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I. No-load energization test of frequency converter
1.Ground the ground terminal of the frequency converter.
2.Will be the frequency converter power input terminal through the leakage protection switch to the power supply.
3.Check the frequency converter display window factory display is normal, if not correct, should be reset, or request for return.
4.Familiarize yourself with the operation keys of the frequency converter. General frequency converter are RUN, STOP, PROG, DATAPENTER, UP, ▲, DOWN, “ and so on 6 keys,different frequency converter operation key definition is basically the same.
In addition, some frequency converters have to MONITORPDISPLAY， RESET, JOG, SHIFT and other function keys.
II.Frequency converter with motor no-load operation
1. Set the power of the motor, the number of poles, to take into account the operating current of the frequency converter.
2. Set the maximum output frequency of the frequency converter, base frequency, set the torque characteristics. General frequency converter are equipped with a number of VPf curve for users to choose, the user should be used according to the nature of the load to choose the appropriate VPf curve.
If it is fan and pump loads, the torque operation code of frequency converter should be set to variable torque and reduced torque operation characteristics.
In order to improve the low-speed performance of the frequency converter at startup, so that the motor output torque can meet the requirements of the production load startup, to adjust the starting torque.
In the asynchronous motor frequency control system, the torque control is more complicated. In the low-frequency band, due to the resistance, leakage reactance of the impact can not be ignored, if you still keep VPf as a constant, the flux will be reduced, which reduces the output torque of the motor.
For this reason, in the low-frequency band should be appropriate compensation for voltage to enhance the torque. General frequency converter are manually set by the user to compensate.
3. Set the frequency converter to its own keyboard operation mode, press the run key, stop key, observe whether the motor can start and stop normally.
4. Familiarize yourself with the protection code when the frequency converter runs into trouble, observe the factory value of the thermal protection relay, observe the set value of the overload protection, and modify it when needed.
Frequency converter users can set the electronic thermal relay function of frequency converter according to the instruction manual of frequency converter.
When the output current of the frequency converter exceeds its allowable current, the over current protection of the frequency converter will cut off the output of the frequency converter.
Therefore, the maximum value of the threshold of the electronic thermal relay of the frequency converter does not exceed the maximum permissible output current of the frequency converter.
III. Test run with load
1. Manually operate the running stop key of the frequency converter panel, observe the motor running stop process and the display window of the frequency converter to see whether there is any abnormal phenomenon.
2. If start P stop motor process frequency converter over current protection action, should be reset acceleration P deceleration time. The acceleration of the motor in acceleration and deceleration depends on the acceleration torque, and the frequency change rate of the frequency converter in the process of starting and braking is set by the user.
If the motor inertia or motor load changes, according to the pre-set frequency rate of change of speed or deceleration, there may be insufficient accelerating torque, resulting in motor stall, that is, the motor speed and frequency converter output frequency is not coordinated, resulting in over current or over voltage.
Therefore, according to the motor rotational inertia and load reasonable setting acceleration and deceleration time, so that the frequency change rate of the frequency converter can be coordinated with the motor speed change rate.
Check whether this setting is reasonable method is first selected according to the experience of acceleration and deceleration time for setting, if in the start-up process of over current, it can be appropriate to extend the acceleration time; if in the braking process of over current, it is appropriate to extend the deceleration time.
On the other hand, acceleration and deceleration time should not be set too long, the time is too long will affect the production efficiency, especially when frequent start, brake.
3. If the frequency converter is still protected within a limited period of time, you should change the start P stop the operating curve from a straight line to S-shaped, U-shaped line or S-shaped, anti-U-shaped line.
Motor load inertia is large, you should use a longer start-stop time, and according to its load characteristics set the type of operating curve.
4. If the frequency converter still exists running fault, should try to increase the maximum current protection value, but can not cancel the protection, should leave at least 10% ~ 20% of the protection margin.
5. If the frequency converter running fault still occurs, should be replaced with a larger level of power frequency converter.
6. If the frequency converter driven motor in the start-up process can not reach the preset speed, there may be two cases: (1) the system has electromechanical resonance, can be judged from the sound of the motor running.
(1) The system electromechanical resonance, you can judge from the sound of the motor running.
Using the method of setting the frequency jump value, you can avoid the resonance point. General frequency converter can set three jump points.
VPf control frequency converter drive asynchronous motor, in some frequency bands, the motor current, speed will oscillate, when the system can not run, and even in the acceleration process of over current protection makes the motor can not start normally, in the motor light load or rotating inertia is more serious.
Ordinary frequency converter are equipped with frequency jump function, the user can according to the frequency point of system oscillation, in the VPf curve to set the jump point and jump width. When the motor acceleration can automatically skip these frequency bands, to ensure that the system can run normally.
(2) Motor torque output capacity is not enough, different brands of frequency converter factory parameters are set differently, under the same conditions, with load capacity is different, may also be due to different control methods of the frequency converter, resulting in different load capacity of the motor; or due to the different output efficiency of the system, resulting in differences in load capacity.
For this situation, you can increase the value of the torque increase. If you can not reach, available manual torque increase function, do not set too large, the motor temperature rise will increase.
If still can not, should be changed to a new control method, such as Hitachi frequency converter using VPf ratio constant method, start up can not meet the requirements, change to no speed sensor space vector control method, it has a greater torque output capacity. For fan and pump loads, the curve value of torque reduction should be reduced.
