I really don't have a lot of information right now other than an event. We had an arcing fault that likely coincided with an operation of the VCB being used as a motor contactor. It escallated into a large arcing fault that did a lot of damage. We have not yet had a chance to take the remains...
I am looking at a Toshiba VCB that was used as a contactor for a 4160-V motor. There was an arcing fault at the contactor. Does anyone have experience with this type of failure? Especially with a Toshiba VCB?
Thanks
The secondary neutral of the 480 Delta to 120/208 Y is solidly grounded and is also connected to the #2 Ground. The operating curves for the 200 Amp fuses are WAY below the thermal damage curve for the #2.
I suppose that we could have a ground loop but that would be a hell-of-a loop to pump...
Grounding the neutral in two places? It seems to me that would be difficult with a Primary delta. There is no neutral. I suppose a poorly grounded neutral on the secondary could allow for a ground potential rise but it would take well over 100 amps to damage the #2 AWG.
A little more...
I am looking at a problem with a cable run on the primary side of a 480 delta - 208/120 transformer. The transformer feeds loads with relatively high harmonic current. The equipment ground wire on the primary side has severed from what looks like overcurrent but it is within NEC specs (#2 AWG...
