Fault Currrent

[adavey]

I currently have 4-500KVA transformers per phase with an impedance of 5% per transformer. I just need some clarification how I would size the fault current for this ?????? The building in question is only going to have a main fused switch of 600Amps 3 phase 208V. Also, how would I calculate the available at the downstream Main Distribution Panel that is also 3phase, 208V 600A. I have not done this in a while. Any advice in the calcs ?????????

 

[zog]

I currently have 4-500KVA transformers per phase with an impedance of 5% per transformer. I just need some clarification how I would size the fault current for this ?????? The building in question is only going to have a main fused switch of 600Amps 3 phase 208V. Also, how would I calculate the available at the downstream Main Distribution Panel that is also 3phase, 208V 600A. I have not done this in a while. Any advice in the calcs ?????????

The calcs are easy if you assume infinite fault current from the utility, but that will cause you major problems down the line. Your fisrt step is to get this data from your utility.

 

[bob]

I currently have 4-500KVA transformers per phase with an impedance of 5% per transformer. I just need some clarification how I would size the fault current for this ?????? The building in question is only going to have a main fused switch of 600Amps 3 phase 208V. Also, how would I calculate the available at the downstream Main Distribution Panel that is also 3phase, 208V 600A. I have not done this in a while. Any advice in the calcs ?????????

Are you saying that you have 4 500 kva single phase transformer( total 12)
connected in parallel to each of 3 phases?

 

[bob]

Adavey
what happened to you.