dinkelja
Electrical
- Dec 10, 2004
- 31
I was intending to use LPS-RK fuses to replace FRS-R type, for some FVNR starters (10-40hp), vfd's (40hp), & SMC's (125-150hp) all 460V. According to NEC 430.52, size time-delay fuses at 175% of full load current. I have no nameplate information from the motors, so I assumed that FLA = FLC for this purpose. Should I assume some correction for pf or sf?
Then, are there additional considerations for sizing overcurrent protection (fuses in this case) specifically for VFD's or Soft Starters? My thoughts were not really; at some time the device might be bypassed and a full voltage start attempted.
Okay, I have been using the next standard size fuse above 175% FLA (not to exceed 225% of course) sound okay? Other discussions involve disconnects, I say next standard size above 115% of FLA, they say next size above the fuse rating.
Just looking for a quick confirm/deny or advice on the above. Thanks.
Then, are there additional considerations for sizing overcurrent protection (fuses in this case) specifically for VFD's or Soft Starters? My thoughts were not really; at some time the device might be bypassed and a full voltage start attempted.
Okay, I have been using the next standard size fuse above 175% FLA (not to exceed 225% of course) sound okay? Other discussions involve disconnects, I say next standard size above 115% of FLA, they say next size above the fuse rating.
Just looking for a quick confirm/deny or advice on the above. Thanks.