| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a consumable electrode type AC arc welding power unit that is simply structured and capable of greatly reducing generation of spatters. Ž<P>SOLUTION: The power unit includes an output control circuit 30 that independently controls four switching elements Ep1, Ep2, En1, En2 and a short circuit detection circuit 36 that detects a short-circuited state or an arcing state existing between a welding wire 12 and a base material 13. The output control circuit 30, when the welding wire 12 and the base material 13 are short-circuited, turns off a first pair of switching elements presently turned-on, for a predetermined period T0. Subsequently, one of the turned-off first pair of switching elements is turned on and, while an electric current flowing on a welding load lowers to a predetermined current value Ias, an energy stored in a reactor 26 is released. Then, when the current flowing on the welding load lowers to the predetermined current value Ias, the other of the turned-off first pair of switching elements is turned on, and the current flowing on the welding load is maintained at the current value Ias for a predetermined period T2, and thereafter the current is returned to the predetermined output current value. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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