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Re: Three Phase Generation and transformer



Original poster: Bert Hickman <bert.hickman@xxxxxxxxxx>

Tesla list wrote:
Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>
Hello All,
I am nearing completion of my 3 phase 20KVA Diesel powered generator. Yup, Portable power! The generator is currently wired 277/480V Wye. I have a 480v delta to wye step down transformer which would then be 208/120 (with neutral). My HV supply wants to see 208v 3 phase and a neutral which in turn supplies 28KVDC. * is it ok to connect the generator 480v wye (sans neutral) to the Delta Primary of the step down transformer?

Driving a Delta load from a Wye source should be OK as long as both are rated at 480 volts phase-to-phase...

* If so, how should the wye generator, delta-wye step down transformer, and wye HV step up transformer be grounded?

Connect the neutral of your generator, the neutral of your step down transformer wye output (and thus the neutral to the LV side of the HV transformer) together and earth the combined connection at a single point via a ground rod. In general, the chassis of the generator and frames/cases of the transformers should also be bonded together and grounded. Specific details covering grounding are covered in National Electric Code (NEC) section 250 - Grounding (section 250-6 deals with portable generators). A copy of the National Electrical Code Handbook would also be useful... your library should have the latest copy.

Does anyone know?
Thanks,
Jim Mora


Good luck and play safely,

Bert
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