Analysis of overcurrent fault of the hottest frequ

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Frequency converter overcurrent fault analysis

2 The insulation between the motor and the motor cable or each phase to the ground is damaged, resulting in a short circuit between turns or between phases to the ground, resulting in overcurrent

3. The over-current fault is related to the leakage reactance of the motor and the coupling reactance of the motor cable, so the selection of the motor cable is certainly based on the analysis of the control itself, and it will be selected according to the requirements

4. There is a power factor correction capacitor or surge absorption device on the output side of the frequency converter

5. When the speed measuring encoder is installed, the loss or abnormal speed feedback signal will also cause overcurrent. Check the encoder and its cable

21. automatic stop at a fixed time, automatic stop at a fixed deformation and automatic stop at a fixed load in the experiment

second, the reason of the frequency converter itself:

1 Parameter setting problems:

for example, the acceleration time is too short, the proportional P and integral time I parameters of PID regulator are unreasonable, and the overshoot is too large, resulting in the output current vibration of the frequency converter to enhance resources and the integration of inks, adhesives, lubricants, etc. that may directly or indirectly contact food

2. Hardware problems of the frequency converter:

a) the current transformer is damaged. The phenomenon is that the main circuit of the frequency converter is powered on. When the frequency converter is not started, there is a current display and the current is changing, so it can be judged that the transformer is damaged

b) the current and voltage detection channels of the main circuit interface board are damaged, and overcurrent will also occur. The damage of the circuit board may be:

1) due to the poor environment, conductive solid particles adhere to the circuit board, causing electrostatic damage. Or there is corrosive gas, so that the circuit is corroded

2) the zero potential of the circuit board is connected with the chassis. When the cabinet is welded with the ground corner, the strong arc will affect the performance of the circuit board

3) due to poor grounding, the zero voltage of the circuit board will be disturbed, which will also cause damage to the circuit board

c) because the connection plug-in is not tight and firm. For example, if the current or voltage feedback signal line is in poor contact, the phenomenon that sometimes does not exist when overcurrent fault occurs

d) when the load is unstable, it is recommended to use DTC mode, because DTC control speed is very fast, and a group of accurate actual values of torque and magnetic flux are generated every 25 microseconds. Then, through the output of motor torque comparator and magnetic flux comparator, the optimal switching position of inverter is determined by optimizing pulse selector, so as to control overcurrent

in addition, the self-adaptive speed loop (autotune) will automatically adjust PID parameters, so that the inverter output motor current is stable

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