault logic signal and develops a control signal commensurate therewith, and a relay which breaks the circuit of the power system in response to the control signal.