Use of wye/delta transformer

[Do You Like Ham]

What are the typical/practical uses of three phase wye (primary) / delta (secondary) transformer?

If one knew the loads on the secondary were going to be unbalanced (e.g., single phase loads of different power factor and/or load), would one still consider wye/delta? why or why not?

I’m struggling to find any reference as to how to compute the current on the primary line of the connection if the secondary is unbalanced. In fact, this reference states
“This is a degenerate case, and no unique solution can be found for computing the primary line currents from the secondary line currents (Try to find out WHY).”

Can anyone shed some light on the ‘why’?

TIA for any insights.

 

[xptpcrewx]

What are the typical/practical uses of three phase wye (primary) / delta (secondary) transformer?

If one knew the loads on the secondary were going to be unbalanced (e.g., single phase loads of different power factor and/or load), would one still consider wye/delta? why or why not?

I’m struggling to find any reference as to how to compute the current on the primary line of the connection if the secondary is unbalanced. In fact, this reference states
“This is a degenerate case, and no unique solution can be found for computing the primary line currents from the secondary line currents (Try to find out WHY).”

Can anyone shed some light on the ‘why’?

TIA for any insights.

Because with an unbalanced delta there is some amount of circulating current trapped within the delta connection which is not unique (infinitely many solutions).


Sent from my iPhone using Tapatalk

 

[texie]

I know of no practical use for a Y primary transformer for inside wiring. Yes, I know many think reverse feeding a step down delta/Y for a step up application is OK but I think it is a terrible idea on a number of levels.

 

[bwat]

Do a search on " Symmetrical components ". This is how you can evaluate unbalanced systems. Relatively math heavy.

 

[xptpcrewx]

I know of no practical use for a Y primary transformer for inside wiring. Yes, I know many think reverse feeding a step down delta/Y for a step up application is OK but I think it is a terrible idea on a number of levels.

Transformer connections have a lot to do with system grounding design. Unless you are working with some special application, stick with the standard connection types.

 

[synchro]

What are the typical/practical uses of three phase wye (primary) / delta (secondary) transformer?

A wye-delta is sometimes used as a grounding transformer, as is a zig-zag configuration. A wye-delta provides a low impedance on its input side to zero-sequence currents (i.e.,line current components that are in-phase with each other and equal in magnitude). This function does not depend on any loading on the delta secondary, although it can serve some loads if desired.