First attempt at industrial control panel. - Page 1
Forum section: electronics / beginners

author: calzap
author_rank: Frequent Contributor
timestamp: November 02, 2020, 07:12:39 pm
content: It’s a relatively simple project for an ICP (small and no PLCs) ... actually, more in the style of an ICP than a true ICP. I wanted some experience for a bigger project coming up that will use PLCs. It’s a controller for a milking machine (for goats in this case). Essentially, it’s a vacuum pump controller with multiple manual start/stop mechanisms and a safety mechanism. For those who aren’t familiar with milking machines, they don’t just suck the milk out; they also massage the teat. That function is accomplished by a vacuum-powered mechanical timer and flexible teat-tube liner; it won’t be covered here. The vacuum pump is also part of the process used to clean equipment after milking is over. All outlets in the milking parlor are GFCI-protected.The vacuum pump is connected to a vacuum chamber which has a mechanical vacuum regulator. Between the vacuum chamber and the rest of the equipment is a much smaller safety chamber with a float switch. The purpose of the safety chamber is to shut off the pump if liquid (milk or cleaning fluid) enters before it reaches the vacuum chamber or pump. One unintended consequence of the safety chamber is milkers exhibiting risk-compensation … they often suck in enough cleaning fluid to reach the safety chamber, especially because it has a manual drain valve that they can use to reset the float switch. This provides frequent tests of the float switch!Milkers prefer a wireless control over fixed position switches. That way they can carry the small transmitter around with them as they move about the animals and equipment. The original controller had an external wireless switch that carried the entire electrical load. However, its inductive rating was below the draw of the vacuum pump (won’t say who made that mistake). So, it periodically failed and had to be replaced. The main goal was to incorporate a wireless switch that had to handle current for only a relay. The controller needed to be robust … a milking parlor is a rough environment.First pic is an inside view of the original controller. Second is switch/indicator view of original controller. Third is the 120 VAC output side of original controller (pump plugs-in here). Forth is schematic of new controller. Fifth is layout diagram of new controller. Sixth is inside view of new controller. Seventh is view of innards of indicator/switch box with radio receiver on top. Box wiring would have been neater with a perfboard or PCB, but not worth the effort for a 2-off project. Eighth is switch/indicator view of new controller (small white box is the radio receiver). Ninth is 120 VAC output side of new controller (pump plugs-in here).I use Visio for doing layout drawings. I have a lot of experience with the program and a big library of components. I can easily make drawings of components that aren’t in the library. There are specialized programs for creating ICPs, but they are too expensive for me.Milkers are very happy with the new controller.Main lessons for a beginner like me:1. Layout rails, ducts, and actual components (or realistic cutouts) on a table before ordering the enclosure … you’ll need a bigger one than you initially think. You may also need room for a fan or two and some wire bending space for wires and cables passing through the wall of enclosure. And provide plenty of depth … there’s the standoffs for the back panel, thickness of the panel, DIN rail, perhaps DIN-rail-clips, … then comes the height of the components and some of these may have to accommodate plugs, wire bends or quick connects on top.2. Although it’s common to have switches, sockets, noisemakers, and indicators on the door or sides of the main enclosure, I prefer them to be in smaller boxes (as few as possible) attached to the main enclosure. This minimizes the number of holes to be made in the enclosure and makes it quicker, neater and cheaper to do the inevitable future changes.3. Choose a common brand of DIN terminals that has been around for a while and stick with it. Dinkle, Entrelec and Phoenix Contact are high quality brands ... loads of options and widely available. I chose Entrelec and have been happy with it. Realize that lots of study will be required … mostly in digital catalogs … to choose and use terminals properly. Terminals have their own lingo, which must be learned.4. There are some good videos on ICPs on youtube and elsewhere on the net. Watch them.5. A few, inexpensive specialized tools, like a ferrule crimper and screwdrivers with long, thin shafts, are needed.6. If possible, spec components that are DIN-rail-ready. There are a variety of clips and platforms available for components that aren’t DIN-rail-ready, but it may take some searching to find the proper ones for a particular component. Worse case, you may have to make a platform from sheet plastic and screw DIN-rail clips and the component to it. Look at the contactor in the new controller for an example.Mike in California

author: Dave8266
author_rank: Contributor
timestamp: November 02, 2020, 07:27:07 pm
content: Has anyone given you feedback yet on the Enable/Disable switch changing directions?I would think the new "up=on" orientation is more intuitive (it's the convention we expect from a lifetime of using light switches), but certainly there will be some muscle memory to overcome for the users of this system who are used to flipping the switch down to turn it on...

