Electrical reliability is a very important functional requirement of three-phase asynchronous motor products, which is mainly realized by controlling the temperature rise level of the motor. Therefore, the winding temperature rise of three-phase asynchronous motor is the key index to consider the quality of motor products, such as low-voltage motor and high-voltage motor. In order to ensure that the three-phase asynchronous motor does not heat, in addition to leaving enough margin in the design, it is necessary to discuss or imitate the manufacturing process and specific working conditions of the three-phase asynchronous motor. In the process of winding production and processing, poor welding will lead to the rise of winding temperature and winding resistance; When three-phase asynchronous motor works, the damage of anti corona layer of winding will lead to corona discharge; Excessive vibration of the motor will damage the insulation layer of the winding; The entry of conductive foreign matter into the winding and the actual harsh environmental conditions may cause damage to the motor winding. All these components which directly cause fatal damage to the conductive winding will make the motor work normally. When the winding temperature exceeds the allowable value of insulation, the bonding ability and mechanical strength of insulation will be reduced, which will make the insulation flow sticky, aging, delamination, loosening and shelling, accelerate the thermal corrosion of insulation and shorten the service life of coil.
In the three-phase asynchronous motor maintenance workshop, we found that the dust on the outer surface of many motor windings is very serious, many of them are charged dust, many users simply ignore this point. The general understanding of motor temperature rise, temperature rise means that the temperature of electrical and electronic equipment components is higher than the ambient temperature. With the passage of time, the temperature of the outer surface of the conductor continues to rise until it is stable. The stable judgment condition is that the temperature difference between the front and back of all inspection points should not exceed 2K within an hour inspection interval. At this time, the difference between the temperature measured at any detection point and the uniform ambient temperature 1 / 4 after the detection cycle is called temperature rise, and its unit is K. In order to verify the service life, stability and other characteristics of electronic products, the temperature rise of important components (such as the windings of motor products) is usually checked. The tested equipment works at a specific temperature higher than its rated working temperature. After stabilization, the temperature of its components is recorded to rise above the ambient temperature to verify whether the product planning is reasonable.
In electrical products, the rated temperature rise of three-phase asynchronous motor refers to the large allowable temperature rise of motor winding under the planned ambient temperature, which depends on the insulation grade of winding. The temperature rise depends on the heating and heat dissipation of the motor during operation. Usually according to the temperature rise to determine whether the motor cooling is normal.
The temperature of three-phase asynchronous motor refers to the practical heating temperature of each part of the motor, which has a great influence on the insulation material of the motor. Too high temperature will make the insulation aging, shorten the life of the motor, and even lead to insulation damage. In order to avoid insulation aging and damage, the temperature of motor winding and other parts is restricted, which is the allowable temperature of motor.
The temperature rise of three-phase asynchronous motor will change under different environmental conditions. When the environmental conditions are bad, such as plateau environment and closed environment, the temperature rise of the motor will increase. Therefore, the motor under different working conditions should be adjusted according to the practical situation.
