A well assembled box from a 508A panel shop is indeed a thing of beauty and a credit to the skill and pride of the assembler.
Mike Sherman
Graco Inc.
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------ Original Message ------
From: Doug Powell
To: EMC-PSTC@LISTSERV.IEEE.ORG
Sent: April 4, 2017 at 11:26 AM
Subject: Re: [PSES] E-Box Layout on Factory Machines
-Just my opinion but the use of heavy locked enclosures (pre-dating DIN Rail) has been industry practice for many years. I suspect that part of the reason of enclosure similarity is from the desire to keep costs down by having a minimum number of different boxes in inventory. In addition, NEMA has quite a bit to say about design for enclosure strength, ingress, accessibility, etc.As for the harnesses I feel DIN Rail is a result of organized wiring layouts, not a cause, I have worked with systems when everything was connected with ring lugs and very long terminal blocks. It may not be so obvious on smaller systems but larger systems are often very configurable and rather complex. This made it much easier to manufacture harnesses in quantity on plywood board and nail setups with each conductor is identified and tagged on both ends. I learned my electronics on radar and countermeasures systems in the US Navy and we had to have wires harnessed and secured cable in this way. I even learned to tie the standardized knots to use on harness lacing twine. I haven't checked in a few years but this may still be a practice in military equipment and I'm pretty sure in avionics too. In industry, the tywrap has all but taken over. I suspect many of the MIL STD practices have made their way into industry because they have been proven to work.In the early days of mainframe computers, there were attempts to dress out wiring in a similar fashion and it was found that the cross-talk between conductors could actually be detrimental. This was likely one of the contributing factors to the old "rats nest" and thick blankets of 30 AWG wire used in wire-wrapped backplanes and main frames. The more or less randomly routed wires were less likely to cross talk when laid out in quasi-orthogonal arrangements and when squeezing out every bit of speed was imperative, direct point to point wiring was just a tad bit faster. Just for fun, try a google image search for Cray Computer Backplane. It becomes very apparent why technicians would pull out their hair.-On Tue, Apr 4, 2017 at 6:54 AM, Kunde, Brian <brian_ku...@lecotc.com> wrote:-I notice that most industrial factory machinery is designed with a large metal electronic box with a hinged door and some kind of keyed lock. Inside the components are DIN mounted and the wiring is all dressed very neatly in these gray plastic cable runs with snap-on lids. Every wire is labeled with a small tag.
Why are these machines so similar in design? Even among different manufacturers, they look similar. Is there a standard or standards that dictate exactly how this is done? What criteria is used to determine if your product must follow these construction rules?
Seems strange to me that they are so similar and if required to be that way, then standards and/or governments are dictating design. Even if it was for the “greater-good”, I thought that was a no-no. Dictate design, stifle creativity, invite those who would take advantage for financial gain.
Just curious. I’m most interested in the criteria question, though.
The Other Brian
LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you.
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