Re: Spawning a 12 pulser

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Crow Leader by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla-at-lists.symmetric-dot-net>

According to GE "Distribution Transformer Manual" section on wye to wye
three phase transformers-

"This transformer, if of the three-legged, three-phase core type, should not
be used in applications subject to sustained phase-to-ground faults,
unbalanced loadings, loss of one primary phase or other unbalanced
conditions. this is because the magnetic characteristics of the transformer
will permit current to circulate in the tank under certain operating or
fault conditions which cause tank heating."

The associated diagram is just a three phase transformer and info on where
to hook leads up.

KEN


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, August 15, 2002 4:42 PM
Subject: Spawning a 12 pulser


> Original poster: "Finn Hammer by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<f-h-at-c.dk>
>
> Guys!
>
> I decided that, since this is perhaps going to be the last transformer
> that I wind, (in these fast moving OLTC days :o)  ) I would be a
> complete a**, if I did not wind it to conform with a 12 pulse supply,
> even though I have quite a few questions about it. I`l take one at a
> time.
>
> Looking at this link:
>
> http://www.elec-toolbox-dot-com/usefulinfo/xfmr-3ph.htm
>
> I am informed, that it is a bad thing to run a 3-phase transformer in
> WTE-WYE mode. That means connecting both the primary windings as well as
> the secondary windings in WYE, or "star" as we say overhere, due to
> problems with "harmonichs" and balancing.
>
> The 12 pulser transformer has secondaries connected in both WYE as well
> as Delta, so taking the advise seriously would mean, that I am
> restricted to connecting the primary in Delta.
>
> This is not a bad thing all together, but I would get a more versatile
> transformer, if I could also hook the primary in WYE, so I need to ask:
>
> Does anybody here know, what these harmonic and balancing problems
> really mean, can it lead to runaway conditions, is it a serious problem
> or just some theoretical nitty gritty?
>
> Cheers, Finn Hammer
>
>
>
>