Pt100 Sensor Explained | Working Principles
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- Опубликовано: 1 июл 2024
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⌚Timestamps:
00:00 - Intro
00:50 - What is a Pt100?
01:37 - Physical properties of Pt
02:30 - Alpha coefficient
04:29 - Industrial Pt100
05:38 - 2-wire Pt100
06:17 - 3-wire Pt100
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Platinum 100, or Pt100 RTDs are an important part of many process control installations.
RTDs are a class of sensors that change resistance when the temperature of the medium they are inserted into changes.
This change of resistance is proportional to temperature and varies in a somewhat linear fashion with temperature.
It is due entirely to the physical properties of the material from which the RTD is constructed. While RTDs can be manufactured from many metals, including nickel and copper, platinum exhibits physical properties that make it ideal for use in RTD temperature sensors.
1) Platinum is a basic element, with the chemical symbol, Pt. That is the first part of the designation of the Pt100 RTD. Platinum has a molecular weight of 195, which makes it a rather heavy metal with free electrons to make it a good conductor of electricity, although not as good as copper or silver.
2) Platinum exhibits an electrical resistance that varies in a nearly linear fashion with temperature and has a resistance of exactly 100.00 ohms at zero degrees Celsius. This is where the second part of the designation Pt100 comes from.
3) Another property of platinum that makes it highly valuable to temperature measurement is that it is quite inert. It does not react with other compounds to any great extent.
The most common Pt100 RTD used in industry is one that changes resistance at the rate of about 0.385 ohms for every degree Celsius rise in temperature.
The “385” factor comes from the equation that approximates the resistance of an RTD based on its physical properties.
The equation relates the resistance of the RTD at the temperature being measured to the resistance at zero degrees Celsius. The coefficient alpha in this equation describes the rate of change of resistance with temperature.
The Pt100 RTD is often referred to as the Pt100 (385) RTD. There are platinum RTD’s that exhibit different values of alpha, and those would be designated with their respective alpha values, such as with the Pt100 (391) sensor.
The equation is only approximate, so to know the true temperature at any measured resistance, we will need to consult a published standard table of resistance for a Pt100 (385) sensor. You can find the link to this table here: bit.ly/Pt100RTD385
A Pt100 RTD is typically constructed by winding a thin platinum wire around a non-conductive core which helps support the thin wire. The entire assembly is encased in a sheath to protect the sensor and to give it stability.
In industrial applications, RTDs are commonly placed inside protective metal tubes called thermowell. The length of the RTD and the design of the thermowell are design parameters determined by the instrument engineer.
PT100 RTDs can be constructed from a single platinum wire, giving a sensor with two leads.
These leads can be connected to a special I/O card designed to accept RTD inputs, or the leads can be connected to a temperature transmitter, which will output a standard 4-20 mA signal.
In order to determine the resistance of the RTD, a special bridge circuit is used, called a Wheatstone bridge.
This 2-wire RTD design is not very accurate because the platinum leads themselves have an electrical resistance due to the length of the wire and the connection points, in addition to the resistance from the temperature detected at the point of measurement.
To compensate for this added resistance, a second platinum wire is added to the sensor at a third lead. This third lead is used to determine the resistance of the lead itself, and the resistance is subtracted from the overall measure resistance to give the true resistance due to the change in temperature alone.
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#RealPars #Pt100 #temperature_sensor
RealPars is light-years ahead of everyone else in terms of explanation, presentation, and slick editing. I'm taking beginner electronics courses and it's just so satisfying to be able to (somewhat) keep up with these videos! Thank you to the good folks @ RealPars!!!!
Great to hear!
I just want to thank real pars for detailed and wonderful presentation, hoping for more series on other temp measuring elements like thermocouple .
Thank you very much!
Another great video. I work with RTDs on a Mitsubishi Q series PLC, and have just learned now that Pt refers to the metal platinum! Also the explanation for why they have 3 wires and why they have the "100" designation! Brilliant, clear and well-explained video. Also the recap at the end is excellent.
Thanks for sharing that!
I'm actually in awe of how excellent your videos are. Thank you!!
You're very welcome!
Never looked at RTDs that way, things are more meaningful and more reasonable to understand now.
