How to protect the motor from the frequency converter
Frequency converter is widely used in various industries, mainly because of its energy saving and frequency conversion speed regulation function in the equipment and working condition system, so from what aspects does the frequency converter play a protective role on the motor Next, we will analyze and answer this question.
The protection of inverter to motor mainly includes the following aspects: over-voltage protection, under voltage protection, over-current protection, phase loss protection, phase inversion protection, overload protection, grounding protection, short-circuit protection, over frequency protection and stall protection. The following is a brief introduction to the protection methods of these inverter to the motor.
1. Overvoltage protection:
The output of the frequency converter has the function of voltage detection. The inverter can automatically adjust the output voltage, so that the motor does not bear the overvoltage. Even when the output voltage adjustment fails and the output voltage exceeds 110% of the normal voltage, the inverter can also protect the motor by stopping the machine.
2. Under voltage protection:
When the voltage of the motor is lower than 90% of the normal voltage, the inverter protection stops.
3. Over current protection:
When the current of the motor exceeds 150% / 3 seconds of the rated value, or 200% / 10 microseconds of the rated current, the frequency converter protects the motor by stopping the machine.
4. Open phase protection:
Monitor the output voltage. When the output phase is missing, the inverter will alarm. After a period of time, the inverter will stop to protect the motor.
5. Inverse protection:
The frequency converter makes the motor rotate only in one direction and cannot set the direction of rotation. Unless the user changes the phase sequence of motor a, B and C wiring, there is no possibility of reverse phase.
6. Overload protection:
The frequency converter monitors the motor current. When the motor current exceeds 120% / 1 minute of the rated current, the frequency converter protects the motor by stopping the machine.
7. Grounding protection:
Frequency converter is equipped with special grounding protection circuit, which is generally composed of grounding protection transformer and relay. When one phase or two-phase grounding occurs, frequency converter will alarm. Of course, if the user requires, we can also design for protection and shutdown immediately after grounding.
