In the picture below, there are three TVS diodes in series (D13, D14, D15). They are placed from drain to -13V reference, which is the reference for the rectifier. The diodes are 1.5KE300A, they have a breakdown voltage of 300V, so if they are in series, the total is about 900V. My questions are:
Wouldn't it be better to put the TVS diode in the output of the rectifier?
Could the number of diodes be reduced? Maybe using more modern diodes? The input line to line voltage can reach 480 VAC.
I didn't design this. I'm just trying to understand it and probably make it more robust.