From the analysis,the major cause for electric motor failure is a bearing defected around 75%.That why bearing lubrication very important to avoid electric motor breakdown.It also can save repairing cost for electric motor major failure.
Basic method for bearing lubrication.
1) Sleeve bearing motors
For this type,we must ensure the oil reservoir must be filled with oil to the correct level.If it used system self-lubricated bearings, the oil level will be at the center of the oil meter gauge.
2) Flood lubrication
For electric motor with flood lubrication, it have an inlet orifice to meter the oil flow to the bearing.If the supply pressure does not match that stated on the outline, the orifice size must be adjusted to produce the specified flow rate.To ensure optimum flow, the drain line should be vented to the atmosphere.
Oil inlet temperature:
- Normal below 50ºC
- Alarm 60ºC
- Trip 65ºC
3) For long term storage
If the motor is keep in storage for a long time (over three (3) months), We need to refilling of some new oil before operation to prevent bearing damage due to dry friction. The oil level should be kept at the center of the oil gauge.
4) Anti friction bearing
For motors that have been designed with anti-friction bearings,it must use with an oil mist lubrication system have been packed at the factory with a small amount of grease for short test running to check electric motor condition.For continuous running,it not be considered unless the oil mist system is installed.