Re: 3 phase transformer connections?

On Apr 14, 7:40 pm, MadDog...@xxxxxxxxx wrote:
On Apr 13, 7:29 pm, Mark Rand <r...@xxxxxxxxxxxxxxxxx> wrote:





On Fri, 13 Apr 2007 16:05:31 -0700, Grant Erwin <g...@xxxxxxxxxxxxxxxxxx>
wrote:

Today I dragged home a 27 kVA 3-phase dry-type
transformer. It's old but I'm hoping still
serviceable. Inside were 3 very dirty, fragile
and waterstained pages stapled together which
were the original build document from GS Hevi-Duty back in 1981. The wiring
diagram is shown:
www.tinyisland.com/images/temp/GSHevi-p3.pdf

It looks like this unit could be rewired for
wye or delta for several voltages. I have a 230V
RPC set up and running. Can someone give me a
recommendation as to how exactly to wire this
transformer? I want to power a 460V machine
with it.

Thanks!

Grant Erwin

Use the "secondary" as the primary, connected to the phase converter (X2
joined to X3; X4 joined to X5; X6 joined to X1 per the picture)

Use the "primary" as the secondary connected to the load on the 468V setting
(or the 456V setting if measuring the output shows the first to be a little
too high) this would be:-
tap 4 on the first winding connected to tap 2 on the second winding;
tap 4 on the second winding connected to tap 2 on the third winding;
tap 4 on the third winding connected to tap 2 on the first winding.

So both sets would be wired delta, but would give you the voltage that you
require. You may want to ground the output by using either three wye connected
chokes, or three 270V stacks of light bulbs, just to stop the output wandering
too far away from ground.

HTH

Mark Rand
RTFM

Sounds like the proper wiring, but I'd offer a caution.
That transformer is a dry type, 26 years old, and the instructions on
the
inside were wet at some time.

I'd do some testing before hooking the thing up.
Look for leakage line to cores, case, ( ground), at a minimum.
If you don't have a megger, use line voltage. - (Careful, the
secondary will be energized.)
MadDog- Hide quoted text -

- Show quoted text -

Very good idea.

TMT

.

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