Common fault inspections of AC electric motors

1. Listen to the sound and carefully look for the fault point. When the AC asynchronous motor is running, if you find a thin "buzzing" sound without any changes in high and low, it is a normal sound. If the sound is rough and sharp, "Buzzing" and "hissing" sounds are precursors of failure, and the following reasons should be considered:
(1) The iron core is loose. The vibration of the motor during operation and the temperature changes from high to low will deform the iron core fixing bolts, causing the silicon steel sheets to loosen, and generate large electromagnetic noise.
(2) Rotor noise. The sound produced by the rotation of the rotor is produced by the cooling fan. It is a "whining" sound. If there is a "dong-dong" sound like when beating a drum, it means that the motor suddenly starts, stops, or reverses the connection. In the case of braking and other speed changes, the acceleration torque causes the fit between the rotor core and the shaft to loosen. In mild cases, it can be continued to be used. In severe cases, it can be disassembled for inspection and repair.
(3) Bearing noise When the motor is running, you must pay attention to the changes in the bearing sound. Touch one end of the screwdriver to the bearing cover and the other end to your ear. You can hear the changes in the sound inside the motor. Different parts have different faults. , with different voices. A "squeaking" sound is caused by the irregular movement of the roller gun in the bearing, which is related to the clearance and grease condition of the bearing. The "sizzling" sound is the sound of metal friction, which is generally caused by the bearing being short of oil and grinding. The bearing should be disassembled and lubricated.
2. Use the sense of smell to analyze that the faulty motor has no peculiar smell during normal operation. If you smell any peculiar smell, it is a fault signal, such as a burnt smell, which is emitted by the insulator being grilled. As the temperature of the motor increases, in serious cases There will also be smoke; such as the smell of oil and coke, which is mostly due to the lack of oil in the bearing and the odor caused by the evaporation of oil vapor when it is close to dry grinding.
3. Use your hand to check the fault. Touch the casing of the TV with your hand to roughly judge the temperature. If the motor casing feels very hot when you touch it with your hand, and the temperature value is very high, you should check the cause, such as overload, excessive voltage. Wait, and then troubleshoot the cause.