Troubleshoot AC Motors – Part 1

This is a 4 part series, click to view each part: 1 : 2 : 3 : 4

A1: Check input power to starter. Is there power on all lines? (Three-phase motors won’t start on one-phase.)		Restore power on all lines

A2: Check starter. Is overload protection device opened?		Replace or reset device. Does it open again when starting?

A3: Is there power on all lines to motor?		Repair starter

A4: Is voltage to motor more than 10% below nameplate voltage?		Restore proper voltage.

A5: Check motor terminal connections. Are any loose or broken?		Repair connections.

A6: May be wrong motor for application. Is starting load too high?		Install Design C or Design D motor. Install larger motor.

A7: Is driven machine jammed or overloaded?		Remove jam or overload.

A8: Are misalignments, bad bearings or damaged components causing excessive friction in driven machine or power transmission system?		Repair or replace component.

A9: Are bad bearings, bent shaft, damaged end bells, rubbing fan or rotor or other problem causing excessive friction in the motor?		Repair or replace motor.

A10: Check stator. Are any coils open, shored or grounded?		Repair coil or replace motor.

A11: Check commutator. Are any bars or rings broken?		Replace rotor.

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