RTD Type

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phatmatt

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Thermocouples have color codes. J type red and white K type red and yellow etc..

Are there color code standards for RTD's?

At work (Im still an apprentice) I run into metal clad RTD probes frequently and aside from looking at the transmitter and what it is programmed for I have no idea what type of RTD I am looking at.

When I asked at work someone said there was a wire color standard for RTD's just like thermocouples but I havent been able to find one.

Any information/advice would be greatly appreciated.
 
I don't think I have seen any colors other than red and white for the leads of a single element RTD. I am not aware of any color code standard.
A quick look at Omega's technical reference section does not show any colors for RTD types, but it was only a quick look and it could be there somewhere.
 
don_resqcapt19 said:
I don't think I have seen any colors other than red and white for the leads of a single element RTD. I am not aware of any color code standard.
A quick look at Omega's technical reference section does not show any colors for RTD types, but it was only a quick look and it could be there somewhere.
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There is no standard that I know of, and we get 3 wire 100 ohm platinum RTD in White/Red/Red, Yellow/Red/Red, White/White/Red, etc.

We put the color codes on the wiring diagrams, so the color code is sometimes wrong. So we put functional names on the Terminal Block so they get wired correctly, like T+, T-, T-.
 
That's crazy. I would think there was some type of standardization.

So when I go up to a process and pull the Rtd probe, which is the best way to determine whether I have a platinum, copper, any variation of the two or one of the many other types?

I could always put in a type that is available and re program the transmitter, but that may cause a ton of paperwork and delay due to the fact that its not a replacement in kind.

I guess I could always check the loop drawing. But what a hassle.

Thanks for your input guys. I was just trying to learn a little and make my job easier. Guess there is no simple solution.

Have a great day!
 
Check the resistance with an Ohmeter. 10 ohms = copper. 100 ohms = platinum. (I can't remember a nickel unit's standard resistance). The other difference is 4-wire, 3-wire or 2 wire elements. Most installations use a three wire. If the circuit transducer uses a two-wire RTD, install a 3-wire just use the two wires that have the resistance between them.
 
thanks all

yeah... most of our rtd installations are 3 wire pt100 but when I was checking calibration on one yesterday I shot 75f to the transmitter I got like 268 or something crazy like that. It took me a while to finally look at the transmitter programming (mostly because it was a super old varec transmitter and couldnt find a manual) to find out it was set for copper.. shot a 75 copper and it was fine.


I guess next time I can just check the resistance if there is a question about what type of rtd it is. that seems easiest.

Thanks again.
 
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