Transformer in-rush

[DavH]

How do I determine the affect of in-rush current on two parallel 6.6KV 2MVA generators from 2 x 2MVA and 2 x 1MVA transformers. The generators will be up to speed before attempting to take any load and the four transformers mentioned will have minimal load ie <10%.

 

[RRaghunath]

The inrush is like a fault and can severely pull down the voltage, but for a few cycles (typically 100ms), considering your generation is limited.
If you are planning of fast changeover, ther is no need to woory about inrush. If you are energising one transformer at a time, then also you should not have any concern.
In any case, it is advisable to keep the generator excitation in "Voltage control" mode before connecting/transferring the transformer.

 

[DavH]

Thanks ragun!

 

[7anoter4]

Try also :

http://www.ipst.org/TechPapers/2005/IPST05_Paper140.pdf

May be useful.