Generator X over R ratio 1

[GreyGoose]

Is there an acknowledged method/calculation/table/curve for deriving the X over R ratio of any given generator? This value is needed for computer modeling of the generator (specifically, steam or gas turbines for my apps), but is not always included or available from the vendor (esp. during the design phase of a project). any tips, ideas, or references available?

 

[rhatcher]

GreyGoose, I am curious ....the X/R ratio of a generator is specific to the design of the machine. How would any info provided to you here help if you have no specific info on the generator in question?

 

[GreyGoose]

sorry for the confusion. I am looking for the methodology for deriving X over R ratio assuming you have a some generator data available. I found an approximate method in IEEE C37.013 (Generator Circuit Breaker):
assume X = x"d
assume R = X2v/(2*pi*f*Ta)
where
x"d is gen. subtrans. react.
X2v is gen. saturated neg. seq. react.
Ta is armature time const.
f is frequency
Unfortunately, I have not been able to verify this in another source or find a good (read better or easier) explanation for it. I understand than X over R is specific to a given generator design, but surely there must be some way of deriving that value from other design parameters. Thanks.

 

[rhatcher]

Thanks for the clarification. The IEEE is as good of a source as any. The question here (if any) is whether it is appropriate. The reference you gave is probably (I don't have it) related to calculating short circuit duty of the circuit breaker based on the generator parameters. As such, it seems quite appropriate to what I suspect you are trying to do.

Unfortunately, I cannot take the time now to provide more info as tomorrow is a holiday and I am starting to party as I write this. In fact, my wife is now tapping her feet as she waits for me to finish. I will come back though when I have my head straight. (Well, it is never straight, but you know what I mean.....) s-)

Happy 4th of July!!!!!!!!!!

 

[jbartos]

Suggestion:
1. IEEE 399-1990 or latest 1997 "IEEE Recommended Practice for Industrial and Commercial Power Systems Analysis"
Figure 151 "Typical X/R ratios of Generators. Generator scale is from 20 to 1000kVA and X/R scale is from 0 to 80. It is also good for synchronous motors.