Fault level contribution by a generator.

[PUNGLU]

We have a gen set consisting of a 5oo MVA generator and a 0.415/11 kV Traffo. The generator has Xd'= 15.9 %, Xd''= 11.1 %. The Traffo has z = 4.58%. I have calculated the fault level but its too high.

May be there is something I have forgotten and please remind me which of the generator reactances is appropriate

Thank you guys in advance.

 

[ScottyUK]

A 500MVA set directly connected to a 0.415/11kV transformer? Check your post and confirm the data you posted - something does not sound quite right.


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If we learn from our mistakes I'm getting a great education!

 

[PUNGLU]

Connection to the tarffo is via a circuit breaker

 

[GTstartup]

Still makes no sense. A 500MVA Generator at .415kV??

 

[slavag]

Hi Punglu.
Maybe it's 500KVA!!! Please see again Scotty's post.
Regards.
Slava

 

[PUNGLU]

Oops sorrry for that, its 500kVA!!!

 

[tem1234]

For calculate fault current, you should use Z"dv, so X"d = 11% in your case. For this size of generator, you can take typical value of X/R of induction motor, approximately 15-20 for 500kVA