I am doing arc flash calculations for the first time and am using a short circuit software. I have one 13.8KV bus, protected only by a fuse, that produces an incident energy of only .4 cal/cm2 under a three phase fault current of 12.49KA. Basically the FCT is only .01 seconds. I know that there are many more parameters that come into consideration than what I am listing, I am just wanting to know if this is possible. It seems to me that if this is the case, 13.KV would not be any more dangerous than 480V in terms of arc flash.
Arc Flash Calculations
- Thread starter derek22r
- Start date
- Status
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
This is not un-normal.
davidr43229
Senior Member
- Location
- Columbus, Oh
You need to know the fault current available and the total clearing time of the Overcurrent protection device, including the .01 of the FCT, that will tell the tale.
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
The resulting arc flash fault current in your situation (@ 13,800V) is a very high percentage of the bolted fault current. That is why the fuse picks up so quickly.
Bolted fault current was 12.49kA and the arc flash fault current calculates to 12.08kA.
Bolted fault current was 12.49kA and the arc flash fault current calculates to 12.08kA.
davidr43229
Senior Member
- Location
- Columbus, Oh
I calculated 3.82 Cal/Cm2 at 18", .95 at 36", from a visteon calculator. I used the 12.47KV, and 12.5KA available. Surprising that it only equates to a Level 1
- Status