I'm trying to figure out how to quantize the circulating current for a no load scenario given the following specifications:

2.5/3.125 MVA 46.2/4360KV 6.5%Z and
2.5/3.125 MVA 46/4330KV 6.3%Z

I have estimated the circulating current to be somewhere around 2.5 Amperes. Please let me know if anyone comes up with a different answer.

Can this difference in %Z really cause a major concern to my power system at start-up, at motor start-up, or at normal running conditions?

Thank you!

 

Juan Carlos... ignoring losses and X/R values, I calculated 6+ amperes. For a more exact value the no-load secondary voltages and no-load losses must be known.

It is unlikely these values will be found on the transformer nameplates, but they should be available from the FAT (Factory Acceptance Test) documents.

Regards, Phil Corso (cepsicon[at]AOL[dot]com)

 

Juan Carlos... If transformer's Vector-Group is Yd or Dy, then circulating-current is dependent on Turns-Ratio. If Yy or Dd, then Voltage-Ratio is used!

Regards, Phil Corso

 

Juan Carlos... using your values and ignoring any vector group having a 30 deg displacement, there is a circulating current in the secondary windings of 19.2 Amperes!

Regards, Phil Corso

 

> I'm trying to figure out how to quantize the circulating current for a
> no load scenario given the following specifications:

> 2.5/3.125 MVA 46.2/4360KV 6.5%Z and
> 2.5/3.125 MVA 46/4330KV 6.3%Z

your specifications given are doubtful...
4360KV...??
and 2.5/3.125MVA...??
plz recheck it and confirm.