3-Wire RTD (termination designations)

[MESC1]

What is a good genaric terminal designation for 3-wire RTD's?
Let me elaborate on why I need assistance... RTD's generally don't come with any kind of terminal designation. In my company we determine a portion of our wire markers by the terminal designation of the end device. This insures thay are all unique. Where those designations don't exist we apply genaric but commonly understood designation. This is easy enough if you are talking about a pilot light, H and N or +24 and COM work well. But in the case of RTD's it's just not as obvious to me. I have seen Red, White and White, although that really doesn't explain the service. Also that gives two wires the same wire number, that's bad business; they're not hitting the same point on the PLC or in the customer's DCS. Today someone suggested +, -, and -. Again this lacks a unique numbering. Also, until today I'd never seen that on an RTD, it seems strange to me. I've also seen RTD, Sense, and Return, but that is awfully long to put on a wire marker.
Basically if you could offer me some opinions on how this should be labeled, and what is commonly understood in the industry I would appreciate it.

Thanks
SC

 

[GTstartup]

We use +,-,- as you mentioned. The - and - are not unique because they dont have to be since they are common. The device that is measuring is connected to + and - and the compensation wire is connected to the remaining -.

If you don't like this, i suggest r1, r2 and c where r1 and r2 are the resistance and c is the compensation.

 

[dbaird]

Check:

http://s46.yousendit.com/d.aspx?id=174W558HFGNC534BMMXFSAS7V4

David Baird
mrbaird@hotmail.com
Sr Controls Designer
EET degree.
Journeyman Electrician.

 

[itsmoked]

In your *case* (and I understand it all too well) I would call them:
+, -, sense
or
+, -1, -2
or
+1, -1, -2
or
RTD1+, RTD1-, RTD2-