Generator SLG fault current vs. ISC 3p
Generator SLG fault current vs. ISC 3p
(OP)
I recieved a cut sheet from a gen manufacuter and told him to comply with ANSI C50.13 which will limit the ground fault current Isc SLG to a value less than or equal to the 3 phase fault of the generator. My comment was to increase the zero sequence impedance 3x's the value of my positive sequence. My direct axis subtransient is .13pu, X2=.19pu and my X0=.02pu
2500kVA
480/277
His response: That standard only applies to generators 10MVA and larger. Not necessary for a generator of this size.
2500kVA
480/277
His response: That standard only applies to generators 10MVA and larger. Not necessary for a generator of this size.






RE: Generator SLG fault current vs. ISC 3p
RE: Generator SLG fault current vs. ISC 3p
Since that standard applies only to machines 10MVA (c50.13) larger,
Q1- So is there a standard for lower machines?
Q2 - Also do I need to provide more zero sequence impedance to account for the low zero sequence impedance on the generator?
Q3 - What does the industry do? I see a lot of generators that have a really low zero sequence and I don't see any impedances added to them?
RE: Generator SLG fault current vs. ISC 3p
I would ask the generator manufacturer to verify that the generator is adequately braced for a bolted line-to-ground fault at the generator terminals.
For medium-voltage generators, they are usually grounded via some type of impedance.
David Castor
www.cvoes.com
RE: Generator SLG fault current vs. ISC 3p
RE: Generator SLG fault current vs. ISC 3p
Alan
"The engineer's first problem in any design situation is to discover what the problem really is." Unk.
RE: Generator SLG fault current vs. ISC 3p
Thanks a lot for all your responses
RE: Generator SLG fault current vs. ISC 3p
- MS