IEEE 142 calculations

[heberovchem]

Could someone show me the calculations to arrive at the following percentages:
The available ground-fault current should be at least 25% (X0 = 10X1) and preferably 60% (X0 = 3X1) of the three-phase fault current to prevent serious transient overvoltages. Available is considerably higher than the level of fault current desirable in a resistance grounded system.
Thank you

 

[7anoter4]

Sorry, heberovchem, but how your question is related to IEEE 142?

 

[heberovchem]

It is written on page 16. But I've already figured out. Thank you.

 

[budhiman]

Hi heberovchem. can you let me know what did you find?