VFD (?) tripping RCD

[Jonathan]

I'd be more inclined to try it with an ammeter, as that way things are still tied to earth, and give a better idea if it's something slowly building to tripping point, or something causing a more sudden spike. Of course an oscilloscope would be better, but you may as well try with what tools you've got to hand first.

I have so far only tried it with the ammeter. Oscilloscope (http://uk.farnell.com/gw-instek/gds-...our/dp/1563796) goes down to 2mV/div ... so I could in theory use an about 0.5ohm resistor and it'd still show 30mA.

Spindle is still running ... that's been over half an hour. Only difference I suppose is it's now running unloaded, so not going to heat up much unless I restrict the cooling. Not going to try that as I'm a fan of non destructive analysis!