1. After closing the switch, the motor does not rotate but only makes noise or cannot reach the normal speed. a) Check if there is a broken phase or incorrect wiring in the stator winding (delta connection mistakenly connected as star, one side of star connection reversed, etc.); b) Check if the fuse is blown or has poor contact; c) Check for cable ends, poor contact in one phase of the disconnecting switch or circuit breaker; d) Check if the motor or the driven machinery is stuck; e) If it is an internal fault of the motor, notify the maintenance personnel to handle it. 2. The motor fault protection device trips during startup: a) Check the primary winding of the motor and the driven machinery for signs of fault; b) Measure the motor insulation after power is cut off to check for grounding or broken wires; c) Notify the maintenance team to check the protection circuit; d) Contact the on-duty personnel of the user unit to reduce the load, close the water valve or air valve and start again. If the startup is unsuccessful, power should be cut off and the maintenance team should be notified for handling; 3. Sparks or smoke appear inside the motor during startup or operation. a) Contact the on-duty supervisor of the user unit to stop operation; b) Report to the shift leader to de-energize the motor and measure the motor insulation; c) Notify the maintenance team to check and handle. 4. Tripping immediately upon startup, without impact or vibration. a) De-energize and check the switch mechanism to ensure there are no loose connections or poor connections; b) Check the switch control power fuse and closing coil for any problems; c) Check the switch auxiliary contacts and wiring for any problems; d) If no obvious fault is found after the above checks, open the knife switch or pull the trolley switch to the test position to perform a trip test. If the test is successful, power can be restored and the motor can be started again. If the start is unsuccessful, notify the maintenance team to handle. 5. The sound of the running motor suddenly changes, and the ammeter reading rises or falls to zero. a) De-energize and check if there is a broken phase in the stator circuit; b) Contact the on-duty supervisor of the user unit to check for mechanical faults; c) Check if the system voltage is lower than the allowable value. 6. The stator current of the running motor oscillates periodically. a) Observe whether the mechanical load changes periodically; b) Check the rotor for damage after power outage; c) For wound-rotor motors, also check for faults such as poor contact in the slip ring short-circuit device or rheostat. 7. The motor is operating under overload and the temperature is too high. a) Contact the on-duty personnel of the user unit to reduce the load. If it cannot be reduced, add another motor; b) Improve ventilation by adding a fan for cooling or opening ventilation holes; c) Contact the on-duty personnel of the user unit to check for faults in the air cooler water system; d) If the above measures are ineffective, report to the superior to cut off the power and check for faults in the motor and its connected machinery. 8. The motor is vibrating violently. a) Contact the on-duty personnel of the user unit to immediately start the standby motor and stop the faulty motor; b) Check whether the anchor bolts at the motor base and foundation fixing points are tight; c) With the power off, contact maintenance personnel to disassemble the motor and mechanical coupling, and start the motor without load to see if the motor is faulty; d) Check the tightness of the end cover. If the bearing is externally mounted, the foundation fixing of the bearing housing should also be checked; e) If the motor is faulty and the cause cannot be found after the above checks, maintenance personnel should disassemble the motor, check whether the rotor is balanced, and check the condition of the bearings, etc.