RE: Three Phase Generation and transformer

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Leigh Copp" <Leigh.Copp@xxxxxxxxxxx>

Jim,

This is a very common arrangement actually. Most modern services that I
have worked with are a Wye, and most isolation transformers are
delta/Wye.

Ground the X0 of your Wye from the generator, and connect the three
phases to your delta primary. Then ground the X0 from your Wye secondary
also. They used to forbid this in the electrical code, (at least the
Canadian one anyway), but it is now the rule. You don't need to ground
your HV primary neutral, but it won't hurt either.

Leigh

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: February 18, 2007 9:19 PM
To: tesla@xxxxxxxxxx
Subject: Three Phase Generation and transformer

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

Does anyone know?

Thanks,
Jim Mora