（1） After the timing is turned on, the motor cannot start, but there is a buzzing sound

Possible reasons:

(1) The power supply is not fully connected to single-phase starting;

(2) Motor overload;

(3) Being stuck by dragging machinery;

(4) The rotor circuit of the wound motor is open and disconnected;

(5) The head end position inside the stator is connected incorrectly, or there is a broken wire or short circuit.

Solution: (1) Check the power cord, motor lead out, fuse, and switch contacts, identify the open circuit position, and eliminate it; (2) Unload and start with no load or half load; (3) Check the dragged machinery and troubleshoot it; (4) Check the connection of the electric brush, slip ring, and starting resistor of each contactor; (5) Re evaluate the ends of the three phases and check if there are any visible wires or short circuits in the three-phase windings.

（2） The motor has difficulty starting and the speed is low after adding the rated load.

Possible reasons:

(1) The power supply voltage is low;

(2) Originally, the corner connection was mistakenly connected to a star connection;

(3) The cage bar end of the squirrel cage rotor is welded off, loose or broken.

Solution: (1) Increase the voltage; (2) Check the wiring method of the nameplate and correct the wiring method of the stator winding; (3) After examination and targeted treatment.

（3） After the motor starts, it heats up beyond the temperature rise standard or emits smoke

Possible reasons:

(1) The power supply voltage is too low, causing excessive temperature rise of the motor under rated load;

(2) Poor ventilation of the electric motor or high environmental humidity;

(3) Motor overload or single-phase operation;

(4) Frequent starting or excessive forward and reverse rotation of the electric motor;

(5) The stator and rotor rub against each other.

Solution: (1) Measure the no-load and load voltages; (2) Check the motor fan and clean the ventilation duct, strengthen ventilation and reduce ambient temperature; (3) After checking the current of each phase with a clamp type ammeter, treat it accordingly; (4) Reduce the number of forward and reverse rotations of the motor, or replace it with a motor suitable for frequent starting and forward and reverse rotation; (5) Treatment of aunt's symptoms after examination.

（4） Low insulation resistance

Possible reasons:

(1) The winding becomes damp or water drips into the interior of the motor;

(2) Dust and oil stains on the winding;

(3) The insulation of the stator winding is aging.

Solution: (1) Heat and dry the stator and rotor windings; (2) Wipe the end of the winding with gasoline and dry it; (3) Check and restore the insulation of the outgoing line or replace the insulation wire board of the junction box; (4) Generally, it is necessary to replace all windings.

（5） Electric motor casing is electrified:

Possible reasons:

(1) Insulation or junction box insulation wire board for motor lead wires;

(2) The end of the winding touches the casing;

(3) The motor casing is not reliably grounded

Solution: (1) Restore the insulation of the motor lead or replace the insulation board of the junction box; (2) If the grounding phenomenon disappears after removing the end cap, insulation can be added to the winding end before installing the end cap; (3) Ensure reliable grounding of the motor casing according to the grounding requirements.

（6） Abnormal sound during motor operation

Possible reasons:

(1) Wrong connection of stator winding, local short circuit or grounding, causing three-phase current imbalance and noise;

(2) There are foreign objects or severe lack of lubricating oil inside the bearing.

Solution: (1) Check separately and prescribe the right medicine; (2) After cleaning the bearings, replace the lubricating oil with 1/2-1/3 of the bearing chamber.

（7） Motor vibration

Possible reasons:

(1) The installation foundation of the electric motor is uneven;

(2) The rotor of the electric motor is unbalanced;

(3) Unbalanced pulley or coupling;

(4) Bending of the shaft head or eccentricity of the pulley;

(5) The electric motor fan is unbalanced.

Solution: (1) Flatten the motor base and fix it firmly after finding a level; (2) Static or dynamic balancing of rotor calibration; (3) Perform belt pulley or coupling balancing; (4) Straighten the shaft, align the pulley, and then insert the heavy-duty vehicle; (5) Calm down the fan.

Attention: When disassembling and maintaining explosion-proof fans, do not damage the explosion-proof surface. Before opening the cover of the explosion-proof axial fan for maintenance, the front power supply must be disconnected.