It must be the week for VFD problems.
The spindle VFD on my lathe started tripping the RCD this week. Wouldn't of been so bad, but the first time it went I had just pressed the button to save new settings on the servo drive I was in the middle of tuning. I thought I'd somehow screwed up the servo drive!
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In my case, removing the cover and blowing all the dust out seems to of cured it. I still need to use it in anger, but I'm hoping it was just a combination of the dust and some dampness, as I don't like the prospect of the bill to replace it :-/