Single Phase Arc Flash

[eeprom]

Hello,
I have been asked to do an arc flash study on a small single phase system, a 75 kVA transformer, 1 phase, 240VAC. ETAP uses three phase for arc flash. If I do the study using 3 phase, the fault currents will be smaller, because a single phase 75kVA will produce greater fault currents than a 3 phase. Any ideas on how to get this accurate?

EE

 

[ZeroSeq]

You will need to conduct the study using the unbalanced module in order to accurately calculate the fault currents and their associated fault clearing times.
As there are no single phase empirical formulas provided in IEEE Std 1584, the three phase empirical formulas can (and are) used as a conservative estimate (using the single phase arcing fault current and clearing times)

 

[eeprom]

Thank you ZeroSeq. That's good information to know. I'll try that. I tried to run ETAP's single phase AF study and I came up with ridiculous numbers.

 

[Skythian]

google ARCMASTER software