Hello, i have strange problem, i have my welder about 3 years, its ac/dc tig , few days ago, when i weld in 160A ac range, tig blown house fuses, fuse was 10A, after third shut down time, when i go to turn on automatic fuse, welder try to starts, light all indicators, and after 1 sec blown fuse again. i was know that something broken inside. i open welder, and after few minutes of searching i sound two shorted igbt, in some kind of power supply board. in total the are 4 igbt, connected to 4 individual wires, going to strange looking transformer. The igbts are IKW50N60T. i bought 2 new for replace, replaced shorted one, and welder work again, i also replace home fuses from 10A to 16A with delay. i use welder for about 1h, and on my mistake when i was finishing weld, i touch tungsten to base metal( where i have connected ground lead) and it tungsten stick for 1s. house fuse blown again, and again when i turn it on, and turn on welder, it again blown fuses, so again it seems like shorted igbt, i open again welder, and again the same 2 igbt that i replace got short. right now i order again new set of IKW50N60T, but why its again blow, any ideas?
its any way to protect igbs with some diode or something? igbt gate is controlled by transformer, and few resistor and diodes.