Motor Seized and Phase Open

[bwat]

Small 2HP motor had some type of failure or overload. After removing motor from the machine to troubleshoot, it was noticed that the shaft is locked up to the point that I can’t spin it with my hand while completely uncoupled to anything else. Also, one of the phase leads in the motor seems to be open circuit to the center wye point, so that tells me one of the windings probably burned up.

I logically want to say that whatever is internally causing the motor to be seized is the root cause, and then that made the winding burn up. But, is it reasonable that it was the other way around? Could there have been some type of external OL from the connected machine onto the motor, then the winding heated/failed/burned, and then that melting action “glued” some parts together internal to the motor that’s causing it to be seized? I was thinking it would have to be pretty catastrophic heating of the stator to melt something with the rotor that would cause it to be stuck, but maybe not?



Side note: the OL dial was set way too high, so it had no chance of opening first.

 

[ActionDave]

Seized bearing I bet.

 

[Hv&Lv]

Bearings seized, causing the motor to drag (overload) causing the winding to burn.
A picture of the windings inside would be great.

Ol Dave beat me to it…

 

[ActionDave]

And I didn't even have to get up early to do it.

 

[Eddie702]

2hp take it apart and find out

 

[ptonsparky]

Not worth the effort. Replace. Set the overload correctly. Make sure the motor is big enough for the load of someone turned them up to high.

 

[bwat]

I couple more details to add.

This is first time working with this client so I’m taking all history info with a grain of salt.

Supposedly this isn’t the first time this motor has needed replaced within the last year or so.

I may not have opportunity to open it up and look because client is in discussion with the OEM due to warranty and possibly sending the motor to them to evaluate.

I’m good on the troubleshooting and getting it resolved. My question wasn’t “what should I do?” but was on more of the theoretical “is it possible that the winding opened up first and somehow triggered something that locked the rotor”. Is that even a reasonable thought? My best guess was bearing as well and it seems like that’s the consensus here also, but what’s the chance of them having bearing failures on the original and replacement motor in short time frame..

I will say though that I’ve had an odd number of bearing failures in the past 2 or 3 years for whatever reason m. No VFD on this motor btw (mentioning for pitting concerns).

 

[petersonra]

Put a run-out gauge on the motor shaft and make sure it's lined up properly. Does not take a lot of run out to ruin bearings.

 

[ptonsparky]

Belts can be too tight resulting in overload and bearing wear.

 

[Little Bill]

Assuming this is 3ph, if one leg was lost, that would definitely damage the motor.
@bwat
Did anyone check for an open leg?

 

[ActionDave]

...I’m good on the troubleshooting and getting it resolved. My question wasn’t “what should I do?” but was on more of the theoretical “is it possible that the winding opened up first and somehow triggered something that locked the rotor”. Is that even a reasonable thought? My best guess was bearing as well and it seems like that’s the consensus here also, but what’s the chance of them having bearing failures on the original and replacement motor in short time frame..

I will say though that I’ve had an odd number of bearing failures in the past 2 or 3 years for whatever reason m. No VFD on this motor btw (mentioning for pitting concerns).

It is in the realm of possibility that a winding could have burnt up and spit out enough metallic or carbon deposits to cause the motor to "drag iron".

 

[Frank DuVal]

It is in the realm of possibility that a winding could have burnt up and spit out enough metallic or carbon deposits to cause the motor to "drag iron".

Carbon (graphite) is a lubricant. Copper, sure, but unlikely. The shaft probably needed to be stopped before the molten copper poured over the armature.

 

[kwired]

I couple more details to add.

This is first time working with this client so I’m taking all history info with a grain of salt.

Supposedly this isn’t the first time this motor has needed replaced within the last year or so.

I may not have opportunity to open it up and look because client is in discussion with the OEM due to warranty and possibly sending the motor to them to evaluate.

I’m good on the troubleshooting and getting it resolved. My question wasn’t “what should I do?” but was on more of the theoretical “is it possible that the winding opened up first and somehow triggered something that locked the rotor”. Is that even a reasonable thought? My best guess was bearing as well and it seems like that’s the consensus here also, but what’s the chance of them having bearing failures on the original and replacement motor in short time frame..

I will say though that I’ve had an odd number of bearing failures in the past 2 or 3 years for whatever reason m. No VFD on this motor btw (mentioning for pitting concerns).

pretty doubtful that winding failure led to bearing failure.

as mentioned too much belt tension can be hard on bearings, not only the motor itself but on the driven load.

Items that are outdoors but maybe aren't used all that often or only used "seasonally", can tend to have internal condensation issues or even rain water gets directly in a failed seal or something and if that ultimately gets into bearings can rust them or even completely seize them up.

Many totally enclosed motors often still have drain holes for condensation to drain, but if not mounted with base down, you might need to rotate the end housings so that the drain hole is located on bottom of the application. If drain hole is on top and it is outdoors or in wash down area not only can't it drain, but the improperly located holes will let water in easily.