Thermocouple vs RTD. Differences and How Temperature Sensors Work
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- čas přidán 4. 08. 2024
- Thermocouples and RTD are two methods of measuring temperature yet the work on two different principles. A thermocouple connects two different types of metal together and these will output a specific voltage depending on the temperature. An RTD sensor uses a single metal such as platinum and the resistance changes based off of the temperature. Additionally RTD sensors will be 2, 3, and 4 wire varieties and that will affects their accuracy. We didn't include thermistors in this but both thermistors and RTDs measure resistance. The RTD uses precious metals whereas thermistors use semiconductor materials.
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Something to pay attention to is that when using a thermocouple the extended wiring if needed must be thermocouple wires. Another important item, which has been debated, is any connection termination should be done with a thermocouple compatible junction. This means no crimp-on eyes, spades or forks.
Why; each termination can introduce dissimilar metals which can introduce a error in the voltage value. These thermo devices certainly deserve a short study to understand them. Great introduction Tim.
Yes, the thermocouple extension wire and connectors are important. Thanks for watching!
Excellent description of the two types of temp measuring probes!
Glad it was helpful!
Great video Tim, Thank you!
Glad it was helpful!
really love to watch this super practical and demonstrative lesson!
Happy to hear that!
I recently had this question pop up on a self test. I always thought it was resistance that causes the feedback. When I told my master electrician that it is DC voltage, he didn't believe me. I learned something that day, as did he.. and I'm glad to see you covering it, too. I'll be sure to share this video with the rest of the automation guys that I work with. :)
Share it often Eric! One interesting idea I have always had is it is based off of heat and dissimilar metals exchanging electrons. I should be able to feed electricity into a thermocouple cool a thermocouple tip. It is on my list for a day of crazy experiments.
@@TimWilborne that is really interesting. I might have to remove one from an older piece of equipment at work and play around with that. Could be really cool (pun intended) 😜
@@sirkus34 🤣
Very timely video, thanks Tim!
Glad it was helpful!
Wow so good
Thank you 😋
BTW Allen-Bradley and other manufactures offer thermocouple/mV to analog conversion cards for Thermocouple use.
Have a video coming on that.
I am definitely going to watch that one. I was working on this card today. I was not sure how to test the RTD I/O card to make sure is working properly. Also I had a fault on a open RTD, when I check the RTD 112 ohm with no issue. Change the RTD anyway and machine start working properly. Not sure what I am missing? Any tips for new tech?
Nice Insight Tim!, btw i am confused which sensor (RTD or thermocouple) should i Choose for Water treatment plant. The range should be around normal temperature to 80C. and for the ph of the water is vary from 5 - 12. Can you suggest? Thank You very much !
No, you would be better off reaching out to a sensor distributor.
In general, RTD is much more expensive but it is also more accurate and since they are usually made from materials of higher precision, they are often more durable.
Check out the Omega line, they cover the range of Temperature Measurements.
hI Tim, I know I bug you alot. But could you tell me what all I need to make a homemade PID trainer? I have the PLC, I just need whatever else. I am sure I need a thermocouple and some type of heating element to connect to output of plc. Just tell me what I need and I'll order it from you. In my head I am picturing a stock pot of water with a heating element between that and the PLC, along with the thermocouple going back to plc. Am I on the right track? BTW a I am using a micrologix 1100 using micro starter light. But I could use studio 5000 on my work PC
I'm not sure that would be a good learning tool. I think the question is, how in depth do you want to get into PIDs?
@@TimWilborne I'm a controls Tech and I see PID programs all the time. If I can simulate a program and see it working, that's how I gain an understanding of it. In my head, I was picturing programming the PID in RSLogix, Studio 5k, etc., and then actually connecting something to my PLC and watch it work.
Please please demonstrate how to wire these into the compact logix when you do the next video! Please don't already have it wired in. I'm having so much trouble finding information on how to wire these things in correctly!
Here you go Steven.
twcontrols.com/lessons/configuring-compactlogix-universal-inputs-for-rtd-temperature-sensors
Rather see how to tell if they are accurate?