Abstract
First the welding current and voltage waveform was analysed by the waveform analyser containing a microcomputer. Then the correlation between waveform data and arc stability was im estigated. When welding current is low, the standard deviation of an average current in a short circuit duration and the average interval between short circuits, etc. correlate-well with arc stability. But when the current is increased, these correlations become poor. From the results of multiple regression analysis about waveform factors and arc stability, four factors which correlate well with arc stability were selected. A general index for arc stability which uses four factors was established. In the welding tests under various conditions, this index was shown to be capable of differentiating between stable and unstable arc.
