The supplier of frequency converter supporting equipment reminds you that the frequency converter is an electrical energy control device that uses the on-off function of power semiconductor devices to convert the power frequency power supply to another frequency. It can achieve soft starting, frequency conversion speed regulation, improve operating accuracy, change power factor, overcurrent/overvoltage/overload protection and other functions for AC asynchronous motors.
Mainly used in the application of fans and water pumps. In order to ensure the reliability of production, various production machinery are designed with a certain amount of surplus when equipped with power drives. When the motor cannot operate at full load, in addition to meeting the power drive requirements, the excess torque increases the consumption of active power, resulting in the waste of electrical energy. The traditional speed regulation method for equipment such as fans and pumps is to adjust the air and water supply volume by adjusting the opening of the inlet or outlet baffles and valves. The input power is high, and a large amount of energy is consumed in the interception process of the baffles and valves. When using variable frequency speed regulation, if the flow rate requirement is reduced, the requirement can be met by reducing the speed of the pump or fan. Below are the basic methods for debugging general frequency converters.
Basic methods and steps for debugging frequency converters:
1、 No load power on test of frequency converter
1. Ground the grounding terminal of the frequency converter.
2. Connect the power input terminal of the frequency converter to the power supply through a leakage protection switch.
3. Check if the factory display of the frequency converter display window is normal. If it is not correct, it should be reset. Otherwise, return or exchange is required.
4. Familiar with the operation keys of the frequency converter. A typical frequency converter has six keys: RUN, STOP, PROG, DATAPENTER, UP, ▲, and DOWN. The definitions of the operation keys for different frequency converters are basically the same. In addition, some frequency converters also have function keys such as MONITOR PLAY, RESET, JOG, and SHIFT.
2、 Variable frequency drive with motor running without load
1. When setting the power and number of poles of the motor, the working current of the frequency converter should be comprehensively considered.
2. Set the maximum output frequency, fundamental frequency, and torque characteristics of the frequency converter. Universal frequency converters are equipped with multiple VPf curves for users to choose from. Users should select the appropriate VPf curve based on the nature of the load when using it. If it is a fan and pump load, the torque operation code of the 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 during startup and ensure that the torque output by the motor can meet the requirements of production load startup, it is necessary to adjust the starting torque. In the variable frequency speed regulation system of asynchronous motors, torque control is relatively complex. In the low frequency range, the influence of resistance and leakage reactance cannot be ignored. If VPf is still kept constant, the magnetic flux will decrease, thereby reducing the output torque of the motor. Therefore, appropriate compensation should be made to the voltage in the low frequency range to enhance the torque. Generally, frequency converters are manually set and compensated by users.
3. Set the frequency converter to its built-in keyboard operation mode, press the run and stop keys, and observe whether the motor can start and stop normally.
4. Familiar with the protection codes when the frequency converter malfunctions, observe the factory values of the thermal protection relay, observe the set values of the overload protection, and modify them if necessary. The user of the frequency converter can set the electronic thermal relay function of the frequency converter according to the user manual of the frequency converter. When the output current of the frequency converter exceeds its allowable current, the overcurrent protection of the frequency converter will cut off the output of the frequency converter. Therefore, the maximum threshold of the electronic thermal relay of the frequency converter shall not exceed the maximum allowable output current of the frequency converter.
3、 On load trial operation
1. Manually operate the operation stop button on the frequency converter panel, observe the process of motor operation stop and the display window of the frequency converter, and see if there are any abnormal phenomena.
2. If overcurrent protection action occurs in the frequency converter during the process of starting and stopping the motor, the acceleration and deceleration time of P should be reset. The acceleration of a motor during acceleration and deceleration depends on the acceleration torque, while the frequency change rate of a frequency converter during start-up and braking is set by the user. If the moment of inertia of the motor or the load of the motor changes, there may be insufficient acceleration torque when accelerating or decelerating according to the pre-set frequency change rate, resulting in motor stall, that is, the motor speed is not coordinated with the output frequency of the frequency converter, causing overcurrent or overvoltage. Therefore, it is necessary to set the acceleration and deceleration time reasonably based on the motor's moment of inertia and load, so that the frequency change rate of the inverter can be coordinated with the motor's speed change rate.