Ch 18

Motor failure commonly occurs due to overheating, improper power supply, improper application, improper maintenance, and motor damage.

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Single phasing is the minimum condition of voltage unbalance.

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A troubleshooter can observe the burning and opening of the first few turns of windings, which occur when a motor has failed due to a voltage surge.

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Any motor that is not operated on regular basis should contain a heating element to keep the motor dry.

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Common causes of motor overcycling from improper maintenance include misalignment, vibration, and improper belt tension.

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If the motor and driven load are misaligned, premature failure of the motor bearings, load, or both may occur.

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The final step of any troubleshooting procedure is to identify the symptoms of motor failure.

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Most problems with three-phase motors involve the centrifugal switch, thermal switch, or capacitor.

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Caution should be taken with any motor that has an automatic reset, as the motor can automatically restart at anytime.

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Poor starting torque in a capacitor motor may prevent the motor from starting, which will usually trip the overloads.

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