Multiple motors on same feeder issue
Multiple motors on same feeder issue
(OP)
I had (13) 20hp,480volt 3phase motors running at the same time . The 480volt feed terminates at a tap block which then feeds fuses for each motor, contactor and ol's.
15 fuses feeding 5 motors blew.
That left me with 8 motors running.
Only 1 of the 5 motors was identified with a problem no continuity phase to phase.
The other 4 motors fuses were replaced and have been running ok.
The fuses that blew were mounted adjacent to each other on a din rail.
If 1 motor has a open winding could this have caused all 15 fuses to open?
The fuses are 45amp LPJ.
Thanks
15 fuses feeding 5 motors blew.
That left me with 8 motors running.
Only 1 of the 5 motors was identified with a problem no continuity phase to phase.
The other 4 motors fuses were replaced and have been running ok.
The fuses that blew were mounted adjacent to each other on a din rail.
If 1 motor has a open winding could this have caused all 15 fuses to open?
The fuses are 45amp LPJ.
Thanks





RE: Multiple motors on same feeder issue
If one leg has a different voltage than the others, the voltage imbalance can cause large current imbalances that could result in what happened.
A failed motor winding could precipitate this. It could also be a loose connection causing a brief single phasing of the whole bus that could blow lots of fuses and damage motors.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Multiple motors on same feeder issue
Probably, but given the variety of fuse types available and not knowing your system topology it's not possible to say for sure.
Again depending on the system layout, don't be surprised if you start having random fuse failures on other motors. If you do, replace all three fuses in a group, not just the failed fuse(s). Even though all three fuses may not blow on a motor fault, the fuses that seem to have survived are often damaged by the surge that blew the other fuse(s) and may no longer be able to withstand normal duty.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Multiple motors on same feeder issue
Then they get frustrated and start putting in bigger fuses...
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
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RE: Multiple motors on same feeder issue
Keith Cress
kcress - http://www.flaminsystems.com
RE: Multiple motors on same feeder issue
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Multiple motors on same feeder issue
----------------------------------
If we learn from our mistakes I'm getting a great education!
RE: Multiple motors on same feeder issue
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Multiple motors on same feeder issue
----------------------------------
If we learn from our mistakes I'm getting a great education!
RE: Multiple motors on same feeder issue
thanks