I have a 3 phase, 4-wire, 120/240 volt delta service to a machine shop. I have recently had some 3 phase equipemnt damaged: an inverter, transformer, and 2 three phase surge protectors damaged from high voltage. There was no damage to any single phase equipment. I suspect an arcing ground...
A zig-zag grounding bank is typically used to provide a source of fault current so a phase to ground fault on a delta system can be detected and interrupted. The bank is sized based on the neutral current and the phase to ground voltage multiplied by a constant "K" which is...
You didn't mention your application so neither of these may be useful. The old type plug fuses that screw into a fuse holder indicate they're blown (max rating is usually 30 amps or less). Bussman makes an R-rated fuse that has a small pin in the end which is pushed outward...
Try ANSI/IEEE C57.105-1978 or later. Section 7, page 22 has a good discussion of Ferroresonance. Best of all, Section 9.2, page 32 has a bibliography with 27 references on Ferroresonance. Item [8], "Abnormal Voltage Conditions Produced by Open conductors on...