Excellent work as usual.
Thanks a lot!
More videos like this please. Excellent information, would love you to hit on something that I haven’t been given the dirty details of yet.
Thank a lot. We need explanation for thermocouple
They already did one a few years ago. Check it out here:
ruclips.net/video/4mQ3o1t4Ssg/видео.html
Wow, Great instruction!
Thanks for making these meaningful and animated videos. With these visual presentations for understanding things in detail and delving deeper into the concepts, everything will be better.
Best Regards
Glad you enjoyed it!
Let's first appreciate how well this vedios is animated and presented... So eye joyful picture... Keep it up
Respect from Africa sudan
Thanks a lot, Hamza!
Thanks a lot to Real Pars for sharing perfect and scientific knowledge on Pt.100 sensors ,
this video is greatly useful for new learners, Thank you .
Glad to hear that, Prashant!
I was looking for a video like this 1 year ago since i had a project about it.. Cant believe you made it now
Glad to hear that, Gonzalo! Happy learning
This is gold - I mean platinum, of course ;)
Thank you for sharing this well made video with the world!
Glad you enjoyed it! Thanks for your support!
Thank you very much RealPars. Your videos greatly help me.
Glad you like them, Adrian!
It is a excellent video and I just love the way you present it. Hoping for more videos from you.
Thank you so much!
Once I get a job I will buy your membership...
Thanks for the introduction!
Our pleasure!
Thanks I added this to my work notes
Glad it was helpful!
thank so much, this video will help me a lot in my project graduation
Glad to hear that!
Again its time to thanks team realpars... For excellent explained the PT100 whole topic.. what about next videos on,, PT 385
You're more than welcome!
perfect video and this channel is so useful for knowledge
Many thanks!
Very unique video... it takes me back on time to campus 10 years ago.but I Didn't knew about that it should be made of platinum. ..
Thanks for your support!
Bhot pyara samjha hai ❤ love from india ❤
Very nice and informative video, thank you!
Glad it was helpful!
Thank you again, interesting video!
Glad you enjoyed it!
Thank you for sharing information
Our pleasure!
Just keep posting more videos! I love 💘 your videos!
Thank you so much!
Tnx for all
Excellent explanation.
Thank you, Siddharth!
nicely explain whole concept of pt100 thanks a lot.
You are most welcome! Happy learning
Great product.
Very interesting video...thank you again
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thank you sooooooooooooooooooooooooooooooooooooooo much for this wonderful videos love you guys(All the team)
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BIG Thank you 😊
You're welcome!
Very informative 👏thank you
Glad it was helpful!
Great job well presented.
Thank you!
Interested to learn, nice explanation.
Glad to hear that! Happy learning
Awesome video 🔥🔥🔥
Glad you liked it!
Thanks, very informative video
You're welcome!
Great job, thanks for excelent explaned video about PT100, keep working. Can you make videos about relay protection ?
Hey!
Thanks for your comment and your suggestion. I will pass this on to our course developers!
Thanks for sharing and happy learning!
Thank u so much really
Wish u can explain the J type and how its able to work in heat and cooling aswell
J type is a type of thermocouple.
Thermocouples differ from RTDs drastically. Where temp. changes alter resistance in RTDs, temp changes alter the voltage generated by thermocouples. The voltage generated is very minimal (think mV ranges) but linear in its change across the range of temps. This is due to the compositons of the 2 metals of the wires in a thermocouple. They are 2 dissimilar metals joined together. Which brings us to the type you mentioned...There are a multitude of thermocouple types... j, k, t, r, s, etc. And these designations define the types of metals used in the wires. The different types have differing ranges of optimal use. But j and k types seem to be industrial standards for general purpose.
Lastly I'd say thermocouples could be cheaper but for the most part less accurate than rtds.... this isn't always true, just generally.
Anyway I hope this helps
very informative ‼️
Glad you think so!
Thansk alot Sir, need thermocouple video also
Thank you, Pandu! Will happily pass this on to our course developers.
Great video thank you
Glad it was helpful!
Perfect realpars 😍
Thank you!
Excellent video...
Thank you!
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great video! thanks!
Glad you liked it!
Sir, Thanks for information.
