315KW Powerflex Variable Frequency Drive

Generally when an IGBT fails, it was just the weakest link and once the first one fails, the drive shuts down, so you have no idea how much stress the rest of them received. But think of this: unless there was a dead short to ground on the output, which should be very obvious, any short circuit current going through one transistor MUST by definition be flowing through at LEAST one other in order to have a complete path. You will not have the ability to discern the damage cause to the other transistor(s) in the field. In addition, if it was the circuit breaker that had to clear the fault, that means the VFD was not able to turn itself off fast enough to protect itself, which then means everything in the power structure was subjected to that fault current; the capacitors, the SCRs on the front end, the firing circuit interfaces, etc. etc.

Send it in, but make sure you insist on an RCFA (Root Cause Failure Analysis) report. If you don't ask for it, you will not get it. Also, given the circumstances here, it's highly likely that you do NOT have a load reactor on this drive. A load reactors best purpose is that by adding inductance to the load circuit, any conductor failure will have the rise time of the fault current slowed down to where the VFD can act fast enough to protect itself. Without that, it's a gambol, and this time, you lost.