Danfoss inverter maintenance vlt5000/vlt6000/vlt8000

Precautions for Danfoss frequency converter maintenance ：

First, check whether each broadcasting port of the frequency converter is correctly connected , Whether the connection is loose , Abnormal connection may sometimes lead to failure of the frequency converter , In serious cases, the aircraft will explode . Check the fault display after power on , And preliminarily determine the fault and cause . If no fault is displayed , First, check whether the parameter is abnormal , And reset the parameters , Carry out no-load test （ Not connected to the motor ） Start the frequency converter in case of , And test the U、V、W Three phase output voltage value . In case of phase failure 、 Three phase unbalance, etc , The module or drive board is faulty . When the output voltage is normal （ No lack of phase 、 Three phase balance ） Under the circumstances , On load test .

Caused by grid voltage or internal short circuit . After eliminating the internal short circuit , Replace the rectifier bridge . When handling faults on site , The power grid condition of users shall be emphatically checked , Such as grid voltage , Whether there are electric welding machines and other equipment that pollute the power grid . The update of devices has led to the continuous development of power electronic conversion technology .20 century 70 In the beginning , Pulse width modulation variable voltage variable frequency (PWM－VVVF) The study of speed regulation has aroused great attention .20 century 80 years , As a frequency conversion technology PWM The problem of pattern optimization attracts people's great interest , And many optimization models are obtained , Among them, saddle wave PWM Mode effect .

 

The frequency converter is classified according to the working mode of the main circuit , It can be divided into voltage type inverter and current type inverter ; Classified according to the switching mode , Can be divided into PAM Control frequency converter 、PWM Control frequency converter and high carrier frequency PWM Control frequency converter ; Classify according to the working principle , Can be divided into V/F Control frequency converter 、 Slip frequency control frequency converter and vector control frequency converter, etc .

that , What causes the overload trip of the frequency converter ： Partly because of the heavy load ： The load on the motor is too heavy , Or the resistance torque of the production machinery exceeds the rated torque of the motor , This is a common overload phenomenon , therefore , When the tripping code of the frequency converter is displayed as ‘OL’ when . And connect the steel pipe shell or cable shielding layer with the earth .

Without adding AC output reactor L3 when , If steel pipe threading or shielded cable method is adopted , The distributed capacitance of output to ground is increased , Prone to overcurrent . Of course, in practice, only one or several methods are generally adopted .

 

In the design process of the control system composed of Frequency Converter , It is recommended not to use analog control , In particular, the control distance is greater than 1M, Cross control cabinet installation . Because the frequency converter usually has multi-stage speed setting 、 Switching frequency input and output , Can meet the requirements . If analog quantity control is not required , Shielded cable is recommended , At the sensor side or frequency converter side, a remote point grounding is realized . If the interference is still serious , Need to achieve DC/DC Shielding measures .