Ready Steady Eddy

[EddyCurrent]

Good timing lads !

@silyavski, the temperature switch was already built into my spindle, it is closed normally and opens at high temperature.
@cncJim, see latest drawings

Here are my latest drawings



Features
---------
Strategy 1

* Emergency stop immediately signals VFD to stop and several seconds later (time to be assessed but possibly 6 seconds) delayed contacts of Guardmaster safety relay open to operate STO (Safe Torque Off) feature of VFD which disables control voltage and power semiconductors.
* Power removed from Stepper Drivers via Guardmaster safety relay and K1
* Stop command issued to Mach3 via K1 (even if Mach was still active the VFD and Stepper Drivers would still be disabled)

Strategy 2

* Stop signal sent to VFD via K3 relay
* Stop command issued to Mach3 via K3
* Enable (ENA) signal activated via Mach3 and BOB to disable stepper drivers

Strategy 3

Not implemented - same as Strategy 2

Strategy 4

* Stop signal sent to VFD via K4 relay
* FeedHold command issued to Mach3 via K4
* Enable (ENA) signal activated via Mach3 and BOB to disable stepper drivers

Strategy 5

Not implemented


Notes:

Strategy 3 could be implemented by incorporating a relay contact from K3 into K1 coil circuit however because all 4 contacts of K3 are being used another single contact relay would have to be connected in parallel with K3.
Strategy 5 could be implemented by removing the Pause push button and having only K4-4 contacts operational.

* A PAUSE push button has been added, this will stop the VFD and send a FeedHold signal to Mach3, to continue the ON (RESET) push button is pressed.
* A Charge Pump relay has been added to the Emergency Stop circuit this so the system can initiate an Emergency Stop if the software stops or communication is lost.
* If the Circuit Breaker for the Stepper Drivers trips then K1 will de-energise and send a STOP signal to Mach3.
* ENA signal now connected from BOB to all Stepper Drivers

( ** As yet I have not cobbled together the Charge Pump relay but I think a small 5v coil one will do the job as my BOB can source 20mA. **)

Relays K2,K3 and K4 are these
http://www.ebay.co.uk/itm/1set-Base-...item5d388b7d84

[cncJim]

Good timing lads !

...

( ** As yet I have not cobbled together the Charge Pump relay but I think a small 5v coil one will do the job as my BOB can source 20mA. **)

Good stuff EddyCurrent, I'm still working my way through your diagrams trying to fully understand :) - Do you have any provision for activating your estop circuit from the controlling software? I suppose the argument could be made that its not needed unless the pc a distance from the machine?

Relays K2,K3 and K4 are these
1set Base+OMRON coil power relay 14pin 4NO 4NC MY4NJ MY4N-J 5A DC24V 4PDT | eBay

I have just acquired 10 of these from a control panel I stripped down (7x 24v and 3x 230v) which seem to be a similar spec to yours:-

Finder TYPE 55.34
The 5A rating, is that for the entire relay or for each contact?

There are also 4 contactors which I haven't taken out yet. Are there any practical/safety differences between a relay and a contactor?

[EddyCurrent]

Good stuff EddyCurrent, I'm still working my way through your diagrams trying to fully understand :) - Do you have any provision for activating your estop circuit from the controlling software? I suppose the argument could be made that its not needed unless the pc a distance from the machine?

Yes that's what the Charge Pump relay is doing. The BOB is turning a 12khz signal from Mach3 into a 0 or 5vdc output, on my particular BOB the output of ENA is 0v when Mach3 is healthy and +5v dc when it stops.

I have just acquired 10 of these from a control panel I stripped down (7x 24v and 3x 230v) which seem to be a similar spec to yours:-

Finder TYPE 55.34
The 5A rating, is that for the entire relay or for each contact?

Those look just right, I looked on Farnell and they appear to be 4 pole Change Over which is what you need if using my diagram, the 5A rating is for each contact.

[cncJim]

Yes that's what the Charge Pump relay is doing. The BOB is turning a 12khz signal from Mach3 into a 0 or 5vdc output, on my particular BOB the output of ENA is 0v when Mach3 is healthy and +5v dc when it stops.

Of course, what a spanner! sorry that makes perfect sense now.

[EddyCurrent]

There are also 4 contactors which I haven't taken out yet. Are there any practical/safety differences between a relay and a contactor?

With electrical systems there are generally two main circuits, the 'control circuit' and the 'power circuit'. Contactors are regarded as components of the power circuit whereas relays belong to the control circuit, it's mostly to do with the current carrying capacity and the ability to break that circuit without arcing or at least controlling the arcing. There are relays with positive guided contacts and these are for use in safety circuits, I have not come across equivalent contactors but that's not to say they don't exist. I'm not 100% on this but I think relays originated in communications areas such as telephone exchanges. Contactors can have auxilliary contacts fitted which in essence are relay equivalents and are used in the control circuits for those contactors.