VR3 Regulator Problem

This may, or may not, help.

Electric motors, generators & controls engineering - Caterpillar ...
When all else fails, call "the man".

Fuses "burn" for a reason, and the reason is too much current passing through them. If all of them are blowing at the same time then your only option is to call the manufacturer or the place that sold it to you.

Some where you have a combination of faulty/improper grounding and a phase to ground short circuit; a deadly combination to the uninitiated. Do not operate that system until someone who knows what they are doing is leading the effort.

I'll take a WAG that the OP does not have any way to measure the current going through the fuses before they open. A trained eye can sometimes tell by looking at the remains of a glass tube fuse if just over or dramatically over current condition happened that caused them to blow.