GFPE on optional standby

[derf48]

I need some help, will this work?
2000 amp service, 480Y/277 3phase 4 wire, brought to a 2000 amp GFPE main. Properly grounded at that point, and then a 2000 amp feeder 3 wire only (with equipment ground) run to a transfer switch and then to a distribution panel which serves 3phase loads only. Some of these loads are ups systems, and they will work with or without a neutral run to them.
The generator that feeds the other side of the transfer switch is located 300' outside of the building, is a 1500kva 480Y/277 3phase 4wire system. It has a 2000 amp GFPE breaker installed at its location and then is run into the building as a 3 wire only (with equipment ground)to a disconnect and then to the transfer switch.
Question: will this work using a 3 pole transfer switch? why or why not? The transfer switch supplies optioal standby load only. Will an ups system have a nuisance trip when the transfer switch ? Thank you!

 

[charlie b]

Re: GFPE on optional standby

This seems the ideal setup for a 3-pole transfer switch. Normally, I like to use a 4-pole ATS, when there is a neutral involved. But you don't have a neutral, and don't need one.

The UPS should be able to ride out the transfer of power from the utility to the generator. The users downstream of the UPS should not even notice anything happening to their equipment. They might see the lights go out and on again, but the equipment fed by the UPS should be fine.

I have one possible issue with the generator breaker. At 480 volts, a 1,500 KVA generator has a rated current of 1805 amps. You are proposing to use a 2000 amp breaker. This will not protect the generator from overload. I do not know generators well enough to say if this is acceptable. Any others wish to comment?