Monitoring circuit for switching installations - uses single control wire operating two relays via continuous voltage and higher voltage diode trigger pulse resp.

摘要

The supervision circuit has fault wires signalling faults in switch installation. The fault wires are connected to a control wire through a pulse stage consisting of a resistor in parallel with a capacitor, in series with a diode. The control wire leads to an evaluation unit in which the fault signal switches on two signals by two relays. The first relay is operated by a continuous voltage derived from the fault signal. The second relay is connected to the control wire through a triggering diode whose switching voltage is higher than the continuous voltage. It is operated by a pulse voltage derived from the fault signal, higher than the diode switching voltage.