Motor Bearings Overheating at 60 Hz – Seeking Expert Advice

[Capetowners]

Motor & Pump Overheating Issue at 60 Hz – Need Insights

Motor Specs:

• 3-phase induction motor (440V, 60 Hz, 62A, 42 kW, 3555 RPM)

Issue:
Our pump runs fine at 50 Hz, but when switched to 60 Hz, the motor bearings overheat. The motor is coupled to the pump via a dummy shaft, and all bearings are new SKF units.


Questions:

1. Could the motor’s rated speed (3555 RPM) being close to synchronous speed (3600 RPM) be causing overheating?
2. What adjustments can mitigate this issue at 60 Hz?

Thanks y'all in advance

 

[TenPenny]

What flow/head is the pump running at? It looks like an OH5 style pump, so the motor bearings are carrying all the thrust loads of the pump. I'd say that the higher speed is overloading the motor bearings.

 

[Artisi]

Over greased?

 

[TugboatEng]

More important than over-greased, what is the base oil viscosity of your grease? Are you using a polyurea grease or a lithium grease?

SKF isn't calling for Kendall L-427 Super Blue grease are they? If so, that's definitely your problem.

Remember, high temp grease make bearings run hotter. If you want your bearings to run cooler use low temperature greases.

Why are you using split lock washers? They have no purpose other than to cause failures and increase inventory loads.

 

[LittleInch]

Is the pump designed for 60 htz operation? Power goes up by a factor of pump speed ^3. So this is 70% more power at 60 htz than 50 htz. Does that have an impact maybe?

 

[Capetowners]

What flow/head is the pump running at? It looks like an OH5 style pump, so the motor bearings are carrying all the thrust loads of the pump. I'd say that the higher speed is overloading the motor bearings.

at first time when the motor come in we thought it was normal service as we check all the parts which has to be repair or replace, and after that we take the motor for the run test and we run it at 50hz, and it did performs better. Then after we assemble the pump as well for test run and now we switch to 60hz which is supposed to run at this hertz but suddenly it fail by bearing getting seized, so after that we still trying to figured out what the problem is, as for now we tested in no load test but bearing and the shaft of the motor is getting overheat.

Yes is 0H5 type

@Artisi

 

[Ethnan]

Based on the motor spec- [3-phase induction motor (440V, 60 Hz, 62A, 42 kW, 3555 RPM)], at 50Hz, the motor speed would be 2,963RPM.
The RPM is higher at 60Hz. As already suggested by others, you may need to do any of the following:

1. Ensure bearings are properly lubricated with the recommended lubricant. Consider using better lubricant for the bearing, this may be more expensive though.
2. Ensure the rotor is properly balanced to minimize vibration which can cause overheating of bearing.

Good luck

 

[mfgenggear]

So what changed.?
Same exact type of bearing?
Lubricant properties?
When installing the bearing was manufacturing procedure?
What is the HP and Torque rating of the beating?
What is the RPM rating of the bearing.
Are all above identical as the original bearing.