Formula to calculate Line to Ground fault current?

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anbm

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TX
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Designer
Is there a formula to calculate Line to Ground (L-G) fault current at utility bus
if we know Three Phase (3P) fault current?

Talked to one of SKM supported persons, they said an estimate result will be L-G = 3P/3. I doubt about it, does anyone has any ideas?
 
Utility companies can always give you that info, or at least the numbers that will allow you to calculate it.

Your dealing with unsymmetrical faults when talking about SLG fault current, and SLG fault can sometimes be greater than 3ph fault currents, so, estimating by saying 1/3 is not a preferable choice, IMO anyway.
 
At the source terminals or with a short supply length there is often higher line to neutral fault current then there is line to line.

Impedance of the conductors makes all the difference, and when you consider the line to neutral voltage is only 50-60% of the line to line voltage that has some impact as well. Lower voltage across the impedance will result in lower current.
 
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