NCEES 518

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Chicago and jdd: Both of your methods look like they work. I personally use the method jdd is using because I find I make fewer errors that way (in chicago's method I always forget if it's Sold/Snew or Snew/Sold). But as always, you should use whatever makes the most sense to you.

Cabby: looks like you've hit the nail on the head. I've always calculated per-unit problems on a phase basis too (it takes more calcs, but I have to remember fewer equations that way).

 
Maybe I'm over-simplifying this, but I just used eqn 28.11 from EERM (basic equations for xfmr turns ratio): IpVp=IsVs, then solved for Ip=Is*Vs/Vp=75.93A*132kV/13.2kV=759.3A

 
Maybe I'm over-simplifying this, but I just used eqn 28.11 from EERM (basic equations for xfmr turns ratio): IpVp=IsVs, then solved for Ip=Is*Vs/Vp=75.93A*132kV/13.2kV=759.3A
You're not oversimplifying it at all for the solution to the problem in the NCEES book. This thread just took a right turn into PU analysis since that particular problem/circuit is a good example for use in playing with the concept.

Jim

 
You're not oversimplifying it at all for the solution to the problem in the NCEES book. This thread just took a right turn into PU analysis since that particular problem/circuit is a good example for use in playing with the concept.
Jim
Oops, okay. Sorry for just jumping in on the discussion!

 
Hello,

I wanted to revisit this problem since I am a bit confused on the terms used. I calculated the load current in the generator as the full load current: 

IGen=50MVA/(sqrt3*13.2kV)=2187 Amps

and chose this answer which turns out is wrong. Why is this  answer not right?

 
LOL.

Grave Digger!

th


 

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