Re: Three Phase Generation and transformer

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: David Dean <deano@xxxxxxxxxxxxxxxx>

On Sunday 18 February 2007 20:18, you 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?
Yes.   Not O.K. to use the neutral (Y-Y) with single core- load imbalance
causes circulating neutral current.
>     * If so, how should the wye generator, delta-wye step down
> transformer, and wye HV step up transformer be grounded?
>
As long as none of the transformers or the generator are bonded ground to
neutral you can ground them all to a common point. It should not be an issue
on the transformers (ohmmeter should read open between neutral terminal and
case) but the generator may or may not have a bonding jumper. If it does,
just take it off.
> Does anyone know?
>
> Thanks,
> Jim Mora
Good luck with your project.

later
deano