Generator reactance tolerances

[tefc]

Hello,

I'm currently performing a short circuit study.
For this calculations, the generators direct-axis subtransient reactance is required. At this stage, I know the expected value of this reactance (unsaturated & saturated value), however I've also to apply tolerance according to ANSI C50.10.

Could someone provide me with tolerance defined in ANSI C50.10. Thanks in advance.

 

[jbartos]

Suggestion: Please, would you be more specific about those tolerances defined in ANSI C50.10. This is not exactly a tolerance citing standard.

 

[kevd]

IEC is +/-15%. It is usually practice to take the -15% which gives the worst case reactance after factory test and gives the maximum possible current.

I cannot imagine ANSI is much different.

 

[tefc]

jbartos, kevd, thanks for your replies.

jbartos, my concern is I don't have the American Standards defining the applicable tolerance on the expected value of the direct-axis subtransient reactance (I assumed it was ANSI C50.10, but maybe I'm wrong).
As suggested buy kevd, I've used the IEC tolerance (-15%), but I've to perform my calculations according to American standards. So this is still an issue.

 

[RajT]

It should not be an issue if you state in your calculations all assumptions made.

 

[jbartos]

Suggestion:
1. IEEE Std 115 test generator for short circuit parameters. However, the Xd" accuracy is often specified in the generator spec, e.g. plus minus 10%
2. Visit

http://www.hq.usace.army.mil/cemp/e/Et/emergenc.pdf

and check with generator manufacturers
3. Military standards requires for the Xd" measurement that the generator speed tolerance is plus minus 1% and measuring accuracy is plus minus 0.5%.
See
MIL-STD-705C
24 April 1989
SUPERSEDING
MIL-STD-705B
26 June 1972
MILITARY STANDARD
GENERATOR SETS, ENGINE DRIVEN
METHODS OF TESTS AND INSTRUCTIONS