Protection against accidental contact for two power supply lines connected to a common load

摘要

The circuit detects current in both supply cables via measurement current transducers (3,4) connected via a resistance (5) into evaluation electronics (8) which compare the current with a defined threshold value. If the measured current is less than the defined threshold the supply connection between the supply point (1,2) and the load (10) is cut off. Each supply cable has an isolating switch for interrupting the current flow. There is at least one current measurement transducer in a different phase in the two cables. The evaluation circuit produces a single switch control signal for interrupting all phases.