X/R ratio for single phase to ground fault

[musaUKPN]

Hi,

I know that we use X1/R1 for X/R ratio in case of three phase fault. I want to know what will be the X/R ratio for single phase to ground fault?

Can I use (X1+X2+X0)/(R1+R2+R0)?

Regards,

musa UKPN

 

[magoo2]

Yes, the equation you have is based on the interconnection of the 3 sequence networks for a single line to ground fault and will result in the equivalent X/R ratio for this condition.

 

[healyx]

I'd say that would be correct. What are you using the result for? Is it to determine thermal equivalent current for the fault?

 

[davidbeach]

If you are using it to compute duty of ANSI rated circuit breakers you actually have to calculate the X using an X only network and the R using an R only network.

 

[musaUKPN]

Many thanks for your valuable comments.

musa UKPN