SERVICE
When the motor is difficult to start, or when it drives its rated load, does the motor speed drop significantly below its rated speed?
The power supply voltage may be too low; measure the supply voltage immediately and address the issue.
Alternatively, the motor may have been incorrectly selected—trying to drive a heavy load with an undersized motor—which can make it difficult to handle the current load. In such cases, consider choosing a motor with appropriate power rating.
If abnormal vibration and noise are accompanied by high current, it may indicate a phase loss in the power supply, an open circuit in one phase, or a single-phase open or short circuit in the motor. Immediately disconnect the power and stop the machine; inspect the power supply and the wiring in the junction box, or disassemble the motor to examine the winding condition.
