Breaker and abnormal electrification measurement circuit null for welding machine

摘要

PROBLEM TO BE SOLVED: To provide a circuit breaker for a welding machine, which can be used at the level setting value of an identical current measuring circuit 3 irrespective of whether an electric circuit is composed of a three-phase wire or of a single-phase wire. ;SOLUTION: A circuit breaker for a welding machine is provided with a first half-wave rectifying circuit 2a and a second half-wave rectifying circuit 2b which half-wave-rectify the output signal of a first current detector 1a and the output signal of a second current detector 1b, with an addition circuit 3 which adds their output signals S2a, S2b, with a peak hold circuit 4 which detects a peak value from an addition signal S3 and through which a signal at a level according to a peak value is output for a prescribed time, with a measuring circuit 5 which measures whether a hold signal S4 from the peak hold circuit 4 is at a reference value or higher and whether the signal is continued for a reference time or longer and with a trip circuit 6 which trips a contact 10 according to a measuring signal S5.;COPYRIGHT: (C)1999,JPO