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.
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 😂😂
@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.
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.
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.
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.
Thank you for your question. This is a good question, but it’s difficult to answer. It is hard to say without seeing your specifications, applications, and engineering setup. As we explained in our video, these devices have different temp and power setups. The RTD will give the most accurate reading. But either one you use, you must set it up correctly as in the specs and user manual. Here is a link for your learning. www.omega.com/en-us/temperature-measurement/c/temperature-probes
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.
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.
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.
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!
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?
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!
