Power Semiconductor Current Ratings for Welding Applications

The power handling capability of thyristors and silicon rectifiers have, in the last few years, increased to the power handling application range previously served by the ignitron. The ratings of the power semiconductor, however, are significantly different than ignitron ratings. Power semiconductor ratings are compared with ignitron ratings when applied in welding and other applications having cyclic loads. By careful review of how averaging time is defined for power semiconductors, the ratings of thyristors are presented on the well-known ignitron rating format. This permits direct comparison of the power handling capabilities of the power semiconductor to the ignitron.