Marshalling Cabinets Design
Marshalling Cabinets Design
(OP)
Hi All
I'm a new member on this forum and really hope to get some tips and of course share my knowledge and experience.
The first one from me, is with regards to DCS/ESD marshalling cabinets.
On various projects I've seen that digital and analogue marshalling cabinets were split, and in some project they were combined. I've been looking through API 554 standard and there is nothing about it over there. Is there any particular reason to split marshalling cabinets by digital or analogue type?
Many thanks for your advice
I'm a new member on this forum and really hope to get some tips and of course share my knowledge and experience.
The first one from me, is with regards to DCS/ESD marshalling cabinets.
On various projects I've seen that digital and analogue marshalling cabinets were split, and in some project they were combined. I've been looking through API 554 standard and there is nothing about it over there. Is there any particular reason to split marshalling cabinets by digital or analogue type?
Many thanks for your advice





RE: Marshalling Cabinets Design
http://www.plctalk.net/qanda/showthread.php?t=8991
Francis
www.controldraw.co.uk
www.s88control.blogspot.com
RE: Marshalling Cabinets Design
Looked through few pages but didn't really manage to get the answer.
Is there any reason to segregate analogue with digital marshalling cabinets.
RE: Marshalling Cabinets Design
The analog and digital are usually in separate junction boxes in the field, with multi-conductor 'home run' cable to the marshalling cabinets. Running to two separate cabinets may make conduit layout easier.
Ergonomically, for the technicians, one might choose to keep the two signals in separate cabinets, so there is no confusion with troubleshooting, parts, installing new, etc...
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This is normally the space where people post something insightful.
RE: Marshalling Cabinets Design
Then there is another question with regards to IS and non IS.
Are there any reasons to segregate them in different cabinets?
My understanding that it is easier from the cabinet layout and constructin pont of view to segregate them, but I do not really see any technical reason for not combining them.
thanks a lot
RE: Marshalling Cabinets Design
Also, on the digital vs analog: if both are 24vdc, then they can be run together. If digital is higher voltage, i think you can still run the analog with it up to a point, but not recommended. I like to keep them separate for clarity.
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This is normally the space where people post something insightful.
RE: Marshalling Cabinets Design
My IS experience is rare as few of my clients want that for their normal process. The IS separation rules were significant to avoid higher voltage and current to exceed the IS rules. Some tricks seem to exist without the one-ohm grounding system etc. that existed decades ago.
I would absolutely separate IS analog from digital signals; and likely IS from not-IS.
I can power a non-IS transmitter with 24 Vdc 35 amp power supply. With the IS loop the barrier etc. (and not checking the standards) limits the signal current under about the 100 mA level. With adjacent pairs in a junction box or marshaling cabinet seems like trouble.
Again, I would have to check current standards to get this straight and don't have time.
RE: Marshalling Cabinets Design
Let me do some research and I'll post back on what I've found
Regards
RE: Marshalling Cabinets Design
We tried to run separate cable trays to keep them separated. In large plants, it's easier and you don't have to worry about tens or hundreds or thousands of loops adding up to enough power to make a difference.
However, there were exceptions to the rules and the rules were bent or broken but not often. If it is not a safety issue, economics can rule.
I would keep IS separate from non-IS. I worked in one plant that used IS so I cannot comment about how prevalent different wiring practices are. Hopefully they follow NEC.
RE: Marshalling Cabinets Design