G0704 CNC Conversion (yes, another thread on this :) )

[macardoso]

Read this again. One final comment. Many electronic devices require a conductive path through the subpanel to ground for noise mitigation (bonding). A plexiglass sheet won't provide a conductive path (obviously) so it is especially important to make sure to install a ground bar (tie this to your utility ground) and ground each device that has a ground stud back to this central location. Any DIN rail can be grounded to the ground bar by installing a grounding terminal block on the end of the rail.

 

[wachuko]

Read this again. One final comment. Many electronic devices require a conductive path through the subpanel to ground for noise mitigation (bonding). A plexiglass sheet won't provide a conductive path (obviously) so it is especially important to make sure to install a ground bar (tie this to your utility ground) and ground each device that has a ground stud back to this central location. Any DIN rail can be grounded to the ground bar by installing a grounding terminal block on the end of the rail.

Got it. Will get a grounding terminal block. Thank you.

 

[wachuko]

Playing with the layouts...

Option 1



Option 2 - Don't mind the cable organizer, I did not wanted to cut any more until I decide on the layout to go with. Those will be full length



Some other layout suggestions?

 

[wachuko]

Option 3 - with these two options the power supply are on the bottom and fixed against the case... metal to metal. Helps with the ground. I will still get the ground block for anything that would require it in the rest of the setup.



Option 4- with these two options the power supply are on the bottom and fixed against the case... metal to metal.

 

[macardoso]

I like option 4. Fan blowing across the drives.

 

[wachuko]

I like option 4. Fan blowing across the drives.

Can you share a recommendation for the type of thermal breaker to use? I lost those when the site had problems.

 

[macardoso]

Pretty much any thermal magnetic breaker with a Class C trip curve. If you were doing this according to code, you’d need to select one that is rated for branch protection.

An example of high quality breakers would be the bulletin 1489-M breakers from Allen Bradley. Honestly I’d just get what Automation Direct has to offer.

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Single pole for 120VAC, double pole for 240VAC. Do not break the neutral.

Downstream of this breaker, you are free to use “Supplementary” type breakers. These are cheaper and more compact. In my CNC control, I use one 50A branch protection breaker and then individual 10A supplementary breakers for each servo drive.

 

[wachuko]

The challenge that I have is selecting the correct amperage for the breaker... feeding for this project is 120v not 220.. Not sure what the max draw will be at any given time to decide on the amp for the breaker...

I have seen folks using a breaker for both positive and negative... should I be doing that as well?

Also, just saw the blocks that are mounted on the rails... I had ordered a regular one... going to order one that mounts on the rail... I have to switch my thinking to rail mounted components...

Incorrectly ordered this:



Now ordering this (comes with the jumpers):

 

[macardoso]

That first big terminal block could pass as a ground bar in a pinch.

To do it correctly, your DC should have some kind of circuit protection. Typically only the positive would be fused. The DC common would be left connected directly. Often the DC common is tied to earth ground but may be left floating for added noise immunity in EMI sensitive circuits.

Your switch mode power supply should self protect and disable the output if it is shorted or overloaded. I’ve built stuff in the past with no DC protection, but it isn’t the right way to do it.

Automation Direct has a great price for terminal blocks. I think $0.20 each in a box of $100. Get those with some end barriers, jumper bars, and anchors and it will last you a long time.

 

[wachuko]

Went with layout option 4... all components now secured: