Spindle pulses on shutting down.

I have a CNC4you driver board , KK01 with spindle relay and I hav it set to contol the spindle by via its onboard relay
My spindle is driven via a 3 phase inverter. As I shut my system down via the computer , the spindle pulses for a second or so .
It does it again as I cut power from the control system. Do others have this problem? I Guess it could be a safety issue so how could I overcome it.?

It shouldn't do that in any circumstance as the relay should be NO so there is no circuit. Could have a relay with burnt contacts or you have bad EMI that is causing the VFD or electronics interference.?

Personally I don't like the cheap relays fitted to Bobs's and would fit an external better quality relay then control that using an output.

Do you have an Earth wire on the Frame going to the Star ground point.? Also, do you have earth on the VFD going to the same Star Gnd point, by that I mean Earth on the VFD terminal and not on the spindle?

What is your shutting down sequence??

Shutting down sequence has been
1 computer
2 power supply to panel
3 All power inc vfd
I have a spur which supplies the no volt relay to the Control panel, but separately supplies the 5 v PSU for the BOB. Will try taking its supply via the NVR.

Problem only became apparent when I added spindle control . BOB relay is only switching a 24v signal to the VFD

That has done the trick. Maybe should have spotted that sooner but thanks for setting things straight in my mind Jazz

Will check out ( and sort ) the earthing arrangements at the vfd

I tend to shut down in the reverse order exaxctly because of the risk of spuirous pulses flying around the system: VFD then controller and PC last of all. Obviously the power up is the reverse of this. It just seems sensible to first dissable the the part that moves, then the part that controls the movement, then the part that issues the instructions to move.

Sensible indeed ! As I said it wasnt a problem until I added spindle stop /start. but even when starting the computer it pulses as you switch on the mains .
I think I need to bring the VFD under the control of the NVR.

This thread could easily drift for me as it leads to questions about spindle relays and VFD problems .
In the interests of good forum etiquette I will start new threads.