VFD power input causing RCD to trip

This VFD drive ACS550-01-012 which was used before has its inputs is wired as L1 L2 L3 and PE as in following diagram without any motor installed causing an RCD to trip the moment I turn on the 3 phase switch:



When I encountered it the power input looked like as follows:



So someone had wired neutral(blue wire) to PE as well. So I first thought that could be the problem. But then I removed the neutral and the RCD issue was not solved. Now it is wired as in the diagram L1 L2 L3 and PE. But still the RCD was tripping.

So eventually I also removed the earth and the VFD started without a problem. But in this case I'm violating the safety, since the device is not earth grounded.

According to **broken link removed**document the type of the RCD in my case must be Type A from the symbol and here is the photo of the RCD:



I could only find this document and not much information about such issue. So obviously there is some earth leakage current at the start which does not let the VFD to start at all. I checked line to earth by continuity connections and there is not fault. What could be the problem in this case? Can this be due to wrong type of RCD? (I also heard it was working from the same power outlet system some years ago but I'm just not sure 100% of this information).

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I learned that they were not suing RCD before. And without RCD the drive works now. Somehow probably due to built in filters earth leakage current is much higher in VFD applications I guess..

Hi,

So someone had wired neutral(blue wire) to PE as well.

Click to expand...

You may do this without RCD.
But with RCD this will make the RCD to trip. Never connect neutral and PE after the RCD.

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So eventually I also removed the earth and the VFD started without a problem. But in this case I'm violating the safety, since the device is not earth grounded.

Click to expand...

Don´t disconnect PE .. since this will cause a safety issue.

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Photo:

Input cable: Most left one, grey.
Three phases are correct.
* Where does the yellow/reen one go to?
* Where does the blue one go to?

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At the top picture there is a shielded cable for the breaking resistors and there is a shielded cable for the motor. I don´t know if this is a must, so please check this.

Klaus

It's a known problem with many VFD. Large Y capacitors in input filter cause RCD tripping. If RCD is mandatory in your installation, e.g. for plug connected VFD applications, try installation manual procedure "Disconnecting the internal EMV filter".

Thanks for all of you nice replies.