Single Phase Short Circuit Spreadsheet

[jbt260]

Once upon a time, I downloaded an EXCEL spreadsheet from the "FREE STUFF" section of the website. The file was called "faultcalc.xls". It was authored by John Sokolik, Ver. 4.00.

I use this spreadsheet when I need to do a quick short circuit study for a 120/240V, 1ph system. Has anyone ever used this spreadsheet and verified it's accuracy?

For L-N calculations, the SC value appears to get higher as you go point-to-point downstream. This doesn't make sense.

I checked to see if this file is still in the "FREE STUFF", but noticed it is no longer there.

Looking for thoughts and/or opinions.

Thanks,
Jeff

 

[bob]

For L-N calculations, the SC value appears to get higher as you go point-to-point downstream. This doesn't make sense.Jeff

When you have a line to neutral fault you have the full primary winding involved but only half of the secondary winding. The impedance of the half
winding condition is different from the full winding. Therefore you must make an adjustment to %R and %X. The multiplier usually is 1.5 x full winding %R
and 1.2 time full winding %X. When the calculations are completed
the KVA fault is divided by 120 volts rather that 240 volts giving a higher
amperage fault.

 

[jbt260]

Thanks for the reply Bob.

I recently realized that a L-N fault is greater than a L-L fault on a 120/240V system. I had always assumed that a L-L fault would be higher.

Have you ever used the spreadsheet I mentioned in my original post? I am trying to find someone who has used the spreadsheet. I use this spreadsheet for my 120/240V fault calcs. I think there may be an error in the 120V fault calcs as you go downstream from the source.

 

[bob]

I recall the spreadsheet program but never used it. You might send an email to Mike Holt and ask him. He may know who wrote it.