Listen, see, touch, smell, and measure ", teaching you how to maintain three-phase asynchronous motors on a daily basis

A three-phase asynchronous motor, also known as an induction motor, is a motor with a simple structure, sturdy and durable, easy to use and maintain, and reliable operation. It is mainly composed of a stator and a rotor. At present, the vast majority of power equipment, such as machine tools, lifting equipment, transportation machinery, blowers, various pumps, as well as electric fans, medical equipment and other devices in daily life, are widely used. Three phase asynchronous motors need regular maintenance to ensure reliable operation.

hear

When the motor is running, its operating condition can be preliminarily determined by listening to its sound;

When the motor is working normally, if there is no significant change in load, the sound it emits will be uniform and free of noise;

A buzzing sound is emitted, and at the same time, a significant decrease in speed can be seen. If the current is measured and the current value increases, and the three phases are uneven or unstable, it may be due to major faults such as power phase loss, severe voltage unevenness in the three phases, or serious broken bars in the motor rotor;

The sound is loud and somewhat harsh, but relatively uniform, mainly due to excessive load or high power supply voltage. The load size can be determined by measuring the current;

When the sound is high or low, the reason is due to load fluctuations or power supply fluctuations;

There is noise, which can come from damaged bearings, friction between the fan and the fan cover or end cap, friction between the stator and rotor, or friction between the rotor and high insulation paper and slot wedges, foreign objects inside the motor, etc. It can be carefully detected and distinguished with the help of a screwdriver or other rod-shaped object.

see

Check whether the grounding protection of the motor is reliable, inspect the motor housing for cracks, and check whether the foundation screws and end cap bolts of the motor are loose;

Check the ventilation and environment of the motor, keep the motor and end cover clean and hygienic, ensure the normal operation of the cooling fan, ensure that the ventilation opening is normal, ensure that the external environment does not affect the normal operation of the motor, and the external environment temperature should not exceed 40 ℃;

Check if the working current of the motor exceeds the rated current (if there is an ammeter on site).

feel

Check for overheating of the electric motor;

Check for any abnormal vibrations in the electric motor;

When left for a long time by hand, it can be held for several tens of seconds at temperatures below 40 ℃, for about 10 seconds at temperatures between 40-45 ℃, and immediately retracted upon contact at temperatures around 50 ℃. There is a risk of burns at temperatures above 70 ℃.

smell

Check if the motor emits any abnormal odor;

Check whether there is a smell of volatile grease in the bearing area of the electric motor.

Analysis and Solutions for Abnormal Noise in Motor Bearings

Buzzing sound - a buzzing like sound produced by an electric motor when running without load. What kind of situation is generally caused by poor lubrication state, and replacing it with grease with good lubrication performance can solve it.

The sound of "sizzling" - the sound of metal friction. It is usually caused by dry grinding of bearings due to lack of oil, which can be eliminated by removing the bearings and adding lubricating grease.

The creaking sound is caused by the irregular movement of the rollers inside the bearing, which is related to the clearance of the bearing and the condition of the lubricating grease. When restarting different motors that have been idle for a long time, there will be this sound. If there is only this sound and no other abnormal phenomena, and the sound disappears immediately after adding lubricating grease, it is not a fault and the motor can still be used.

Jili Jili "sound is generated during the operation of rollers or ball bearings. If there are no other noises and the sound decreases or disappears significantly after adding lubricating grease, it is generally not a fault. The motor can still continue to operate, but close observation should be made to listen for any abnormalities in the sound.

In addition, when the motor bearings dry wear or experience serious malfunctions, the temperature near the bearings will increase and an oil burning smell may occur.