Exciting current of Extended-Delta Transformer?

[jimbofitz]

I am interested in seeing differences in excitation current of a standard transformer (Delta or Wye primary)to that of an extended delta unit.

Additionally I want to investigate any differences between a 3-leg transformer and a 5-legged unit under inrush and short circuit conditions.

If you haven't guessed yet I'm tasked to evaluate a 5-legged, extended delta primary transformer under inrush.

Anybody that might have a waveform capture or a useful link it would be appreciated!

Thank you in advance for your support.

Regards,
Jim

 

[davidbeach]

"Extended Delta" - that's a new one to me, care to explain?

 

[jimbofitz]

Sure,

It is a delta primary with "teasers" to provide a phase shift on the primary for rectifier transformers. In my case, a 7.5 degree shift is obtained.

A picture is worth a thousand words, so i have atatched one to look at.

 

[ScottyUK]

David,

My understanding is that it is a delta-wound transformer but the delta connection is formed by connecting the end of one winding to (say) the 80% tapping of the next winding. The lines are connected at the 100% tapping. The transformer produces a phase shift which is somewhat dependant on the tapping at which the delta is formed. They usually turn up in high power rectfiers with high pulse counts - 24 and upward.

The star-delta dual of the extended delta design is the zig-zag or inter-star transformer.


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

 

[davidbeach]

Thanks. No problem with the concept, just never heard the term before. Never worked with one so I can't be of help on the original question.