I checked the claim that the spindle is grounded, and indeed the 4th wire (pin 4 of the aviation connector) is connected and has continuity with the spindle body (I checked with a multimeter). Good.
- the input 220V power plug I will use has live, neutral, and earth.
- I plan to use a 4core 1.5mm² cable I have on hand, to wire the spindle pins 1/2/3/4, to terminals U/V/W and Earth of the VFD.
So I would end up connecting both the earth wire from the 220V plug and the earth wire from the spindle body, to terminal 9 (Earth) of the VFD:
Which sounds consistent with the diagram on the first page of this (very interesting) guide I stumbled upon:
but since earthing details are scarce in the posts I found here on the forum, I thought I would double check here.
Also, my 4 core wire is not shielded : from your experience, it is worth going for a shielded 4core cable instead, to prevent any possible EMI issue ?