Quick steps to debug the inverter – Xinjie

1. Check the full-load power supply of the inverter (Variable-frequency Drive (VFD).

1. Ground the terminal strip of the VFD.

2. Type the switching power supply of VFD into the terminal and receive it from the switching power supply through the power switch of the leakage protector.

3. Check whether the original flash information of the VFD flashing information window is all normal, assuming that there is a mistake, it should be calibrated, otherwise it will be returned.

4. Understand the practical operation keys of VFD. Generally, VFD has six keys, such as RUN, STOP, PROG, data message p, UP, ▲, DOWN, ", etc. At the same time, in practice, the key boundaries of different VFDs are the same. In addition, some VFDs have utility buttons such as monitor flashing, reset, jogging, and shifting.

Quick steps to debug the inverter – Xinjie

Quick steps to debug the inverter – Xinjie

2. VFD with motor works at full load

1. Set the output power of the motor, which is very small, and think about the amount of current in the VFD operation inductively.

2. Set the VFD's maximum output frequency, fundamental frequency, and torque characteristics. General-purpose VFDs always have several VPf curves for customers to choose, and customers should select the appropriate VPf curves according to the characteristics of the load when applying. Assuming that the load of centrifugal fans and pumps is assumed, the torque working code of the VFD should be set to the variable torque and reduced torque working characteristics. In order to better improve the low-speed gear characteristics of VFD starting, so that the torque output by the motor can be used to consider the rules for consumer production load starting, the starting torque must be dispatched. In the multi-threaded motor DC frequency conversion system software, the control of torque is more complicated. At low frequencies, the damage caused by resistors and reactance cannot be ignored, but if VPf is kept as a parameter, the magnetic flux is reduced, and the output torque of the motor is reduced. Therefore, in the low frequency band, it is necessary to turn on the operating voltage to properly compensate for the torque improvement. Generally, VFD is set up by the customer's manpower.

3. Set VFD as the built-in computer keyboard to practice operation, press the work button and stop button to check whether the motor can start and stop normally.

4. Understand the protection code when common defects occur in VFD work, observe the original value of thermal protection car relay, observe the setting value of overvoltage protection, and change it if necessary. VFD application staff can turn on the settings of the VFD's electronic thermal relay effects according to the VFD's operating manual. When the output current of the VFD exceeds its promised current, the VFD's overcurrent protection will disconnect the output of the VFD. Therefore, the maximum threshold value of the thermal relay of the VFD electronic device does not exceed the maximum promised output current of the VFD.

Third, load test work

1. Manually operate the working stop button of the VFD control panel, observe the whole process of motor working stop and the flashing information window of VFD to see if there is any abnormal situation.

2. Assuming that the VFD has an overcurrent protection attitude during the whole process of starting P to stop the motor, the acceleration P deceleration time should be set again. The instantaneous speed of the motor in addition and gear change lies in the acceleration torque, and the frequency elasticity coefficient of VFD in the whole process of starting and braking system is set by the customer. Assuming that the inertia torque or load of the motor changes, and the speed increase or shift is stopped according to the preset frequency elasticity coefficient, there may be a lack of acceleration torque, which may cause the motor to flutter, that is, the motor speed ratio is not in harmony with the VFD output frequency, resulting in overcurrent or overvoltage. Therefore, it is necessary to effectively set the acceleration and deceleration times according to the motor moment of inertia and load, so that the frequency elasticity coefficient of VFD can be harmonious with the elastic coefficient of the motor speed ratio.

The way to check whether the setting is effective is to select the acceleration and deceleration time according to the work experience to open the setting, if there is an overcurrent during the whole process of starting, the acceleration time can be moderately increased; If there is an overcurrent during the whole process of the braking system, the deceleration time is moderately increased. On the other hand, the acceleration and deceleration time should not be set too long, and the time will damage the consumption rate, especially when the system is always started and braked.

3. Assuming that the VFD is still protected within the limited time, the working curve diagram of the start and stop should be changed from parallel line to S-shaped, and the U-shaped line should be S-shaped and inverse U-shaped. When the inertia force of the motor load is very large, a longer starting stop time should be selected, and the type of working curve should be set according to its load characteristics.

4. Assuming that VFD still has common shortcomings in work, we should try to increase the protection value of a larger current, but the protection cannot be canceled, and at least 10%-20% of the protection capacity should be reserved.

5. Assuming that the common shortcomings of VFD work still occur, the VFD with a larger output power should be replaced

6. Assuming that the VFD propulsion motor cannot reach the preset rate during the whole starting process, it is likely that there are two situations:

(1) The system software produces dynamic electrical engineering resonance, which can be distinguished from the sound of motor work.

By choosing the method of setting the frequency bounce value, it is possible to bypass the resonance point. Generally, VFDs can set three levels of bounce points. When VPf dominates the VFD driver multi-threaded motor, in some frequency bands, the current and speed ratio of the motor will vibrate, and the system software will not work when it is severe, and even in the whole process of acceleration, the current protection will promote the motor to not be able to start normally, and the motor load or moment of inertia will be more severe than the hour. Generally, VFDs always have a frequency jumping effect, and customers can set the jump point and the total width of the jump on the VPf curve graph according to the frequency point of vibration generated by the system software. When the motor accelerates, it can actively cross this frequency band to ensure that everything can work properly.

(2) The torque output ability of the motor is lacking, the original basic parameters of VFD of different well-known brands are not the same, and the load ability is not the same under the same standard, and it is also very likely that the load ability of the motor is not the same due to the different VFD control measures; Or due to the different output efficiency of the system software, there will be a certain difference in the load ability. In such cases, it is possible to increase the value of torque progression. Assuming that it cannot be reached, the effect can be improved by manual torque, and the temperature rise of the motor will increase without setting it too large. The assumption is still not good, and it should be changed to new control measures, such as the method of using a stable VPf ratio for Kobelco VFD, and the closed-loop control method for indoor space without a speed sensor when the starting is not up to the standard, which has a larger torque output ability. For centrifugal fans and pumps, the graph value of the torque drop should be reduced.

Quick steps to debug the inverter – Xinjie

Sections viewed

Contact

working hours