Characteristics of Variable Frequency Motors
Customer Xiao Zhang is a purchaser from a factory and wants to buy a motor. He only knows that the motor speed is 1400 revolutions per minute, and with a frequency converter, it can reach 1600-1700. When buying a motor, he is frustrated and unsure whether to buy a regular motor or a variable frequency motor. Today, Wang Technology from Hengli Electric will take you to understand the characteristics of variable frequency motors:
Compared with ordinary motors, general-purpose variable frequency speed regulating motors have the following characteristics: variable frequency motors
1. Use a frequency converter for power supply.
2. Replace traditional motor fans with independent fans.
3. The insulation performance requirements for motor windings are higher than those for ordinary motors.
4. Due to the special nature of motor frequency conversion, motor resonance is prone to occur during the starting process of variable frequency speed regulation motors. Therefore, the rigidity of motor components and the overall structure should be fully considered to prevent vibration and noise problems in the motor.
The insulation level is generally selected as F level or higher, and the strength of ground insulation and inter turn insulation is strengthened to improve the ability of motor insulation to withstand impulse voltage.
The use of dedicated electromagnetic wires for variable frequency motors, especially for high-power motors, requires stricter requirements due to different application scenarios.
Requirements for forced ventilation and cooling. Compared with ordinary motors, the motor speed is not unique. If a built-in fan is used for cooling, the ventilation and heat dissipation effect of the motor will be greatly reduced; To achieve this, an independent ventilation and heat dissipation scheme should be adopted.
Generally, axial flow is used for strong ventilation near the fan; It should be noted that the fan cannot share power with the motor. The fan should be started before the motor starts, and the motor power should be turned off before stopping.
Axis current issue. For motors with a capacity exceeding 160KW, bearing insulation measures should be taken, such as insulated bearings, insulated bearing chambers, and adding discharge carbon brushes.
grease. For constant power variable frequency motors, when the speed reaches 2P motor speed, special high-temperature resistant lubricating grease should be used to prevent bearing grease loss due to temperature rise, which may cause bearing damage and winding burnout.
Manufacturing process control. The use of vacuum pressure coating manufacturing process and special insulation structure ensures the insulation withstand voltage and mechanical strength of the electrical winding.
The rotor dynamic balance control that improves the machining accuracy of components can operate at high speeds by selecting high-performance bearings.
