During the operation of various electromechanical equipment, it is common to encounter the phenomenon of motors buzzing but not rotating. This issue not only affects the normal operation of equipment, causing production interruptions, but in severe cases, it may also lead to motor burnout, resulting in economic losses. Understanding the underlying causes and taking targeted measures to solve them in a timely manner is crucial for ensuring the stable operation of the equipment. Next, let's delve into the reasons for the motor buzzing and not turning from multiple aspects such as power supply, motor itself, and load.
1、Malfunctions caused by power supply issues
（1）Insufficient voltage
The operation of the motor has strict requirements for the power supply voltage, which generally needs to be within ± 10% of the rated voltage. When the power supply voltage is lower than this standard, the starting torque of the motor will decrease significantly. Just like a motor with a rated voltage of 380V, if the actual voltage drops below 320V, the motor will not receive enough starting energy to generate sufficient electromagnetic torque to overcome rotor inertia, resulting in the inability to start and only producing a buzzing sound. This situation is particularly common during peak electricity consumption periods or when the power supply lines are too long or too thin in diameter.
（2）Phase deficient operation
For three-phase motors, the absence of one phase in the three-phase power supply will prevent the motor from forming a normal rotating magnetic field. The rotating magnetic field that was originally symmetrical in three phases has become a pulsating magnetic field due to phase loss, which cannot provide continuous rotational power for the motor. When the motor starts, it will make a strong buzzing sound and the speed cannot be increased. Long term phase loss operation can also cause the motor winding to overheat and burn out due to excessive current. The cause of phase loss may be the melting of fuses, poor contact of contactor contacts, or disconnection of power supply lines.
2、Abnormalities caused by motor malfunction
（1）Winding short circuit
The motor winding is the core component that generates electromagnetic induction. Due to long-term operation of the motor, the insulation layer of the winding may be damaged due to aging, moisture, overheating, and other reasons, resulting in a decrease in insulation performance between adjacent wires and causing short circuits. The resistance of the short-circuit part decreases, the current increases, and it disrupts the normal magnetic field distribution of the motor, making it unable to operate normally and emitting an abnormal buzzing sound. Severe winding short circuit can generate a large amount of heat, causing the motor to smoke and even trigger a fire.
（2）Bearing damage
As a key component supporting the rotor of a motor, bearings directly affect the rotational performance of the motor. Long term operation of the motor can cause damage to the ball or roller bearings and cracks in the inner and outer rings due to wear, poor lubrication, or excessive impact on the bearings. This not only causes sharp noise during motor operation, but also results in uneven air gap between the rotor and stator, causing friction and hindering motor rotation, resulting in buzzing sound.
（3）Broken rotor bar
The rotor of a squirrel cage asynchronous motor consists of guide bars and end rings. During the start-up and operation of the motor, the rotor bars will bear significant electromagnetic and mechanical stresses. When the motor is frequently started, overloaded, or subjected to severe vibration, the rotor bars may break. After the rotor bar breaks, the rotor current decreases, the electromagnetic torque decreases, the motor is difficult to start, the speed decreases during operation, and there is a buzzing sound.
3、The troubles caused by load issues
（1）Overloaded load
When selecting a motor, the appropriate power should be chosen based on the size and characteristics of the load. When the load driven by the motor exceeds its rated load, the required output torque of the motor increases, and the starting current also increases accordingly. If the load is too heavy, the starting torque of the motor cannot overcome the load resistance, and the motor cannot start normally, only making a buzzing sound. Even if the motor can be started, during operation, the speed will decrease due to overload, and the current will continue to be too high, ultimately causing the motor overheating protection to shut down.
（2）Load stuck
Load equipment may become stuck due to mechanical failure, foreign object blockage, and other reasons. When the motor drives a stuck load, it feels like it is locked and cannot rotate, while emitting a strong buzzing sound. In this case, the motor current will rise sharply, far exceeding the rated value, which may burn out the motor winding in a short period of time.
4、Other influencing factors
In addition to the main reasons mentioned above, the motor installation foundation is not firm, which can cause vibration and noise during operation, and in severe cases, it can affect the normal operation of the motor. In addition, foreign objects such as dust and debris entering the interior of the motor can also cause the motor to rotate obstructed and produce a buzzing sound. Excessive ambient temperature can affect motor heat dissipation, increase motor winding temperature, reduce motor performance, and even cause malfunctions.
When the motor buzzes and does not rotate, it is necessary to comprehensively investigate multiple issues such as the power supply, motor body, and load, accurately identify the fault point, and take effective measures to repair it. In daily use, it is also important to maintain and upkeep the motor by regularly checking the power supply voltage, motor windings, bearings, and other components to ensure stable and reliable operation of the motor.
Hengda Electric has always been dedicated to the research and development, production, and service of various types of motors. With advanced technology and equipment, lean manufacturing processes, reliable product quality, and satisfactory after-sales service, the company provides customers with the most suitable motor professional solutions and creates greater social value.
