RTD vs Thermocouple: Which is Better for Your Needs?
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- เผยแพร่เมื่อ 16 พ.ค. 2024
- ▶ Engineer's best friend for learning: realpars.com
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▶ You can read the full post here:
realpars.com/RTD-vs-Thermocouple
⌚Timestamps:
00:00 - Intro
00:59 - Basic Characteristics
06:43 - Advantages and Disadvantages
07:46 - When to Use
08:41 - Real-World Examples
09:06 - Conclusion
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Temperature is an essential measurement for effectively monitoring and controlling various industrial applications.
Incorrect measurements can cause equipment failure, inferior quality of a product, and even severe risks to human health.
For example, controlling the right temperature in the food and beverage industry will ensure the food's quality, flavor, and freshness. If the temperature monitored is not correct, the wrong temperature can lead to health risks for consumers.
Devices are used to measure the temperature accurately, depending on specific applications.
An example of two devices used in industry is Thermocouples (T/C) and Resistance Temperature Detector (RTD).
1) Let’s start by defining the RTD and Thermocouples:
- The RTD can be constructed as a small coil made of a wire wound element as a precise value resistor, mainly around a glass or ceramic bobbin. The winding is generally done in helix or birdcage construction. The RTD is also a passive device.
- The Thermocouple is two different types of metals welded together at one end, creating a junction. The Thermocouple is an active device.
2) What materials are used to make an RTD or Thermocouple sensor?
- For the RTD sensor, the most common elements used are nickel, platinum, or copper wire.
- As for the Thermocouple sensor, different conductive metals will produce different levels of small voltage or charge. The most common types of thermocouples are denoted by a lettering system, such as K, J, T, and E.
3) The RTD and Thermocouple sensors have a measuring range depending on the material type used and the application.
- An RTD can be used in temperatures ranging from -200 degrees Celsius to +850 degrees C.
- The Thermocouple can measure from -250 degrees C to +1800 degrees C.
4) If you need more sensitivity, RTD is a better option.
- RTDs have a slower response time than thermocouples but are more accurate over a wider temperature range.
- In high-temperature applications, thermocouples tend to have a faster response time, but their accuracy can be affected by electromagnetic interference.
5) Here are just a few points to consider before you select the RTD or a Thermocouple,
- RTD can measure lower ranges,
RTD is more accurate,
RTD output is linear.
RTD is more expensive,
RTD is unsuitable for temperatures over +850 degrees Celsius,
RTD has a slower reaction time as related to temperature changes.
- Thermocouple is cheaper than RTD,
Thermocouples can measure a higher range,
Thermocouple reaction time is faster.
The output of the Thermocouple is non-linear,
Thermocouple has poor accuracy,
Thermocouples have poor stability with output results.
6) Here are some factors to consider when choosing a sensor for your control application:
- The measuring range of your application,
- Measurement accuracy you will need from your application,
- The measurement drifts over time of use,
- Single-point measurement narrowed down to the exact spot,
- Sensitivity of the sensor,
- Cost of the sensor.
7) RTD and thermocouples could be found in all types of industrial applications, like the food and beverage industry. They can also be found as close as in your automobile, monitoring the exhaust gas temperature of your tailpipe, engine temperatures sensor, and even your engine oil temperature.
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#RTD #RealPars #thermocouple
Perfect ,Please also explain about PTC and NTC
Thanks for your topic suggestion, I will happily go ahead and share that with our course developers.
Honestly, a comparison between RTDs and Thermistors would he cool even though I already know what it is. Both are resistive sensors, but they have very different applications.
Thanks a lot 😀
My lack is still big in this stuff. Ie : How these sensors are wired to transducer then to tramitter till PLC, Specially if the only power source to them and to PLC as well is within the 24v DC PLC cabinet.
Thank you. A very good refresher content
You're very welcome!
Thanks,
Very informative 🙏
Glad to hear that, Malik!
Best think I have ever used is Platinum RTD with 4-20ma puck then ZERO issues with long wire runs back to chart recorder
I just want to point out that while thermocouple probes might be cheaper than RTDs, usually the electronics required to read a thermocouple, like for example a PLC card or a 4-20 temperature transmitter, can make initial costs higher than the RTD alone.
Or in the world of hobbyists, unless you mess with lookup tables and are a master for calculating cold junction compensations, you're usually better off using a dedicated IC for those. And for electronic components, they can get pricey very quickly.
