Vector Groups for Transformers

Please search for 'Vector Group' in this forum and you will find lot of valuable information which will help you to find the answer. The most recent posting for Vector Group is http://cr4.globalspec.com/thread/35957#comment374937

- MS

Dear all,

Probably, Dyn11. But make sure what is the standard in your area or country.

Regards

@ akihito

how u decide Dyn11.

I agree to Akihito' selection of Dyn11.

I think by 6.6/415v you meant 6.6KV/415V

From this voltage system, it seems you may not have neutral in HT side but have it in LT side (for single phase use). So in 6.6KV side Δ should be fine but in 415V side, you must need Y with neutral. So Dyn is your selection. The phase lagging (last numerical digits) doesn't matter to you if you don't use it in parallel but 11 is most common. So, Dyn11 is ok on this basis.

If you would like to use it in parallel with any existing transformer, you must select it with the same vector group of the existing one.

Hope you understand.

- MS

@ msamad

If i want to use it in parallel then how phase lagging affect it?

Then, there will be a voltage difference between the same secondary phases of the parallel transformers and both transfomers will be damaged (or tripped by the protection as soon as it is energized).

-MS

How voltage difference B/w the same secondary if they have same vector group t.i

Dyn1?

Boss, its wont affect if the vector group is same for both transformers connected in parallel....

He has discussed the case if the transformers are of different vector groups.