You're very welcome, Shivaji!
thanks
Nice explanation 👍👍👍
Thank you!
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Thank you!
thank you
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great video
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Most welcome!
During job interviews, i got questions about Pt100 a lot. 2 wires versus 3 wires and even 4 wires, benefits from it, etc.
Thanks real pars. Could you please explain about f and g detectors.
Hi Mohammed,
Thanks for the topic suggestion, I will definitely go ahead and forward this to our creator team.
Happy learning!
Good information ❤❤🌹🌹
Thank Sir
Great video as always by Realparse. I have a question with the resistance table please. What does the row “ 0,1,2,…” symbolizes?
I understand the column beneath the degree Celsius symbolizes temperature but I do not understand the row section
That row is actually column headers representing tenths of a degree. So under the 2 column, the value in the row labelled 30C indicates the resistance value for 30.2C.
Question...should the Pt100 RTD be connected directly to the PLC I/O module or can it be wired to an intermediate junction box? Then from the junction box to the PLC on e.g. 3 copper wires?
An RTD should be connected directly to a Temperature transmitter or it can be connected to a terminal block and then run to the PLC. If you use copper wires to run the RTD signal to the PLC, make sure you use a single cable with 3 conductors. This helps insure the resistance on all three wires from the terminal block to the PLC card are as close to being the same as possible.
Excellent info RealPars. We have an RTD that keeps failing. It's installed horizontally in a 3" "T" it keeps breaking near the coupler. Not sure why. Any suggestions?
Strain relief at the coupler. It sounds like there is some tension on the coupling and the wire is being stressed. The platinum wires of an RTD are relatively fragile, so you need to insure there is no strain on the wire or coupling. Try looping the cable before it enters the "T" and support the loop to a bracket or piece of strut so that there is no strain on the wire. Or, install a junction box near the RTD, so that there is nothing pulling on the leads near the instrument. Remember, if you do this, you will need to use special terminal blocks and extension wire compatible with the type of RTD you are using. Also, Pt is a metal, so it will expand and contract with temperature.
hey! could you elaborate a bit about the datasheet in the video? what does -9 - 10 stand for? many thanks.
The temperature versus resistance chart indicates the exact resistance of the Pt100 RTD at the indicated temperatures. the numbers across the middle of the chart indicate the readings at the temperatures between the temperatures on the left and right (...30, 20, 10, 0, -10, -20, -30....). So in the -10 C row, the column above -1 n the blue shaded row indicates the resistance at -11C, above the -2 row, -12 C, above the -3 row, -13 C, etc.
Amazing
Thank you!
At times I wonder what those dislikes are all about after listening to this beautiful presentation 🤔
Can you please make a video on BMS Systems?
I want to start career as BMS engineer, what should i learn or work with? Thanks in advance
Hey!
Thanks for your comment and your suggestion. I will pass this on to our course developers!
Thanks for sharing and happy learning!
Good video. Thanks.
How about pt1000 compared to 100? Biggest difference and advantages disadvantages?
Great suggestion! I will pass this on to our course developers for a possible future video course.
@@realpars thank alot
Dear sir,
As you know, the temperature sensor (RTD PT100) has a specific range (e.g. -200 to 850 ˚C). This sensor transfer temperature to Ohms. That is why it is connected to a temperature transmitter which transfers Ohms into (0-10 V or 4-20 mA) to be able to connect with the PLC. Transmitters also have a specific range (e.g. 0-200 ˚C).
My question is since Temperature sensors and Transmitters have got different range, are there certain conditions to fulfil when connections them (like calibration) , would you kindly answer my question? Of course, practical examples are of great importance to me.
Thank you and I’m waiting for you reply.
RTD measurements are based on the physical properties of the RTD material, like Pt100. There is no calibration required. The transmitter URL and LRL are set to suit the needs of the application, but there is no additional configuration required beyond telling the transmitter that a 3-wire Pt 100 sensor is connected. If a different type of sensor is to be connected, the proper selections are made and the transmitter does the rest.
Nice..
Super
you are genius
Thank you!