Thank you for sharing this, we appreciate that!
Little update: you also need electronics to read Read RTDs, but from the few I browsed, they seem to be less expensive than those for thermocouples.However, a veteran in industrial controls can always probe me wrong.
Very well put together video
Thank you very much!
Thanks 🙏🙏🙏🙏
Very nice explanation ❤
Glad you think so!
Thanks very much real pars
You're very welcome!
Thank you very much sir ❤❤❤❤
You're very welcome!
The video is nice, and very well informative. However, there is an inaccurate information on RTD being more long lasting than TC. Because RTD is very small and fragile.
I worked at a place that used both RTDs and thermocouples in conjunction with each other. They had sealing jaws that would melt and press together a plastic bubble of sorts, sealing it and then cutting it. They used the RTD as a heater though, and the thermocouple as the temp sensor. I wasn't sure if that was a common thing in the industry or not? I didn't even know that RTDs could be used as heaters until I saw it there.
Hi there,
Thank you for your question. RTD, as the name implies, it is a resistance temperature detector. It senses temperature and sends a small electrical current to the controller powering it. This signal can control your heater or other devices depending on the engineering design.
@@realpars is this similar to the resistors in heated o2 sensors?
When using a thermocouple. Is the sensitivity to EMC of the cable from the transmitter to the controller more than that of an RTD transmitter?
Is this sensitivity only better the sensor and the transmitter of a T/C?
Should be fine as long as you only ground one side of cable.
thank you very much ❤❤❤ خیلی عالی
Our pleasure, Mehdi!
Make A To Z video about Proximity Sensor (vibration)
Great channel. Very clearly presented information. Subscribed! But, if I understand correctly, thermocouples use RTDs themselves to compensate for the lack of a reference point, right? Then how come RTDs are more expensive? And why use a thermocouple in the first place, when it already incorporates an RTD inside and RTDs are more accurate generally speaking (why not just use that RTD)? Just to widen the temperature range that the RTD on its own would offer, I guess?
Hello Colon05,
Thank you for your question! RTD and Thermocouples are made of different materials, and the RTD is a passive device that needs a power source to be able to work. Thermocouples make up a small electrical voltage when heated due to the metals it’s made of and hook up to an electronic device to measure it. And they both have different data specifications. They are very different depending on the application to be used. And yes, because of the materials used, there is a different price too.
Happy learning!
Brilliant
Thank you!
I'm curious why you said nickel has a high temp coefficient, then said platinum also has a high temp coefficient, but in such a way as if platinum is better? I'm not sure what you are saying the difference is then?
Great question! Both Pt and Ni are good materials for an RTD. Pt has a few advantages: 1) Pt is much more linear than Ni over their operating ranges; 2) Pt gives a much more stable reading over time; 3) Pt has a range of -200C - 850C, while Ni has a range of only -80C to 260C; 4) Pt has better corrosion resistance than Ni. Those are the reasons that Pt 100 RTDs have become an industry standard.
beautiful.
Thank you!
what is electromagnetic interference in Thermocouple??
Thanks for your comment! I will happily go ahead and share that with our course developers as a future topic suggestion.
how to distinguish between these just by looking at when installed in position?
Thank you for your question. Thermocouples only have two leads. On the RTD with three leads, almost always two of the leads will have one color, and the third lead will have another color. For a two-wire RTD, usually, both leads will be of the same color. For a thermocouple, the two leads will always be of different colors. Here is a link to help you with your question.
www.thermalcorporation.com/how-do-you-tell-a-thermocouple-from-and-rtd/#:~:text=Thermocouples%20only%20have%20two%20leads,always%20be%20of%20different%20colors.
Happy learning!
@@realpars thanks a lot
I was taking some ohm readings on an RTD with power still on and the 9 volts from my meter was enough to send a signal to the plc and set off the alarm. Whoops! Rookie mistake 😂😂
Hopefully not the whole plant shut down
@Malik Arthur I don't think there's an RTD in use today outside of Nuclear Reactors that would shut an entire plant down if a warning alarm went off lol.
Sure there isn't,
I was just joking 🙃
Explain pyrometer
Thanks for your topic suggestion, Selva!
good ass video
I think thermocouple is more better than rtd
It depends on the application. For some applications, RTD is better for some thermocouple is better
@@shibajyotimajumder1467 ok..thanks for your information