What is a T-wound transfromer 1

[bozzah]

On a job, a designer stated that T-wound transformer cannot be used (This a dry-type 600V-208/120V Delta-Wye,3PH,4W configuration).
However, what is T-wound configuration and what are disadvantages/advantages of this type of winding.

 

[ScottyUK]

Look for a Scott transformer (no relative of mine, I don't think) on Google. The configuration uses two transformers to derive a pseudo-3-phase supply from a two phase + earth system.


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If we learn from our mistakes I'm getting a great education!

 

[cuky2000]

See the enclosed link

http://cuky2000.250free.com/Transformer_Connection_2.gif

 

[davidbeach]

Not really the same as the Scott T mentioned by ScottyUK and cuky2000.

In small kVA sizes (up to 9 or 15kVA) the default 3-phase transformer is often a T-T rather than a [Δ]-Y. The T-T needs two sets of winding rather than three. One winding is rated for phase-to-phase voltage, is connected phase-to-phase, and has a center tap. The other winding is rated 86.7% of phase-to-phase voltages, has a tap 42.3% from one end, and is connected to the center tap of the other phase with the tap closest to the end connected to the center of the other winding. (Hope that makes sense.)

Only two windings instead of three.

The portion of the second winding between the two taps sees more load current than the rest of the winding.

No delta winding.

Neutral isn't from a wye point, but rather from a tap in a winding.

 

[bozzah]

thanks all.

Davidbeach,
I did not quite understand how you make the connections.
So, what would be a disadvantage of the this arrangement? Would the fact that part of the winding sees more current than the rest of the system be one of the issues?

thanks.

p.s. Is there a diagram somewhere on the net for this connection.

 

[davidbeach]

Go to

http://tinyurl.com/289em2

and click on the top item in the search results list.

 

[bozzah]

What would be disadvantage of T-would transformer? Are there any known problems when compared to standard delta-wye?

thanks.

 

[davidbeach]

The last four sentences of my 6 Nov 07 20:00 post are the differences, they could be advantages or disadvantages depending on the application. Hard to say without knowing the details. Do you need a delta winding to trap 3rd harmonics? Then the lack of a delta would be a disadvantage. That type of thing.