208 wye / 4160 delta step-up transformer

[PP26]

The main purpose of stepping up the voltage is due to voltage drop issues. The feeder run is approximately 6000 feet.

On the distribution location, the voltage will be stepped down again to 208V. Most of the loads are only lighting and receptacles.

Do I need to provide ground with the 4160V secondary delta to the transformer enclosure (through corner grounding) ? Or I can run my secondary as ungrounded system up to the downstream 4160V/208V step down transformer ?

 

[petersonra]

I suspect it is a design decision.

 

[infinity]

On our last project we ran he 4160 Delta as an ungrounded system.

 

[PP26]

Thanks for the response. I appreciate it.

 

[petersonra]

On our last project we ran he 4160 Delta as an ungrounded system.

Would that require a ground detect circuit?

 

[infinity]

Would that require a ground detect circuit?

For that voltage I don't think so (we didn't have any). I believe the ground fault detection requirement is for up to 1000 volts.

 

[electrofelon]

On our last project we ran he 4160 Delta as an ungrounded system.

I always wondered what the advantage of that over running it as an MGN would be? CN cables are by far the most cost effective anyway. I guess ungrounded you could run it inside - IIRC the MGN provision is for outdoor transformers only.

 

[infinity]

I always wondered what the advantage of that over running it as an MGN would be? CN cables are by far the most cost effective anyway. I guess ungrounded you could run it inside - IIRC the MGN provision is for outdoor transformers only.

Actually in our installation the prints called for a 208 ▲/4160 Wye but the transformers that they delivered were 208 Wye/4160▲ so no grounded secondary conductor.

 

[electrofelon]

It does seem odd

Actually in our installation the prints called for a 208 ▲/4160 Wye but the transformers that they delivered were 208 Wye/4160▲ so no grounded secondary conductor.

So we can run ungrounded MV all over and no one cares? Seems kinda odd.

 

[infinity]

It does seem odd
So we can run ungrounded MV all over and no one cares? Seems kinda odd.

I thought so though too but is there any code requirement for a grounded secondary or ground detectors?

 

[electrofelon]

I thought so though too but is there any code requirement for a grounded secondary or ground detectors?

No I just double checked part X and I don't believe there is. Everything still needs to be bonded together and to Earth, but no system grounding or detectors required.