The protection of the motor by the power converter mainly includes the following aspects: overvoltage protection, undervoltage protection, overcurrent protection, phase loss protection, inverter protection, overload protection, grounding protection, short circuit protection, overfrequency protection and stall protection.
1. Overvoltage protection
The output of the inverter has a voltage detection function, and the inverter can automatically adjust the output voltage so that the motor cannot withstand overvoltage. Even if the output voltage adjustment fails, and the output voltage exceeds 110% of the normal voltage, the inverter will protect the motor by stopping.
2. Under-voltage protection
When the motor voltage is lower than 90% of the normal voltage, the inverter protection stops.
3. Overcurrent protection
When the current of the motor exceeds 150%/3 seconds of the rated value or 200%/10 microseconds of the rated current, the inverter stops working to protect the motor.
4. Lack of phase protection
Monitor the output voltage. When the output is out of phase, the inverter will sound an alarm. After some time, the inverter will stop to protect the motor.
5. Inverted phase protection
The inverter can only rotate in one direction, and the direction of rotation cannot be set. Unless the user changes the phase sequence of the motor A, B, and C wiring, there is no possibility of inverting the phase.
6. Prevent overload
The inverter monitors the motor current. When the motor current exceeds 120%/1 minute of the rated current, the inverter stops working to protect the motor.
7. Grounding protection
The inverter is equipped with a special grounding protection circuit, which is generally composed of a grounding protection transformer and a relay. When one or two phases are grounded, the inverter will give an alarm. Of course, we can also design it to protect the shutdown immediately after grounding if the user requests.
8. Short circuit protection
After the output of the inverter is short-circuited, it will inevitably cause overcurrent. The inverter will stop the motor in 10 microseconds.
9. Over-frequency protection
The inverter has the function of large and small frequency limiting, so that the output frequency can only be within the specified range, so as to achieve overclocking protection function.
10. Stall protection
Stall protection is typically used in synchronous motors. For asynchronous motors, the stall during acceleration is necessarily overcurrent, and the inverter achieves this protection function through overcurrent and overload protection. Stall during deceleration can be avoided by setting a safe deceleration time during commissioning.
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