[rickjohnston]

I am in the planning stages for the wiring of my CNC Mill. I will be using power supplies and a VFD that run from a 220VAC single phase out put from my Wall (USA).

I have a Packard C230B 2 pole 30 AMP Contactor with a 120v coil I plan to use to power the machine on and off, and a second one to disable power to MY VFD on E-Stop.

What is the correct way to use the contactor to power on and off the machine? Should I just break one of the 110VAC feeds or both?

Attached is a preliminary wiring diagram I threw together today.

Thanks!

Rick

[rickjohnston]

Also, I assume that I can grab 110VAC by connecting to one of the 2 voltage legs and ground?

Thanks,
Rick

[Jim Dawson]

The proper way to disconnect the power is to break both hot legs using a 2 pole contactor and breaker.

To have 120V available, bring in a Neutral (normally white wire), do not use ground (green or green/yellow wire) as the return. If you are using a wall plug, this means a 4 wire plug and cable.

[Al_The_Man]

Also, I assume that I can grab 110VAC by connecting to one of the 2 voltage legs and ground?

As per Jim's post do not use ground to obtain 120v, use the correct neutral, if switching the 120v you are permitted to switch both if desired, but if fusing is used it is only in the live conductor, never fuse the neutral.
An E-stop should break all power to motorized devices including the VFD, the controller itself can be left powered.
Al.

[ger21]

In the industrial machines I use, you have a main disconnect switch on the box.
After you turn on the power at the disconnect, you should not be able to activate your contactors until the control software is up and running. Then have a pushbutton to trigger a safety relay, and have that safety relay control your contactors. An Estop loop should run through the safety relay, so that any estop takes out the contactors.
I have the charge pump signal from UCCNC in the Estop loop, which prevents powering the contactors until UCCNC is running.

[rickjohnston]

Gerry, trying to put advice to paper to make sure I understand your comments above. Would you mind looking at my safety circuit diagram to make sure I understood correctly?

One other question I have is about grounds. When wiring the 220VAC the green/copper grounding wire gets screwed directly to the PSU case, which is metal and is also attached to the machines steel frame. Is it safe to also ground any DC outputs to the frame as well? I am thinking about 24vdc relay signals etc...Or should all DC grounds go back to the Motion Controller?

Thanks!
Rick

[Al_The_Man]

One other question I have is about grounds. When wiring the 220VAC the green/copper grounding wire gets screwed directly to the PSU case, which is metal and is also attached to the machines steel frame. Is it safe to also ground any DC outputs to the frame as well? I am thinking about 24vdc relay signals etc...Or should all DC grounds go back to the Motion Controller?

There are two schools of thought, to isolate all DC supplies or bond them to earth GND, In my years of Industrial control, I have always preferred the latter if there is no pressing reason why not, I have never experienced any negative results.
Also all metallic parts of a machine should be earth grounded or bonded, preferably via a common star point earth termination point.
As a point of interest, if the machine controller originates in a PC such as Mach. the P.Port. is at chassis-earth ground via the P.C. power supply.
There are a few posts here regarding spurious incidents such as random shut down that has been eventually cured by grounding of power supplies common.
Al.
.

[rickjohnston]

So, putting everything we have been talking about together, it should look like this?

Thanks for all the input, I definitely appreciate it!

Rick

[ger21]

I'd do things a bit different, but I'm not expert.

You should have a main disconnect to turn power on/off where it enters the control box.
You want the 24V DC supply to come on with the main disconnect, and stay on. The way you have it, I think the UC300ETh will shut down on an Estop, requiring you to restart UCCNC.

I don't see any point in having a contactor controlling the Antek supply, and a relay controlling the output to the drives.

I also prefer my VFD to come on with the main disconnect, and never shut off.

I use an actual safety relay, and have the charge pump in that circuit.

[rickjohnston]

You should have a main disconnect to turn power on/off where it enters the control box.
You want the 24V DC supply to come on with the main disconnect, and stay on. The way you have it, I think the UC300ETh will shut down on an Estop, requiring you to restart UCCNC.

I think this is the case? I added an outline for the control box section, and a few notes as well.

I don't see any point in having a contactor controlling the Antek supply, and a relay controlling the output to the drives.

The first Contactor (the blue one - C2308) is simply an on/off contactor that only reacts the power switch, and nothing else.
The Contactor on the output of the Antek (24VDC Solid State Relay) reacts to the charge pump signal.

With the exception of some power lines, I made anything related to the safety circuit red/pink in color.

I also prefer my VFD to come on with the main disconnect, and never shut off.

Do you disconnect the Power to the spindle after the VFD? We do need to power down the spindle on an E-Stop right?

I use an actual safety relay, and have the charge pump in that circuit.

I tried to do this, but likely failed. The charge pump output from the UC300ETH-UB1 is controlling 2 relays (the 2 red ones)

What I thought this meant is that I would not have power to the VFD and Axis motors until the Main power AND software we good to go.
Then, if an E-Stop was triggered, either through software OR the E-Stop button, the charge pump signal would be turned off?

My first research on charge pumps was this morning so don't beat me up

Thanks for helping me learn,

Rick

[ger21]

Well, if you ask 10 different people how to wire a control box, you'll get 10 different ways to do it.

For my main power, I use a disconnect like this, rather than a contactor.
electrical disconnects, disconnect switches, disconnect switch, manual disconnects, Altech disconnect switch

So, when you turn on the power to the box, it powers the VFD, and the 24V power supply immediately, and they never shut off until you turn off the disconnect.

Do you disconnect the Power to the spindle after the VFD?

Not unless you want to blow up the VFD.
When there's an Estop, UCCNC will stop the spindle. If you don't trust that, you can run your VFD run relay loop through the Estop circuit.

If your Estop kills power to the Antek, then there's no reason for a relay before the drives, as it's redundant. The drives will drain the caps almost immediately, but the motors will stop instantly on an Estop.


And I use a safety relay like this:
https://www.pilz.com/en-US/eshop/001...7-24VACDC-2n-o

This relay controls the main contactor. The Estop loop runs through this relay, so if you hit the Estop, it deactivates the safety relay, which drops the main contactor. I add the charge pump into the estop loop, so that you can't activate the main contactor until UCCNC is running.

[Al_The_Man]

There is also the addition to NFPA70 (NEC), the NFPA79 Electrical Standards for Industrial Machinery.
I always use a contactor on the VFD supply initiated by the E-stop circuit.
Al.