Protective switching device for a low-voltage circuit for identifying series arcing faults

摘要

A protective switching device for a low voltage circuit, in particular for identifying series arcing faults, includes a measurement resistor BM for measuring current in a line L1 and a measurement circuit ASICA connected to the measurement resistor via two measurement connections MA, ME and a wire connecting line DVL. The measurement circuit is supplied by a power supply NT and the wire-like connecting line DVL is connected to an output of the power supply via a pull-up resistor PR, such that a fracture in the connecting line can be detected if the voltage at the input MA of the measurement circuit exceeds a threshold. A voltage limiter with a pair of opposed diodes D1, D2 may be included between terminals MA, ME. The pull-up resistor has much larger resistance, at least 1000 times, than the measurement resistor. A break in wire DVL may be indicated by optical, electrical or acoustic signalling or by activating the switch UE to interrupt the low voltage circuit.