There is a close relationship between the temperature rise of the motor and the efficiency level, as follows:
Effect of efficiency on temperature rise
High efficiency is low temperature rise: motor efficiency refers to the ratio of output power to input power, high efficiency means that the motor has a strong ability to convert electrical energy into mechanical energy, and less energy is lost during operation. This lost energy is usually dissipated as heat, so efficient motors produce relatively little heat, resulting in a lower temperature rise. For example, a high-efficiency energy-saving motor, its internal winding resistance is small, the core loss is also low, and the energy converted into heat during operation is less, so the temperature rise of the motor is relatively small.
Low efficiency is high temperature rise: When the motor efficiency is low, it indicates that more electrical energy is not effectively converted into mechanical energy, but is converted into heat energy in various forms of loss, such as copper loss in the winding, iron loss in the iron core and mechanical friction loss. This extra heat raises the temperature of the motor, resulting in an increase in temperature rise. The temperature rise of the motor running in a state of high loss and high efficiency for a long time may exceed the allowable range, accelerate the aging of the motor insulation material, and shorten the service life of the motor.
Effect of temperature rise on efficiency
Moderate temperature rise has little effect on efficiency: within a certain temperature range, the efficiency of the motor is relatively stable, and the effect of temperature rise on efficiency is not obvious. This is because the material and structure of the motor have taken into account the temperature change during normal operation in the design, as long as the temperature rise is within a reasonable range, the performance parameters of the motor basically remain unchanged, and the efficiency can be maintained at a high level.
Excessive temperature rise leads to decreased efficiency: When the temperature rise exceeds a certain limit, it will have a negative impact on the efficiency of the motor. On the one hand, the increase in temperature will increase the resistance of the motor winding, according to Joule's law, the increase in resistance will lead to an increase in copper loss, thus reducing the efficiency of the motor. On the other hand, high temperature will make the magnetic properties of the motor core change, resulting in an increase in iron loss, but also affect the heat dissipation conditions inside the motor, further aggravate the loss, so that the efficiency is further reduced. In addition, too high temperature rise may also make the lubricating oil performance of the motor worse, increase the mechanical friction loss, and also lead to reduced efficiency.
In summary, the temperature rise of the motor interacts with the efficiency level. In practical applications, in order to ensure the efficient and reliable operation of the motor, it is necessary to take effective heat dissipation measures to control the temperature rise of the motor, and select efficient motor products to reduce energy loss and improve operation efficiency.
