A: Model: GD270-220-4 

Application conditions: General application of water pump speed regulation. 

Fault phenomenon: There is abnormal noise and smoke during the VFD operation for a period of time, and the front switch trips. 

How to solve it?

 Reason analysis: 

Static measurement shows an open circuit in the inverter bridge section. There is no obvious abnormality in the waveform of the power grid measured by the oscilloscope. Upon disassembling the machine, metal conductive dust was found inside. The dust caused the positive and negative busbars to ignite and discharge under the action of the fan, resulting in a short circuit current during ignition and damage to the inverter module. 

Solution:

 Improve the environment and regularly clean up dust. Install insulation tape between the positive and negative busbars to strengthen insulation.

Improvement effect: 

Stable operation.