Device for protecting AC supply against direct current fault current e.g. smooth direct current, has fault current generator coupled to circuit breaker and sensing unit and generating change current dependant on detection of fault current

摘要

The device (2) has an earth-leakage circuit breaker (10) changing fault current. A sensing unit (12) detects direct current (DC) fault current. A fault current generator (13) is coupled to the earth-leakage circuit breaker and the sensing unit and generates change fault current dependant on the detection of the DC fault current. The sensing unit comprises a sum current transformer (14) for detecting the DC fault current. The fault current generator comprises an evaluation logic unit (16) for evaluation of a signal from the sensing unit. An independent claim is also included for a method for protecting an AC supply against DC fault current.