Maintaining Electric Motors

Written by Bobby Fisher

Electric motors, like any other piece of machinery, is subject to wear, tear, and environmental hazards. As such, periodic maintenance will save you money by avoiding costly repairs. Moisture accumulation during rain and high humidity, low voltages, and wear due to lack of regular lubrication can all be sources of dysfunction in your electric motor. I’m here to provide you with tips on maintaining your electric motors.

Moisture in explosion-proof motors causes a lot of motor failures. The first step in preventing is making sure the motor is installed properly. This means installing it above grade. You never want the motor to be subject to standing water in low areas. The motor cannot, under any circumstances, be submerged under water.

The second step in preventing moisture is being aware of one of the more common ways that moisture buildup can occur. While operating, electric motors create a natural breathing process. All electric motors have air space inside of them. When they’re operating, the air inside the motor heats up and expands. This hotter air pushes out of the seals and escapes to the outside. When the motor is shut off the air inside cools off and shrinks and a vacuum develops inside the motor. This vacuum draws in air from the outside. If you’re constantly turning your motor off in damp, wet, and/or humid weather, the air that gets drawn in will condense and water will accumulate. Do this over and over and eventually there will be enough water inside the motor casing to short out the motor windings.

Luckily, this can be prevented. Once each week, when the weather is nice and dry, turn on your electric motors and leave them running for about an hour. This way, the motors heat back up, re-vaporize the moisture, and push it out. Then, when you shut off your motors, dry air will replace the moisture.

Low voltage conditions can also cause problems for electric motors. When a low voltage condition exists, electric motors can and will get hot and overheat. If your motor cannot develop enough speed to get off the starter winding or cannot pull its load then it will slow down. If you run electric motors for too long on low RPMs they will break down. You’ll have to replace your motor or have the winding rewound.

When your motor is being installed, take extra care to follow the wiring instructions on the motor’s dataplate. Check the voltage at the motor when the motor is running under a full load. Do this at the motor’s junction box only. If you notice a low voltage or suspect a low voltage, contact your power company.

The last tip I have is about lubrication. The bearings in electric motors need to be lubricated every 6 months. Motors in dusty or dry climates will need lubrication more often. However, you must be sure not to over lubricate the bearings. That would damage them. We’re aiming for a goldilocks amount of lubrication. Not too much, not too little. Once you’ve greased the bearings, let the motor run for 10 minutes. Before you replace the lubrication plug, allow any excess grease to expand and force its way out of the opening. This will ensure that the bearings were not over lubed. Use a high quality ball valve grease only. No other grease will do.

Anyone that follows these tips will have electric motors that run smoothly and efficiently.

Bobby Fisher

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