The feedback unit supplier reminds you that the task of motor protection is to ensure the long-term normal operation of the motor, avoid damage to electrical equipment, power grid, and mechanical equipment due to various faults, and ensure personal safety. The protection process is an essential component of all automatic control systems. This is about the protection of low-voltage circuits. Generally speaking, there are several commonly used protections, including short-circuit protection, overcurrent protection, fault protection, and undervoltage protection.
Install a reactor at the output end of the frequency converter:
This measure is most commonly used, but it should be noted that this method has some effect on shorter cables (below 30 meters), but sometimes the effect is not ideal.
Install dv/dt filter at the output of the frequency converter:
This measure is applicable to situations where the cable length is less than 300 meters, and the price is slightly higher than that of reactors, but the effect has been significantly improved.
Install a sine wave filter at the output of the frequency converter:
This measure is the most ideal. Because here, the PWM pulse voltage is converted into a sine wave voltage, which completely solves the problem of peak voltage when the motor operates under the same conditions as the power frequency voltage (no matter how long the cable is, there will be no peak voltage).
Install a spike voltage absorber at the interface between the cable and the motor:
The disadvantages of the previous measures are that when the power of the motor is high, the volume and weight of the reactor or filter are large, and the price is high. In addition, both the reactor and filter will cause a certain voltage drop, affecting the output torque of the motor. The use of a frequency converter peak voltage absorber can overcome these disadvantages. The SVA peak voltage absorber developed by Institute 706 of the Second Academy of China Aerospace Science and Industry Corporation adopts advanced power electronics technology and intelligent control technology, making it an ideal equipment for solving motor damage. In addition, the SVA peak absorber can also protect the bearings of the motor.