Power Transformers Vectors Group 3

[ARAMCAWEE]

Guys,

I've been searching the net for a full description of all vector groups for power transformer without success. I've got one site with some of the group and a daigram showing the difference but not all of them. Dose any body aware fo such site??

Thanks

 

[busbar]

See: thread238-76446 thread238-79243

http://www.siemens.com.mx/PTD/downl...ide/Contents, Introduction, Product Range.pdf

http://www.mss.de/eng/stromversorgungen/produkte/pdf/gr3e-inh.pdf

 

[ScottyUK]

The J&P Transformer Book has illustrations of a huge number of transformer vector connections. It doesn't cover all the possible groups for specialised applications such as multiphase transformers for very large rectifiers, but it does show virtually everything else you will encounter. It's also an invaluable reference for all your other transformer questions.

 

[davidbeach]

ScottyUK - What is the J&P Transformer Book? Thanks.

 

[ScottyUK]

Hi David,

The "J&P Transformer Book" is a very good general reference text of 900-odd pages which covers pretty much all aspects of transformers to a reasonable depth without going into the great detail found in more specialised works. It's a useful book to have on the shelf.

"J&P" dates back to the original edition by Johnson & Philips published in 1925.

ISBN 0-7506-1158-8



-----------------------------------

Do it right, or don't do it at all.

 

[ARAMCAWEE]

Thank you all for your inputs. The reason I was looking for the Vecotr Groups is that I'm facing a proplem in my work. We have built a new Centeral Control Room that shall be feed through new substation. The new substation (S/S M) is a duble ended, with two feeders from two different sources and a normaly open bus tie. The first source, (Incomer A) is from bus # 400 13.8KV through DY1 transformer (13.8/6.3KV) to S/S 100B, then from S/S 100B to S/S M through DY11 transformer (6.3/0.4KV)The second feeder (Incomer B) is from bus # 300 13.8KV to (S/S N)through (13.8/0.4KV) DY1 transformer.

Now, due to the difference in the Transformers vecotr groups, is it possible to parell the two incomers without having any problem? if not, what is the most preactical soultion to such problem?

 

[bigamp]

If your two incoming 13.8kV supplies are in phase then the two 400V supplies will be out of phase with each other and you will not be able to parallel them.

The 400V supply derived from the 13.8/6.3kV - 6.3/0.4kV will be in phase with the 13.8kV supply. The other 400V supply, derived from the 13.8/0.4kV transformer, will be 30 degrees out of phase (lagging).

You would need to fit protection at the 400V system to prevent paralleling. This could be mechanical in nature (keys) and also electrical (check sync permissive).

Probably the best solution to allow paralleling would have been to have the 13.8/0.4kV transformer as a Yy vector group. Alternatively, the 6.3/0.4kV transformer could be a Yy vector group. If you already have the transformers and are (naturally) reluctant to change them, you could possibly fit in a 0.4/0.4kV Dy11 transformer between the 13.8/0.4kV transformer and the 400V switchboard.

Do check the two 13.8kV incoming supplies though, as it is possible that they could be derived from different sources and they could be the right vector groups for you. If the 13.8kV that supplies the 13.8/0.4kV transformer is 30 degrees in advance of the other 13.8kV power supply then your two 400V supplies will be in phase and all will be well.

Concur with ScottyUK re the J&P transformer book; its a classic and well worth having. There is a new edition available from Newnes. Alternatively, you can get previous editions from the 2nd hand book market.

 

[jbartos]

Comment: The transformers:
Dy1 and Dy11 have relative voltage displacement of 60° rather than 30°. Therefore, any corrections of angle displacement will have to consider 60°.

 

[jbartos]

Suggestion: Visit

http://www.siemens.fi/evu/ev/download/peg97/pegt04.pdf

etc. for vector diagrams