DEVICE FOR MONITORING THE STATE OF AN ELECTRIC SWITCH AND ITS USE IN AN ELECTRIC RELAY

摘要

A device for monitoring the state of a relay comprises an electrical insulation transformer whose secondary winding is connected, through a rectifier, to the output terminals of the relay. The primary winding of the transformer is in series with an oscillator having an impedance greater than that of the primary winding when the relay is closed. A transistor receives a signal from the primary winding and delivers an on-off output signal representing the impedance across the terminals of the relay.