i found that IEEE 1583 provides the gap and distance information for 15kV below.May i know how to find the gap between conductors (mm) and distance, x factor for 33kV and 132kV?

Thank you....

Above 15kV, you can't use the IEEE equations based on the stuff they blew up and the associated statistical analysis.
You must use the theoretical IEEE equations which is simpler and doesn't have the X factor and gap.

Dear Vincent,

Sorry that i didn't get your point. Do you mind to mention the theoretical IEEE equations which are used to calculate the incident energy for the 33kV and 132kV? Thousand thanks.

Yuna

See Equations D.7.4 and D.7.5(b) in Annex D of NFPA 70E-2009.

Dear Vincent,

i only manage to download the IEEE 1584 from my university. I fail to get the NFPA 70E-2009. can you write up the equaption? where can i manage to get the NFPA 70E? Thanks a lot...

There's supposedly a view-only version available from the NFPA (http://www.nfpa.org). Else you can buy it (pdf or paper) at the same location.

I never had access to the full IEEE 1584, only what is quoted in NFPA 70E. So I can't tell you what are the equations number in it.

check Help file for Arc Flash Analytic v5.0 for 15kV+ system equations.