VFD (?) tripping RCD

[Jonathan]

First thing is never to disconnect and earth conductor with the main supply still live. This is a very easy way to kill yourself and wont really tell you much.

I know ... I was getting a bit desperate thinking if doing that still got no reading then it implies something's wrong with my earth or my meter. I kept one hand in pocket whilst doing that for obvious reasons. Isolated the supply, connected the meter etc ... switched it on, saw the voltage and switched it off straight away. You're right of course I probably shouldn't have done it.

Do you have a 40 amp mcb and seperate rcd or is it a combined rcd and mcb?

To be precise, It's one of these, which is what trips every time:
http://www.europacomponents.com/prod...%206KA&pso_id=

6A one of these for lighting, and 32A for the ring main.
http://www.europacomponents.com/prod...20Curvepso_id=

Armored cable up the garden (maybe 20 meters) from house to workshop.

a dodgy computer power supply

Using a different computer after the first one just broke, and it's not likely that they're both dodgy.

Does the protection trip with only the router,vfd and the computer/ cnc running?

Yes - but it's only happened whilst cutting.

Can you run the vfd and router on its own without the cnc controller?

Started just that as soon as I read your post ... nothing interesting has happened yet.

You will need an insulation tester to check the windings. A multimeter wont find any high resistance faults.

Ahh, I suppose a multimeter doesn't test at anywhere near a high enough voltage.

Seeing as it only happens after the machine *has been* on for a while that implies something is accumulating, then setting it off. So what could that be, charge, heat...? Maybe the spindle insulation is breaking down once it's been on for a while and causing it to trip. I really hope not as those things are not cheap.