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Author basic 3-phase transformer question
Ryan Evans

2007-03-08, 8:25 pm

If the secondary has a load on 2 phases but nothing on the third,
Will one phase of the primary draw nothing?

RE


Long Ranger

2007-03-09, 3:25 am


"Ryan Evans" <revans48162@comcast.net> wrote in message
news:-5mdnRgXse4_MG3YnZ2dnUVZ_viunZ2d@comcast.com...
> If the secondary has a load on 2 phases but nothing on the third,
> Will one phase of the primary draw nothing?
>
> RE
>Are you referring to phases, or legs? It takes two legs to get across a
>phase winding. If you are truly using two phases, the third one is implied
>also, since it takes three legs to get across two phase windings.



Steve Lockridge

2007-03-09, 9:25 am

On Mar 7, 3:49 pm, "Ryan Evans" <revans48...@comcast.net> wrote:
> If the secondary has a load on 2 phases but nothing on the third,
> Will one phase of the primary draw nothing?
>
> RE


Could you tell us what the primary and secondary vectors (connections)
are for this transformer?

Steve Lockridge
Alfa Transformer

phil-news-nospam@ipal.net

2007-03-09, 5:25 pm

On Wed, 7 Mar 2007 16:49:24 -0500 Ryan Evans <revans48162@comcast.net> wrote:

| If the secondary has a load on 2 phases but nothing on the third,
| Will one phase of the primary draw nothing?

That depends on the transformer phase configuration. I would expect a
WYE secondary for what you describe. But the primary could be WYE or
DELTA. If the primary is also WYE, then the 2 corresponding phases of
the primary will draw current, and the other will not. But if the
primary is DELTA, two of the primary _windings_ will be drawing current
with the phase in common between them having more current and the other
two phases having less.

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