Generator short circuit calculation

[Harry choi]

I simulate 6.6kV generator's short circuit calculation in ETAP.
Generator capacity is 3,900kW and rated voltage is 6.6kV.
When I simulate SC, SC is just 2.7kA.
I know that Short circuit calculation use the X''d
If generator has small X''d, is that right generator's SC is small like this?

 

[davidbeach]

Seems low. Beyond that you'd need to share more data.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[waross]

I calculate an X"d of about 12.5%
As the X"d goes lower, the short circuit current goes higher.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[FreddyNurk]

Check that ETAP is reporting the correct fault figure. Its been a while since I'd used ETAP, but I seem to recall that it can report different figures (I''k, I'k etc).
Although waross' calculations tend to indicate the figure is correct, at least based on my recollections for this size of machine.

EDMS Australia

 

[davidbeach]

Probably spoke too soon on my first post. Actually picking up the calculator and pushing a few buttons, I come up with something in the 2.8kA range making my assumptions for the missing data.

I’ll see your silver lining and raise you two black clouds. - Protection Operations