Frequency converters are widely used in various mechanical transmission fields. Due to the complexity of mechanical transmission, short-circuit faults of frequency converters often occur in practical applications. After some maintenance of short-circuit faults of frequency converters, they are summarized and classified as follows. I hope it can help everyone help.
1. Fault characteristics
1. The first trip may occur during operation, but if it is restarted after reset, it will often trip as soon as the speed is increased.
2. It has a large inrush current, but most inverters are already capable of protection tripping without damage. Because the protection trips very quickly, it is difficult to observe the magnitude of its current.
2. Judgment and treatment
1. The first choice is to judge whether there is a short circuit. In order to facilitate judgment, before restarting after reset, a voltmeter can be connected to the input side. When restarting, the potentiometer will rotate slowly from zero, and at the same time, pay attention to observe the voltmeter. If the output frequency of the inverter trips immediately as soon as it rises, and the pointer of the voltmeter returns to “0” momentarily, it means that the output terminal of the inverter has been short-circuited or grounded.
2. It is necessary to judge whether there is a short circuit inside the inverter or an external short circuit. At this time, you should disconnect the wiring of the inverter output terminal, and then turn the potentiometer to increase the frequency. If it still trips, it means that the inverter is short-circuited; The line from the inverter to the motor, and the motor itself.
3. Light-load over-current The load is very light, but the over-current trips.
This is a unique phenomenon of frequency conversion speed regulation. In the V/F control mode, there is a very prominent problem: the instability of the magnetic circuit system of the motor during operation. The basic reason is: when running at low frequency, in order to drive a heavy load, it is often necessary to perform torque compensation (that is, to increase the U/f ratio, also called torque boost). The degree of saturation of the magnetic circuit of the motor varies with the weight of the load. This kind of overcurrent trip caused by the saturation of the magnetic circuit of the motor mainly occurs under the condition of low frequency and light load. Solution: Adjust the U/f ratio repeatedly.
4. Heavy load overcurrent fault phenomenon. During the operation of some production machinery, the load suddenly increases, or even “stuck”.
Solution:
1 First of all, find out whether the machinery itself is faulty, and if so, repair the machine.
2 If this kind of overload is a phenomenon that may often occur in the production process, first consider whether the transmission ratio between the motor and the load can be increased? Appropriately increasing the transmission ratio can reduce the resistance torque on the motor shaft and avoid the situation that the belt does not move. If the transmission ratio cannot be increased, the only option is to increase the capacity of the motor and frequency converter.
5. Overcurrent during speed up or down. This is caused by too fast acceleration or deceleration, and the measures that can be taken are as follows:
- 1 Extend the speed up (down) time. First of all, find out whether it is allowed to extend the speed-up or speed-down time according to the requirements of the production process. If it is allowed, the time for speed-up (down) speed can be extended.
- 2 Accurately preset the function of self-handling (anti-stall) of speed up (down) speed. The frequency converter is equipped with a self-processing (anti-stall) function for the overcurrent in the process of speed up and down. When the raising (lowering) current exceeds the preset upper limit current, the raising (lowering) speed will be suspended, and the raising (lowering) speed will continue when the current drops below the set value.
The above is the full introduction of “Short-circuit faults in inverter maintenance and judgment and treatment methods”. I hope the content of this article can help you. If you want to know more relevant information, you can continue to pay attention to this website.
Frequency converters are widely used in various mechanical transmission fields. Due to the complexity of mechanical transmission, short-circuit faults of frequency converters often occur in practical applications. After some maintenance of short-circuit faults of frequency converters, they are summarized and classified as follows. I hope it can help everyone help.
1. Fault characteristics
1. The first trip may occur during operation, but if it is restarted after reset, it will often trip as soon as the speed is increased.
2. It has a large inrush current, but most inverters are already capable of protection tripping without damage. Because the protection trips very quickly, it is difficult to observe the magnitude of its current.
2. Judgment and treatment
1. The first choice is to judge whether there is a short circuit. In order to facilitate judgment, before restarting after reset, a voltmeter can be connected to the input side. When restarting, the potentiometer will rotate slowly from zero, and at the same time, pay attention to observe the voltmeter. If the output frequency of the inverter trips immediately as soon as it rises, and the pointer of the voltmeter returns to “0” momentarily, it means that the output terminal of the inverter has been short-circuited or grounded.
2. It is necessary to judge whether there is a short circuit inside the inverter or an external short circuit. At this time, you should disconnect the wiring of the inverter output terminal, and then turn the potentiometer to increase the frequency. If it still trips, it means that the inverter is short-circuited; The line from the inverter to the motor, and the motor itself.
3. Light-load over-current The load is very light, but the over-current trips.
This is a unique phenomenon of frequency conversion speed regulation. In the V/F control mode, there is a very prominent problem: the instability of the magnetic circuit system of the motor during operation. The basic reason is: when running at low frequency, in order to drive a heavy load, it is often necessary to perform torque compensation (that is, to increase the U/f ratio, also called torque boost). The degree of saturation of the magnetic circuit of the motor varies with the weight of the load. This kind of overcurrent trip caused by the saturation of the magnetic circuit of the motor mainly occurs under the condition of low frequency and light load. Solution: Adjust the U/f ratio repeatedly.
4. Heavy load overcurrent fault phenomenon. During the operation of some production machinery, the load suddenly increases, or even “stuck”.
Solution:
1 First of all, find out whether the machinery itself is faulty, and if so, repair the machine.
2 If this kind of overload is a phenomenon that may often occur in the production process, first consider whether the transmission ratio between the motor and the load can be increased? Appropriately increasing the transmission ratio can reduce the resistance torque on the motor shaft and avoid the situation that the belt does not move. If the transmission ratio cannot be increased, the only option is to increase the capacity of the motor and frequency converter.
5. Overcurrent during speed up or down. This is caused by too fast acceleration or deceleration, and the measures that can be taken are as follows:
- 1 Extend the speed up (down) time. First of all, find out whether it is allowed to extend the speed-up or speed-down time according to the requirements of the production process. If it is allowed, the time for speed-up (down) speed can be extended.
- 2 Accurately preset the function of self-handling (anti-stall) of speed up (down) speed. The frequency converter is equipped with a self-processing (anti-stall) function for the overcurrent in the process of speed up and down. When the raising (lowering) current exceeds the preset upper limit current, the raising (lowering) speed will be suspended, and the raising (lowering) speed will continue when the current drops below the set value.
The above is the full introduction of “Short-circuit faults in inverter maintenance and judgment and treatment methods”. I hope the content of this article can help you. If you want to know more relevant information, you can continue to pay attention to this website.
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