| 摘要 |
PROBLEM TO BE SOLVED: To solve failures of such short circuit as is judged though a regular operation is being performed and making a current increase when a welding rod approaches a base material at the time of the regular operation and a voltage between terminals becomes a set value or below, and failures that an arc becomes unstable, sometimes the penetration of the base material becomes much and a hole is made in the base material, etc. SOLUTION: In an arc welding machine equipping with a rectifier 3 controlling an output current by rectifying an output from an AC power supply, a current detector 14 detecting the output current of the rectifier, a setting instrument 15 setting a welding current, a constant current controlling circuit 10 making the welding current become a set current by comparing a detected value from the above current detector with a set value from the above setting instrument and a function for adding an additional current to the welding current when short-circuiting, by providing a means counting a time from the start of a short circuit and when the counted time has passed away by a set time, judging it as the short circuit, and when a time from the judgement to be the short circuit exceeds a short circuit limit time, a short circuit current is cut off.
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