bob
Titanium
- Joined
- Aug 12, 2002
- Location
- Regina, Canada
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Motor overheat question
- Thread starter bob
- Start date
- Replies 10
- Views 1,415
JohnEvans
Titanium
- Joined
- Sep 23, 2009
- Location
- Phoenix,AZ
Duhh I think so !! rub equals friction that equals HEAT !! You may also have a electrical issue but to start fix the rub.
rons
Diamond
- Joined
- Mar 5, 2009
- Location
- California, USA
I put a 5 hp 3 phase rotor on centers and trimmed it down slightly due to sloppy casting,
Thought I ruined the motor. But not after I statically balanced it.
Thought I ruined the motor. But not after I statically balanced it.
markz528
Hot Rolled
- Joined
- Sep 25, 2012
- Location
- Cincinnati
Yes.
Some years ago one of my customers reported that A phase was running hot on maybe a 500 hp motor. They had just worked on the RTDs, se we attributed it to bad RTD connections. It blew the winding a few weeks later. Found the drive end bearing inner race spun on the shaft and it acted as a bushing so we never picked it up on vibration. The rotor dropped and rubbed on the stator. Just happened that A phase was at the 6 o'clock position so that is why only A phase was running hot. Bottom line the rotor was rubbing for at least a couple weeks before it blew, but caused the motor to run hot.
Some years ago one of my customers reported that A phase was running hot on maybe a 500 hp motor. They had just worked on the RTDs, se we attributed it to bad RTD connections. It blew the winding a few weeks later. Found the drive end bearing inner race spun on the shaft and it acted as a bushing so we never picked it up on vibration. The rotor dropped and rubbed on the stator. Just happened that A phase was at the 6 o'clock position so that is why only A phase was running hot. Bottom line the rotor was rubbing for at least a couple weeks before it blew, but caused the motor to run hot.
bob
Titanium
- Joined
- Aug 12, 2002
- Location
- Regina, Canada
Thanks Mark pretty sure that's the problem. Going to try Ron's solution nothing much to loose.
Bob
Bob
johansen
Stainless
- Joined
- Aug 16, 2014
- Location
- silverdale wa
I would investigate why its rubbing before simply turning the rotor down.
Doubling the air gap to get the motor to work will decrease its power factor and if the windings are compromised by overheating, you need to derate the motor.
I suspect the phase that is closer to the rotor will run partially saturated and run at a higher voltage than the other 2 windings (due to the Y connection) so it will overheat the iron due to iron losses. This is not a problem on a 5hp or smaller motor, but its the reason i suspect markz reported a 500hp motor failing at the winding closest to the rotor. Once the rotor made contact, it would have been game over in minutes not weeks due to the laminations shorting the winding out in my opinion.
Doubling the air gap to get the motor to work will decrease its power factor and if the windings are compromised by overheating, you need to derate the motor.
I suspect the phase that is closer to the rotor will run partially saturated and run at a higher voltage than the other 2 windings (due to the Y connection) so it will overheat the iron due to iron losses. This is not a problem on a 5hp or smaller motor, but its the reason i suspect markz reported a 500hp motor failing at the winding closest to the rotor. Once the rotor made contact, it would have been game over in minutes not weeks due to the laminations shorting the winding out in my opinion.
bob
Titanium
- Joined
- Aug 12, 2002
- Location
- Regina, Canada
Cut .005 off armature runs fine now. Thanks to those that offered "Practical" ideas
Bob
Bob
Peter from Holland
Diamond
- Joined
- Jan 15, 2005
- Location
- The Netherlands
Some mustard after the meal
You could have rotated the shield 90-180 or 270 dgr and see if it runs free then
Peter
You could have rotated the shield 90-180 or 270 dgr and see if it runs free then
Peter
rons
Diamond
- Joined
- Mar 5, 2009
- Location
- California, USA
A couple of things.....
first, the rubbing looks like bearing shift or wear. Probably in the direction of belt pull, if it drives through a belt.
Second, the blackening is probably not "burning". Looks more like residue of the metal rubbed off of the rotor and stator.
Turning the rotor was not the right fix.
first, the rubbing looks like bearing shift or wear. Probably in the direction of belt pull, if it drives through a belt.
Second, the blackening is probably not "burning". Looks more like residue of the metal rubbed off of the rotor and stator.
Turning the rotor was not the right fix.
rons
Diamond
- Joined
- Mar 5, 2009
- Location
- California, USA
When I did mine it cleaned up the crusty aluminum castings on the ends. Then I statically balanced it. Quiet.
You should investigated why that rub happened. Where the long bolts holding the end bells not in a straight line.
Or is there a hole pattern on one cap that won't align with the opposite cap except in one position.
Because if you just put back everything and in that one spot you have a few thou of air gap. Won't that generate heat.
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