Signalling relay monitoring supply voltage - comprises bistable relays controlled by drive element operated by current transformer

摘要

The voltage (U) to be detected is applied, via a series resistor, to a current transformer (4) controlling a relay drive element (13) whose output controls, via a capacitor, at least one voltage signalling bistable relay (15,27) with voltage isolated relay contacts (22-24,34-36). The transformer output is connected to a storage capaciator (7) with a parallel discharge resistor (9) and to a light emitting diode (6). USE/ADVANTAGE - Monitoring overhead voltage of d.c. railway supply. Relay can be subjected to high test voltages and enables loss-free contact making at voltage to be detected.