R
Robert L. Bitner
Based on some years of experience at a Shipyard with an ungrounded electrical system, I generally found that separate phases of separate equipment in separate areas of the plant would simultaneously blow across ground when their insulation became weakened and ionize sufficiently. Just like lightening exploding under similar circumstances. To add to the problem, the systems utilized circuit breakers and when the equipment did fail as mentioned above, it normally took out a main air breaker in addition to the molded case circuit breakers in each area of the plant. In your case, I wonder what other equipment not directly associated with the MOV fault but indirectly tied to your distribution system might have blown at the same time as I suspect this happened. Bob Bitner