We have a transformer of 4 MVA, its Vector group is Dyn 11 (11000 / 3300 volt) step down, load losses are 40.8 KW. If we use this transformer as step up, are the losses are same or will be increase?

 

Hussain... yours is an interesting question? The theoretical answer is, yes, losses are different. Why?

1) Neglect the effects of waveform, harmonics, and certain construction asymmetry (e.g., coil distance from the core.)

2) Input equals output plus losses.

3) Assume total core-losses are assigned to the supply-side winding.

4) Then losses are less if the HV-side (remember I^2R) is the source, than if the LV-side were the source.

5) However, from a practical viewpoint, the effect is negligible!

Regards, Phil Corso

 

are we calculate actual losses?

 

Hussain... typically, that information comes from the manufacturer.

Phil Corso

 

no... the losses will remain the same!
no difference!

 

Shoaib, you are correct if: the primary-winding and secondary-winding leakage impedances are equivalent; and 2) you are using an "approximate" version of the transformer model, that is, core-loss components are placed at the supply-source voltage terminals.

An aside to Hussain... are you sure load-loss is 40.8kW? What is core-loss?

Regards, Phil Corso

 

I think you must consider the isolation strength of the winding,.,.

 

Jimper... while dielectric-loss (insulation, oil) is measurable, it will not materially affect the outcome of the Hussain's question!

However, if I have misunderstood the point of your comment, please elaborate!

Regrads, Phil Corso