Monitoring circuit for switch status in electrical power circuit - has switch coupled to additional AC source and circuit elements forming resonance circuit

摘要

An electrical switch (S) controls the connection of a load (L) to a DC supply (G). When closed the current flows through the primary winding of a transformer (U). An AC voltage supply (W), coupling capacitors (C1, C3), a resistor (R) and a current limiting resistor (Rb) are also coupled to the transformer. Together they form a switch status monitoring circuit (US). The AC signal is superimposed on the DC and causes an induced AC component to be transmitted by the transformer. This signal produced by the resonance circuit indicates the switch status. The circuit may be adapted for use with two series switches. ADVANTAGE - Allows switch to be monitored independently of mechanical construction and characteristic.