As with any electrical equipment, the key to prolonging the life and quality performance of an electric motor is regular preventive maintenance. Things to observe when conducting your maintenance check include:
- Conducting periodic maintenance examination
Most troubles could be easily avoided with periodic examinations and maintenance checks; then you will easily catch instances of corrosion, loose wiring, and poor electrical contact. These matters should be dealt with immediately before they become more severe.
Aside from visual examinations, you can detect trouble in an electric motor by feeling for unusually high temperatures and listening for unusual sounds. These may signal possible bearing issues.
Check that there is appropriate belt tension. Couplings should be tight, and sheaves should be seated firmly. Alignment checks should also be conducted for motor-generator sets and motor-load couplings. Voltage and current checks should also be conducted.
It would be helpful to keep records of the results of your periodic maintenance checks, as the results over time will indicate the condition of the motor.
- Proper Lubrication
Oil and grease are commonly used for the lubrication of electric motors. Lubrication is necessary because it maintains the performance of, and prolongs the life of, a bearing. Bearings should be lubricated consistently and properly and must neither be under-greased nor over-greased. Typically, manufacturers provide a motor in which the bearings are per-greased, so keep this in mind. An over-greased electric motor can slow down heat dissipation and may cause tolerance to stack up, thus causing or increasing any defects in the bearing. Bear in mind, though, that not all bearings should be lubricated, such as sealed bearings, which can only be lubricated when they are dismantled. Always consult the specs of your equipment to be sure.
- Bearing Inspection
The most common cause of trouble in electric motors is bearing failure. This can result from improper lubrication, either under-greasing or over-greasing; misalignment; using the wrong bearing type; and harsh environments.
Bearings need to be changed at recommended intervals.
- Shield the motor from extreme vibrations
Motors should not be exposed to extreme vibrations, even when they are idle. The reason is that the vibrations can cause the bearings to vibrate and rub away their grease. Extreme vibrations may also cause excessive friction between the bearings and other metal surfaces, which is not recommended.
Excessive vibration is detected by a vibration-analysis test. This can be caused by electrical problems, but more often than not, the cause is mechanical, such as misalignment, improper balance, excessive belt tension, or the improper balance of a rotating member.
- Clean the motor periodically
Regular cleaning is a basic principle of all maintenance checks, and that includes electric motors. The intake and outlet openings, the channels between the cooling fans, should be regularly cleaned, and dirt and debris removed. Otherwise, dirt and debris buildup can cause overheating, and the motor could fail prematurely.
There are some that use compressed air to clean away the dust and dirt in the interior of a motor, but some do not recommend this as it can push contaminants deeper into the windings. If you are using compressed air, however, make sure that you are not using more than 50 lbs. As an alternative, cleaning can be done with the use of a long-handled dog leg brush, or a vacuum.
Also, make sure that the motor is kept dry. Excessive moisture can cause rust and other issues, which may build up in electric motors if they remain unused for some time. Protect the motor from moisture by using grease.
Make sure that motors are kept clean. Dirt and dust can cause an increase in temperature, but higher temperatures may also be caused by restricted ventilation. Watch out for dirt, dust, oil, grass, and other objects, and keep them from clogging the ventilation passages of open-frame motors.
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