Motor Failure Cause
Motor Failure Cause
(OP)
If I have a motor failure and the breaker was tripped and one pole contact of the 3pole contactor is welded, what would be the possible cause? ground fault? single phasing?
If a motor trips during running and at normal current, I am under the impression that it is caused by excessive heating due to mechanical failures like bearing temperature...any other possible causes?
If a motor trips during running and at normal current, I am under the impression that it is caused by excessive heating due to mechanical failures like bearing temperature...any other possible causes?
GO PLACIDLY, AMIDST THE NOISE AND HASTE-Desiderata





RE: Motor Failure Cause
I'd suggest a basic megger test on the motor windings as a first step.
It could be a lot of things. The welded contact could indicate that it tried to open under fault conditions, or maybe it welded closed the last time it was started.
RE: Motor Failure Cause
The motor overload relay should not trip if running with normal current. So, something like an interlock or a winding temperature relay had to cause the trip.
RE: Motor Failure Cause
Generally though, LionelHutz would be right. Single phasing or a phase-to-phase fault would likely show 2 poles damaged. Contactor chattering can sometimes cause contacts to weld, but if only one pole was welded as a first point of failure, that would not usually cause the breaker to trip because there would not be a complete circuit path for anything to cause the trip.
RE: Motor Failure Cause
If during normal running condition single phasing occures motor will damage as one of pole is stuck.
RE: Motor Failure Cause
GO PLACIDLY, AMIDST THE NOISE AND HASTE-Desiderata
RE: Motor Failure Cause
You might make a more educated guess with careful testing and inspection of the failed motor along with gather details such as whether motor had just been started, any available trends of winding temperature, vibration trends etc. Cut the coils apart at the location of the failure and other similar locations to check for voids in insulation etc.
And there really is a lot more you can look at and analyse. And even gathering all that data, the best you can do is usually a guess.
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor Failure Cause
One case I've seen was tripped on a 87 relay.
RE: Motor Failure Cause
RE: Motor Failure Cause
A turn-to-turn fault can involve only one phase.
RE: Motor Failure Cause
RE: Motor Failure Cause
RE: Motor Failure Cause
RE: Motor Failure Cause