1. What is the maximum distance from the RTD to the special RTD IO card?
2. Does RTD with transmitter require a separate power supply
1. 250 meters would be about the max for 20AWG wires. any longer, and the wire resistance will become significant. Use a transmitter at the location of the RTD, and the 4-20ma current loop can be run up to about 1000 meters. Obviously, you will need a different card at the PLC (Analog Input instead of an RTD card).
2. No, RTD Temperature transmitters can be loop powered (by the analog input card).
@@realpars 250 meters range is for 2 wire RTD or 3 wire RTD? Can you tell me the maximum distance that a 3wire RTD can send signals to DCS or PLC without a transmitter?
Dear sir can you explain about ac and dc servi amplifier (drives).
Thanks for the topic suggestion, I will definitely go ahead and forward this to our creator team. Happy learning!
Thank you sir.
Please explain the wheatstone bridge circuit for 2 wire and 3 wire RTD Pt100 in a separate video.
Thanks for your topic suggestion, I will happily go ahead and pass that along to our course developers.
Thank you for the video! I have few questions. Is it ok to bend the pt100 core? What happens if for example, I have to measure the temperature with the tip of the sensor, but along it's length it has contact with some other parts? Does it affect on the measurements? Thank you in advance.
It is best to not bend an RTD probe, as it is typically constructed with an insulating material around the mandrel and lead wires. If the insulating layer is damaged, it can affect the RTD circuit (short circuit, grounded to sheath, etc.). The bulk of platinum wire is concentrated at the tip of the probe (mandrel) and preferentially will measure the temperature at that location. However, the part of the probe not submerged in the fluid can slightly affect the temperature reading, so RTD probes should be specified at the appropriate length to minimize measurement error.
Hello ,
Can someone please explain how did we get this equation? Rtotal=Rl1+Rl2+Rtd-(Rl2+Rl3)
Thank you ,
Best regards to the team!
The total resistance between R1 and R2 is the sum of the resistances, or (RL1 + RL2 + RTD). Since the wires themselves have a resistance (RL1 and RL2), the total resistance between R1 and R2 is overstated. We need to subtract out the lead resistances, which, in a Wheatstone Bridge, is accomplished by subtracting out the resistance between RL2 and RL3. Therefore, we are left with Resistance = (RL1 + RL2 + RTD) - (RL2 + RL3) = RTD + RL1. From this analysis, it is clear that the true temperature reading is biased only by the lead resistance in Lead #1 (RL1), which should be a very small amount. A four-wire RTD configuration eliminates lead resistance bias, but in a different manner.
@@realpars I understood. We add one more wire to balance the losses.
How I can connect single RTD signal with parallel, so I can use RTD signal for two different devices
You can't. An RTD cannot be wired in parallel or in series to a second device. An RTD input supplies a known, regulated ‘excitation’ current to the RTD. Mixing RTD inputs would mix currents, leading to very inaccurate measurements. You can use an RTD transmitter and an analog signal splitter to provide a signal to two separate devices, such as a PLC.
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is it possible to have courses for us French speakers on the site
Hi Tangara,
Thanks for your comment! We currently only provide our course videos in English, you are always able to turn on the English subtitles as that might make it a bit easier for you.
Our apologies for any inconvenience!
Happy learning!
@@realpars Merci à vous
The Engineering education would be 2 years instead of 4 if the courses were like your videos
Amazing compliment! Thanks a lot!
Cool
how can I thank you.
hello . Can I share this videos in persion langugae?
Hi Abbas,
Thanks for your comment!
Our company policy does not allow third parties to translate and re-upload our video courses. We are more than happy to add Farsi subtitles to our video courses, you can send the Farsi subtitle files to us, and we will happily add those for you.
Hope this helps!
👍👍👍
Thermocouple explanation please
Thanks for the topic suggestion, I will definitely go ahead and forward this to our creator team. Happy learning!
Pt100 is a sensor o transmitter ?
Pt100 is a type of RTD (Platinum 100-ohm resistance at 0C). An RTD is a sensor, so to answer your question, a Pt100 RTD is a sensor. RTD's can be connected to a transmitter to make it easier to deliver the measured temperature to the PLC or DCS analog input card.
Superrrrrr
Thank you, Mahmut!
good
Loose wiring in RTD any CAPA
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