author: calzap
author_rank: Frequent Contributor
timestamp: November 02, 2020, 11:13:11 pm
content: Quote from: Dave8266 on November 02, 2020, 07:27:07 pmNo, the change occurred to me when I was designing the new version. The enable/disable switch and override switch ("test" on the old version) are intended to be used primarily for diagnostic purposes. I can't recall the milkers ever using them. If the wireless switch and pendant switch don't work, they call for help.Most common problem with the overall system is clogging of air filters on the vacuum pump.Mike in California

author: elekorsi
author_rank: Regular Contributor
timestamp: November 03, 2020, 12:02:50 pm
content: Few things that are the mostcritical:-missing main disconnector switch-no protection elements (fuses, circuit breakers)-RCD? (not sure about this one, but since it is a milking application i assume there is a chance of water contact)-none of elements are marked (neither in drawing or in cabinet)Things that could be better, but are not critical:-wire arrangement-big 24V transformer (for control supply, better to use 24VDC switcher instead, much smaller, less heat dissipation)-drawings (i am from IEC country, but all drawings from UL countries were much more readable than this), to much information crumbled on one page-if we are talking industrial cabinet, then use industrial components (switches, indication lamps, etc.)As i said, i am no UL specialist, but i am not sure that wire colors are correct.For theIECis it like this:AC and DC power - BlackNeutral - Light blueForeign power or power before main disconnector - orange+24VDC control - dark blue0VDC control - blue with white strip230VAC control - redI would be glad if someone could list them for UL here.

author: calzap
author_rank: Frequent Contributor
timestamp: November 03, 2020, 09:42:14 pm
content: It was never intended to meet the standards of UL or any other certifying agency … nor must it ... the goat dairy is mine and is non-commercial. As I said in the write-up, it was done in the style of an ICP, but isn’t actually one. As a small motor controller, it meets NEC standards … plug cord can be used as the disconnecting means as long as it is in sight of the motor, which it is. And OLP can be built into the motor, which it is. Mains power wire colors meet NEC and UL standards. I deliberately chose to use different wire colors for different functions for 24 VAC in lieu of labeling. It does have a fuse as specified on both drawings, and all elements are marked in the layout drawing. As mentioned in the write-up, all outlets in the dairy are GFCI (RCD) protected.Yeah, the wiring in the switch/LED box could have been neater with a PCB or perfboard, but it wasn’t worth the effort because at most, only two of these would ever be made.You can find mains wire color standards for all countries on Wikipedia.Mike in California

author: elekorsi
author_rank: Regular Contributor
timestamp: November 04, 2020, 07:49:36 pm
content: OK, i understand, i first thought that it is a commercial application. All my comments are meant in a positive way and i hope that you don't feel offended...And i apologize for that RCD, i am not used of the name GFCI, so i completely missed it...And i see the fuse now in the diagram... The problem is, that i didn't saw it on first look, as the diagram is not as readable as i am used to. I attached an example of the typical diagram of industrial control cabinet. (i deleted the footer data as it involves my personal and customers information). This is one page taken out of project and represent one induction motor FW/REV driven directly. You can see what i meant with the markings, each component must have its unique name. For example, the contactors have the "K" in the name and simplest way of designating them is with: -K1, -K2, -K3. On this particular drawing you see -18K1 and -18K2, this means that they are on page 18 (there are many ways of designating them, as long as they have unique name). When you open the cabinet and you see the contactor with the label -18K2, you will simply open the page 18 and there it is.As i said, i can only give you an examples of european (IEC) style, but i know that there is quite a lot of similarity with the US (UL) style.You must make the drawings as readable as possible, this means, break it up on more pages. You make a page for each separate functional part of the cabinet/device.All this i wrote, because you said that you are preparing for a bigger project and it is easy to get lost and confused in your own project if you don't don't do it properly. Especially when you need to do some maintenance on it after some years and you don't know what you are looking at...For the wire colors, i know that there are some on wiki for the mains. But i am more curious about those 24VDC, 0VDC, foreign power, etc.Would be nice if someone would tell me what are you guys in US or in Australia using for those...

author: calzap
author_rank: Frequent Contributor
timestamp: November 04, 2020, 10:38:42 pm
content: Thanks for your comments and for the demo drawing. I considered breaking my drawing into multiple pages and see the advantages. Actually, my layout drawing prints as separate pages. I pasted them together for my helper to use. He doesn’t know much about electronics, but is good at assembly as long as there is a realistic (picture-like), complete drawing to use.The bigger project is a pump controller. I completed the design using relay logic. Then after getting the parts together, it was so complex physically (11 relays!) that I decided to learn PLC programming. I’m in the process of doing that, but it will take a while. I’ll probably use Click PLCs (made by Koyo and sold in the U.S. by Automation Direct). They’re among the simplest to program, and Automation Direct provides a lot of support for beginners. And the new project will be a lot closer to a real ICP than the milking machine controller.The UL code for ICPs is UL 508. I believe it incorporates standards of NFPA 79, Industrial Machine Safety. NFPA is the National Fire Protection Association, which is a private non-profit that develops model codes for fire and electrical safety. NFPA 70 is the National Electrical Code. Siemens gives a good summary of UL 508 on their website, including wire colors:https://assets.new.siemens.com/siemens/assets/api/uuid:6826bcbd-f0a9-476b-bef9-9ab23763f167/controlpanelna-guideline-icp-us.pdf. Intertek (alternate certifying company to UL) gives a good comparison of U.S. and European ICP standards on their website:https://www.intertek.com/uploadedFiles/Intertek/Divisions/Commercial_and_Electrical/Media/PDF/Life_Safety_and_Security/Machinery_NFPA_79_v_EN60204-1.pdfMike in California