Posted on February 04, 2014 at 05:18Your selective (900V) mosfet is seem too low of voltage rated. Vds = Vin(max) + ( Vout x Turn Ratio) + some extra spike (around 10% of V_reflect) Vds = (400Vac x 1.414) + (16 x Turn Ratio) + ( 16 x Turn Ratio x 0....