I can not find a datasheet of any of these bridge rectifiers. I did find information that said MDA 952-5 is 400v 200a but I find it hard to believe this tiny thing is rated 80KW
There is some variability among manuracturers and cross-reference tables. Here are representative numbers. For all cevices, the -5 suffix indicates a 400 V PIV rating.
MDA962 = 10 A continuous, 300 A 1-cycle surge.
MDA952 = 6 A continuous, 125 A single-cycle surge.
MDA90 = 30 A continuous, 300 A single-cycle surge.
the voltage spec is for inverse (i.e. when the diode is not conducting) and the current is the maximum current in the forward direction. with forward conduction, the drop across the diode is only 0.7V, so, for instance the MDA-962 at 10A would only dissipate 7 watts (actually 14 watts, since you have two forward biased diodes at a time in a bridge rectifier.
with forward conduction, the drop across the diode is only 0.7V, so, for instance the MDA-962 at 10A would only dissipate 7 watts (actually 14 watts, since you have two forward biased diodes at a time in a bridge rectifier.