shoet circuit calc.

[Toros]

Hi, Do you know what is the worse, infinite avail. short cir. current at my 800A-480/277v service that would be provided By Dwp of San Pedro, CA???Where can I check this????Thank you

 

[augie47]

You might find this booklet helpful for you AIC questions:
http://www.cooperindustries.com/con...ry/selecting_protective_devices_handbook.html

 

[kingpb]

Hi, Do you know what is the worse, infinite avail. short cir. current at my 800A-480/277v service that would be provided By Dwp of San Pedro, CA???Where can I check this????Thank you

2 choices - Call the utility and have them tell you.

Second option, go out to the transformer and look for the nameplate. On it there will be an impedance value, then use the following formula to determine max possible SC:

Rated KVAxfmr / impedance = Max MVAsc

Ex: 150KVA xfmr, Z = 2%

150KVA/0.02 = 7500KVA

You can now calc the SC current at 480 volt. In this example it would be 9000A.