Product Manual

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AC Motor Trouble-Shooting Chart (cont’d)
Problem Likely Causes What To Do Bearings continuously fail. Load to motor may be excessive or unbalanced. Besides checking load, also inspect drive belt tension to ensure it’s not too tight may be too high. An unbalanced load will also cause the Bearings to fail. High ambient temperature. If the motor is used in a high ambient, a different type of bearing grease may be required. You may need to consult the factory or a bearing distributor. The motor, at start up, makes a loud Rotor may be striking stator. Ensure that motor was not damaged in shipment. Frame damage rubbing or grinding noise. may not be repairable. If you cannot see physical damage, inspect the motor’s rotor and stator for strike marks. If signs of rubbing are present, the motor should be replaced. Sometimes simply disassembling and reassembling motor eliminates rubbing. Endbells are also sometimes knocked out of alignment during transportation. Start capacitors continuously fail. The motor is not coming up to speed quickly enough. Motor may not be sized properly. Verify how long the motor takes to come up to speed. Most single phase capacitor start motors should come up to speed within three seconds. Otherwise the capacitors may fail. The motor is being cycled too frequently. Verify duty cycle. Capacitor manufactures recommend no more than 20, three-second starts per hour. Install capacitor with higher voltage rating, or add bleed resistor to the capacitor. Voltage to motor is too low. Verify that voltage to the motor is within 10% of the nameplate value. If the motor is rated 208-230V, the deviation must be calculated from 230V. Starting switch may be defective, preventing the Replace switch. motor from coming out of start winding. Run capacitor fail. Ambient temperature too high. Verify that ambient does not exceed motor’s nameplate value. Possible power surge to motor, caused by lightning If a common problem, install surge protector. strike or other high transient voltage.