Motor is an indispensable device in our daily life, whether in home appliances, industrial production or transportation, are inseparable from its figure. However, the motor in the process of use, there will be occasional “buzzing but can not start” phenomenon, this problem often makes people confused. What exactly is the cause of the motor humming, but can not start it normally? Today we will unravel this mystery and explain the solution.

A. Causes of Motor Buzzing

A motor makes a certain sound during normal operation, which is due to the current passing through the motor's coils, creating a magnetic field and driving the rotor to rotate. However, when a motor hums but fails to start, it is usually due to one of the following reasons.

a) External factors

1. Power supply problem: Power supply is the basis for motor operation, and a stable power supply is required for motor startup. When the motor hums and fails to start, the first thing you need to check is whether the power supply is normal. Power supply problems may include unstable voltage, too low or too high voltage, unconnected or poor contact with the power cord, and so on. For example, if the power supply voltage is lower than the motor's rated voltage, the motor may not be able to get enough energy to start, resulting in a humming sound. In this case, it is necessary to check that the supply voltage is within the rated operating range of the motor and to ensure that the power cord is properly connected and not loose or broken.

2. Faulty starter and control circuits: The starter and control circuits of the motor are also a common cause of humming and failure to start. The starter may have failed due to damage to components such as thermal protectors, contactors, or incorrect wiring. Components such as relays, switches, and push buttons in the control circuit that are faulty may also prevent the motor from starting properly. In addition, if the motor lacks power to any of the phases (e.g., one of the three-phase motors is not connected), it can also cause the motor to fail to start and hum.

b) Internal Motor Causes

1. Stuck motor rotor: The rotor of the motor may be stuck and unable to rotate freely due to dust, debris or rust. When the motor is started, it will make a humming sound, but the motor will not start because the rotor cannot turn. This type of problem is common in motors that have not been maintained for a long time or have been overloaded.

2. Poor wiring or contact: If the motor's power supply wiring is in poor contact or has loose or broken wiring, the current will not be able to pass steadily into the motor. In this case, the motor may hum, but due to insufficient current supply, the motor will not start properly.

3. Overload protection: In order to protect the motor from damage caused by overload, many motors are equipped with overload protection devices. When the motor runs under high load for a long time it may cause overheating, which triggers the operation of the thermal protector, current protector and other protective devices. After these protective devices operate, the motor may hum but not start. In this case, it is necessary to wait until the motor has cooled down before attempting to start it, and to check whether the protective devices have operated incorrectly. Adjust or replace if necessary.

4. Excessive temperature: When the motor is overheated, it usually triggers the self-protection mechanism and stops automatically. If the motor temperature is too high, the motor protection system will cut off the power supply to prevent damage. At this point, the motor will hum, but because the power has been cut off, the motor will not start.

5. Bearing Problems: Worn or inadequately lubricated bearings inside the motor can increase friction between the parts, resulting in a buzzing sound. Worn bearings may also cause the motor to rotate with difficulty.

6. rotor problems: unbalanced, broken or other problems with the rotor can also cause the motor to vibrate and hum during operation. In addition, if the motor has too much stator-rotor clearance, air flow can also create noise.

7. Winding Failure: A motor with a shorted, broken or grounded coil may not run properly and hum. This type of failure usually requires inspection and repair by a service professional.

8. Mechanical jamming: Parts such as the motor shaft or pulleys that are jammed with debris can cause the motor to fail to rotate and emit a humming sound. At this point, the debris needs to be cleaned up to ensure that the motor runs smoothly.

Third, how to solve the motor humming but can not start the problem?

When the motor hums but can not start, we can take the following steps to troubleshoot and repair:

1. Check the power supply

First check whether the power supply of the motor is stable to ensure that the voltage and current are normal. If the power supply voltage is too low, you may need to use a voltage regulator to ensure the voltage is stable. If the power supply line is found to be faulty, the wire needs to be repaired or replaced in time.

2. Check the starting capacitor

For single-phase motors, check if the starting capacitor is working properly. If the capacitor is found to be aged or damaged, it needs to be replaced with a new capacitor of the same specifications. When replacing the capacitor, be sure to disconnect the power supply and connect the capacitor in the correct way.

3. Clean the motor

If the rotor of the motor is stuck due to dirt or foreign objects, try cleaning the motor. Always disconnect the power supply and then clean it to ensure that the rotor can spin freely. Keeping the motor clean will help it operate more efficiently and extend its life.

4. Check wiring connections

Check the motor's wire connections for looseness, breakage or aging. If problems are found, repair or replace the wires promptly.

5. Check overload protection

If the motor is equipped with an overload protection device, check whether it is triggered. If the overload protection has been activated, wait for the motor to cool down before trying to start, or manually reset the overload protection.

6. Seek professional maintenance

If the self-examination fails to solve the problem, it is recommended to contact professional maintenance personnel for inspection and repair, especially when the motor controller, starter and other components failures, it is best to be handled by professional and technical personnel.

Conclusion

The phenomenon that the motor hums but cannot start is usually caused by power supply problems, starting capacitor failure, rotor stall, poor line contact and other factors. Through timely inspection and repair, it can help the motor return to normal operation and avoid the inconvenience of equipment downtime. In daily use, regular maintenance and repair of the motor can effectively prevent the occurrence of such problems and extend the service life of the motor.