During the production process, motors are often damaged due to improper operation, which not only results in financial losses but also has a significant impact on production progress. Therefore, the correct use of frequency converters has a positive effect on protecting motors. Our company has summarized the protection of motors by frequency converters in the application of motor frequency conversion as follows:
overvoltage protection
The output of the frequency converter has a voltage detection function, and the frequency converter can automatically adjust the output voltage to prevent the motor from withstanding overvoltage. Even when the output voltage adjustment fails and the output voltage exceeds 110% of the normal voltage, the frequency converter will still protect the motor by shutting down.
Undervoltage protection
When the voltage of the motor is lower than 90% of the normal voltage, the frequency converter protection stops.
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 frequency converter protects the motor by shutting down.
phase loss protection
Monitor the output voltage. When there is a phase loss in the output, the frequency converter will sound an alarm. After a period of time, the frequency converter will stop to protect the motor.
Reverse phase protection
The frequency converter allows the motor to only rotate in one direction and cannot set the rotation direction. Unless the user changes the phase sequence of the wiring of motors A, B, and C, there is no possibility of reverse phase.
overload protection
The frequency converter monitors the motor current. When the motor current exceeds 120% of the rated current for 1 minute, the frequency converter stops to protect the motor.
grounding protection
The frequency converter is equipped with a dedicated grounding protection circuit, which is generally composed of grounding protection transformers and relays. When one or two phases are grounded, the frequency converter will sound an alarm. Of course, if requested by the user, we can also design to immediately protect the shutdown after grounding.
short circuit protection
After the output of the frequency converter is short circuited, it will inevitably cause overcurrent. Within 10 microseconds, the frequency converter will stop to protect the motor.
Overfrequency protection
The frequency converter has maximum and minimum frequency limitation functions, which limit the output frequency to a specified range, thereby achieving overclocking protection function.
Stall protection
Stall protection is generally applied to synchronous motors. For asynchronous motors, stall during acceleration is inevitably manifested as overcurrent, and the frequency converter achieves this protection function through overcurrent and overload protection. Stalling during deceleration can be avoided by setting a safe deceleration time during the debugging process.