Regarding Generator sizing

In short:

subtransient reactance - determines generator fault current during the first few cycles of the fault (about 4 to 6 cycles typically).

transient reactance - determines generator fault current from about 4 cycles until about 5 seconds.

reactance - refers to the steady-state reactive impedance of the unit.

I have neither the time nor the patience for a more detailed explanation but I'm confident that someone else can explain more. I am also confident that you can easily find more information than you really want between the covers of almost any power systems text book.

I think most on this forum are willing to assist you in your efforts. However, that same group would like some effort on your part to try to answer you question before posting on this forum. If you would have use Google and searched for "generator reactance", you would have found the first listing as http://www.cumminspower.com/www/literature/technicalpapers/PT-6008-GeneratorReactances.pdf and you would have had your answer.

bheemsen_acharya1

Please respond.