Power Supply Proximity?

[safeairone]

Just getting around to building the control cabinet for my own design 4 x8 router and wanted to head off any issues early on...

Will the placement of the 72VDC power supply (lower right corner in pic, below) be problematic for the Masso controller above it, electrical interference-wise? I m trying to keep the AC stuff (lower left bay) separate from the DC stuff (middle bay) as much as possible, though we ll see how much I can follow this concept within the wire ducts.

Thanks,

Mark

 

[radiola]

Hi mark,

That's a neat layout! by the looks of it you'll be fine. You may already know this but for the benefit of others, if you tightly twist your DC supply lines (that go to drives etc) you will greatly decrease the magnetic flux around the wires which will make them less noisy to signal wires. I put two ends in a cordless drill chuck and pull the trigger, you'll have a perfectly formed and tightly twisted DC power cable for each of your gecko drives. VFDs are very noisy things. Mine is going as far away from my Masso as possible - the right hand side of the panel which is next to the outlet glands. Ideally i put VFDs in it's own box but with careful wiring and layout they're fine. Also, consider putting a snubber diode across the coil of your contactor. the back EMF from these can cause a voltage spike and hurt your masso if it lives on the same power supply.

 

[safeairone]

Hi @radiola ,

I see you and I think alike regarding in-panel housekeeping!



Good point about using twisted pair wiring from the power supplies. Also, I ve quickly run out of room in this 24 x24 electrical enclosure, so I plan on bolting a second, small enclosure to the side of this one to house the VFD and associated electrical components, with the added benefit of having that noisy stuff isolated in its own metal box/shield.

As for the snubber diode...I ll have to put some thought into this; I m enamored with this push-button remote on/off switching method detailed in this short video by Galco, with the circuit pictured below: The Masso s 24v power supply (among other things) will be the load in the diagram. I m not sure where to put a snubber diode into this circuit or if it is even necessary.

Mark

[EDIT]: Just realizing that my coil is a 110VAC-actuated coil. I really have to study up on snubber diodes and their uses/employment now, as it won t be as simple as putting a diode across the coil in reverse polarity.

 

[radiola]

Hi Mark,

You won't need a diode on that contactor as it's an AC coil. Normally the 24vDC versions have quite a powerful electromagnet inside that causes a considerable spike on the 24v line when they release or fire in quick succession. More so when you have a few of them firing off. This can be observed on a CRO. The traditional practice was to put simple diodes across the coil to mitigate any back EMF the coil might cause. This was true of some air solenoids. I have seen HV ceramic caps used as well.

Yes We do think alike re cabinets. I just began putting the larger one together having maxed out the other one i built! As usual I don't build to plans and get carried away. I have a huge supply of control automation gear and i like to use it where i can. Like you, my previous box was going along side the VFD box but of the 50 or so used cabinets i have, none matched and they stood out like the proverbial. make sure to mark you wires for easy troubleshooting down the track! I opted for one large one and hopefully with careful layout i'll get away with it. Pictured is the previous one i stopped work on a few days ago.

Still, I'd rather fuss about now than halfway through an important job and a deadline!

Cheers

Ant