We have a mill (1996 Mastuura) which has a yasnac i80 control. I want to be able to use an M-code to shut down the machine while running unattended operation.

I plan to do this in a sequence

1) E-stop the machine using a relay in the e-stop circuit

2) 1-5 seconds later, turn off the main power switch using a shunt trip (provide a 24v signal to a coil in the main power switch which turns off the power)

I understand that cutting the power to a machine while the servos are powered up is a bad idea. Hence the e-stop. This does happen when the power goes out, but who knows what hundreds of cycles like this would do.

Normally, the human operator would turn the control off before cutting the main power. That's where my question comes from - is it an issue to cut the main power without turning off the control?

Obviously we don't want to do any damage here.

We have a Mitsubishi control which does this. I can see that an alarm is generated perhaps 1 second before the main power is shut down using a shunt trip.

Any thoughts?