I have a question on how this system might be bonded so it trips an overcurrent device in case of a ground fault. The system is a 480v, 3 phase delta to 208v y.
... If 480 is brought to the building and has no neutral and is only operating some hvac equipment, How is it typically bonded so that if there is ever a ground fault it provides a low resistance path to trip the overcurrent device.
Assumption:
Op is concerned with tripping the transformer primary feeder in the event of a ground fault in the feeder conductors or a ground fault the xfm primary winding
Jake -
First you must know the type of 480V system supplying the feeder. Yes I understand the xfm primary is delta and the primary feeder is 3W, 480V 3ph. That does not adequately describe the feeder system.
Probable systems (in order of likely hood):
480Y solidly grounded
480Y impedance grounded
480D corner grounded
480D corner grounded
480D, midpoint grounded (highly unlikely - but possible, right up there with getting hit by a meteor)
Second:
Is there a EGC in with the feeder conductors?
Is the feeder conduit metalic and continuous?
Is there a ground grid, or other low impedance connection between buildings?
Know these two and you will have the answer.
ice