Motor Control Troubleshooting Study Guide

Motor-control troubleshooting becomes easier when the power circuit and control circuit are treated separately and measurements are used to narrow the fault before parts are replaced.

Study contactors, overloads, coil voltage, start/stop logic, seal-in circuits, phase-loss symptoms, and the effect of mechanical load on motor current.

• Confirm whether the contactor pulls in, chatters, or remains de-energized.
• Compare all three line-to-line voltages on three-phase equipment.
• Measure control voltage at the contactor coil during the symptom.
• Treat overload operation as evidence rather than bypassing protection.
• Connect electrical measurements with the mechanical operating condition.