VFD (?) tripping RCD

[m_c]

Ah, you did mention that (I've been helping a mate move house today, so am currently a bit tired!).

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.

[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!

[mocha]

Assuming you haven't overlooked anything or missed something in the tests you have already done... It sounds similar to a problem I had with radios some years ago. ...

Bring some power from the house or from next door! but bypassing the RCD unit, with a standalone RCD if necessary, (but if you are happy to have a hand in your pocket while disconnecting earths you probably wont want to! lol)

Try plugging each of the suspect items; the VFD? into the extension lead with everything else plugged into the main RCD, as soon as it stops dying or the problem disappears you have the suspect device cornered for further investigation

or... find a way of removing DC from the AC line back to the RCD, or split board supply??

The RCCD you point to; 40amp? is it 30 or 100 mA?

[NB70]

Jonathan,

there's been discussion about this recently on the EMC2 mailing list - something to do with filters in the VFD providing a path to earth - which then trips the RCD. So it might not be a fault per se, just the way the VFD is designed to work. I know Andy Pugh and others experienced this issue (and hopefully solved it). He frequents the EMC2 forum - it might be worth asking a question over there:

Link: EMC2 forums

Nathan

Sorry Jonathan just re-read your post properly - since your set up was working fine for a year this is unlikely to be the cause