I'm looking at several different fault current tables for single phase XFRs and I see several different values for similar sizes and %Z. Three phase calcs seem straight forward (i.e. 3P bolted fault for a 500kVA 277/480 5%Z is about 12,028 amps). I have a table in front of me saying that a 1P...
Fellow Engineers,
According to the second edition of the Distribution Transformer Handbook (pg. 49, Richard Alexander), when a lighting tfr and a power pot are both feeding a load, he says to close the lighting tfr first when going on-line....and open the lighting tfr last when going off-line...
When intalling a new power transformer, it seems every engineers rule of thumb is to let it 'soak' for a day or two before loading the bank. I understand why it is a good idea to practice this rule (i.e. sudden change in temp., windings may have been damaged during the move, oil dispacement...
I'm looking for reference material on 3 phase transformer backfeed. For instants, I had a three phase bank 120/240 (gnd Y/closed delta...75/37.5/37.5 kVA) and lost one phase on the high side of the bank. Oddly enough, the phase that the cutout had isolated was actually at a higher voltage then...
Is anyone in this forum using the Elastimold 166FLR fused loadbreak elbows for sectionalizing light duty underground taps? If so, I would like to discuss the problems (if any) they've encountered in their application.
Please leave an email address or a contact number.
Thanks in advance.
Hello Fellow Engineers,
I'm looking for an exact reference to the situation of blowing a high side fuse on a delta-wye(gnd) connected power transformer(single phasing). From experience I know that when this occurs, the result is about a 1/3 voltage drop on the low side phase-neutral...
I'm looking for the 'K' factor for a S&C SMU-20 fuse link. At one of my rural substations I'm using 65E (Slow) fuses for my high side protection and 3 single phase 50A type E hydraulic reclosures (1A-3B)on the low side for feeder protection. I've been using page 111 of my Cooper...
I'm looking for means other than VFI (vacuum fault interupters) to sectionalize taps off undergound main-line feeders. VFI's work great for large subdivision applications but are NOT cost effective for single service taps. Does anyone know of a manufacturer that carries some sort of a fused...
I'm looking for the most common philosophy on fuse sizing for distribution taps (12.5kV system). In general,are most utilities sizing fused taps according to load or for maximum coordination with upline devices. Example: A single phase overhead tap off the main feeder 10 spans from the sub...
