motor contactor terminals fused together
motor contactor terminals fused together
(OP)
I have a report of two of the three motor phase terminals in a motor contactor being fused (shorted by melting) together. Twice in a row, same machine, same motor, same phases.
This is on a machine in the field. I was thinking it could be a short in the motor windings. We are operating 460VAC, 3phase.
What do you think?
Also, as far as testing, I guess we could compare resistances across the phases?
Any suggestions?
This is on a machine in the field. I was thinking it could be a short in the motor windings. We are operating 460VAC, 3phase.
What do you think?
Also, as far as testing, I guess we could compare resistances across the phases?
Any suggestions?





RE: motor contactor terminals fused together
RE: motor contactor terminals fused together
So either the report you received was completely wrong (likely) or your entire system is completely hosed and you need an Engineer to investigate it and redesign EVERYTHING about it.
I think it's more likely that your CONTACTS of one phase are welded, not the terminals. Contact welding can result from numerous causes, so still, more information would be needed, but check it out yourself and get the correct story.
"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington
RE: motor contactor terminals fused together
=====================================
(2B)+(2B)' ?
RE: motor contactor terminals fused together
Dunno Pete, how likely would that be? I have experienced the terminal connectors at motor fusing together on the older German machines, one would come loose and the two phases would arc but never seen two contacts fuse. I think Jeff's right on the money here.
Chuck
RE: motor contactor terminals fused together
I appreciate your time and input more than I can say. Have reached out to my customer/contact for more info.
Will have a conversation and continue post with more details.
Thank-you.
RE: motor contactor terminals fused together
One cause is a short circuit. This tends to produce welding, but not always.
Another cause is a heavy load or short drawing the voltage down until the contactor drops out. The voltage recovers and the contactor pulls in. Often seen with standby generators with too much A/C load. The cycle repeats until either the protection clears the circuit or there is not enough contact left to complete the circuit. But again, not always.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: motor contactor terminals fused together
=====================================
(2B)+(2B)' ?
RE: motor contactor terminals fused together
=====================================
(2B)+(2B)' ?
RE: motor contactor terminals fused together
"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington