Dzn0 Transformer Explanation 2

[jpflying]

Can somebody please help me by explaining how a Dzn0 tranformer is wound or operates. I understand the delta connection, but what is the z winding???? How is a z winding wound and what does it do?

Thanks

 

[prc]

Dzno means that HV is delta connected,LV is zig-zag connected, n means the neutral of the zig-zag connected winding is brought out, 0 means there is no shift between voltage vectors of HV and LV. Zig-Zag connection is modified star with 50 % of the winding in U phase and balance 50 % winding will be in W phase,both sections series connected with neutral formed from W phase section end.( similarly 50 % of V phase + 50 % U phase etc)

The reason for Z winding in this case may be to get zero shift between HV &LV( In a delta/star connection there will be 30 degree shift between primary and secondary).Yz connection is used so that a stabilising delta winding can be avoided.

Z winding is also used to get a neutral earth in an other wise unearthed system ( eg Grounding transformer with Z winding)

 

[rcw retired EE]

Search for "zig-zag winding" for some good explanations.

 

[jpflying]

Thanks you for the information.

I have seen zig-zag transformers used to develop a neutral in an un-grounded system.What is the advantage of the zig-zag winding compared to a simple star winding when purchasing a new transformer?

Thanks

 

[rcw retired EE]

One advantage is zero phase shift betwen HV & LV but still have a grounded neutral LV system and isolation between HV & LV ground fault currents like a normal delta-wye.

 

[jpflying]

Thanks for the information and now understand.