bdn2004
Electrical
- Jan 27, 2007
- 794
Below is a TCC for a 2500kVA, 12.47kV-480V Delta-Wye grounded transformer and it's 150E primary fuse. This is the existing installation. The full load amps on that transformer is about 116A. The recommended size per the literature I've read says to size the fuse between 100-150% of the FLA = 116A*1.5 = 174A....So the 150E looks ok.
It can be shown that the arc flash can be reduced on the secondary main if that fuse is reduced to a 100E fuse and the transformer will still start. But this is less than 100% of the full load amp rating. On the other hand, looking at the fuse curve for that - which is on the second post - it doesn't look like the 100E would ever trip even at 116A.
Would this be a good idea ?
It can be shown that the arc flash can be reduced on the secondary main if that fuse is reduced to a 100E fuse and the transformer will still start. But this is less than 100% of the full load amp rating. On the other hand, looking at the fuse curve for that - which is on the second post - it doesn't look like the 100E would ever trip even at 116A.
Would this be a good idea ?