RTD Installation and Maintenance 101: A Beginner's Guide

▶ Engineer's best friend for learning: realpars.com
============================
▶ You can read the full post here:
realpars.com/rtd-installation...
⌚Timestamps:
00:00 - Intro
00:21 - How does an RTD work?
01:08 - How RTDs are Used?
04:13 - 2, 3, and 4-wire RTD
05:11 - RTD Protection
06:14 - RTD maintenance and troubleshooting
07:28 - Summary
=============================
In this video, we're going to introduce you to the Resistance Temperature Detector commonly referred to as RTD.
We’ll talk about how the RTD works and how it’s used in industry to measure temperature. We’re also going to discuss regular maintenance, calibration, and troubleshooting of RTD circuits.
An RTD is a passive resistive device made from a metal that changes resistance with a temperature change. If the temperature increases, the RTD resistance increases.
In most applications, a current is passed through an RTD to determine temperature. Using the resulting voltage across it, the RTD resistance can be determined using Ohm’s Law.
The resistance changes almost linearly with a temperature change. A very good linear range for the Pt100 RTD is 0 ℃ to 400 ℃.
The relationship between temperature and resistance of an RTD is referred to as the temperature coefficient (Alpha). The Alpha of a Pt100 RTD is 0.00385 ohms/ohm/℃.
The Wheatstone Bridge was probably the most commonly used method originally. But, it's not so common anymore. The distance between the RTD and the bridge becomes an issue because of the introduction of lead wire resistance.
The Constant Current Source method is very popular. The voltage is a direct result of the resistance of the Pt100 and the constant current flowing through it.
An increase in lead wire resistance does not affect the Voltage V because the current through the RTD is not affected.
You will rarely see a 2-wire RTD used in an industrial application because of its inherent problems with resistance detection.
3-wire and 4-wire RTDs are the industry standards as issues with lead wire resistance are eliminated.
Probably the best and most accurate temperature measurement is made using a 4-wire RTD connected to a Constant Current Source transmitter.
The transmitter current is unaffected by the lead wire length. The voltage resulting from the constant current and the RTD temperature is detected by the transmitter.
The transmitter converts this detected voltage and sends a corresponding signal to a receiving instrument such as a PLC.
An RTD needs protection. A connection head is used to connect the RTD leads to the transmitter. The connection head also protects from nasty ambient conditions.
Further protection is provided by inserting the RTD sheath into a thermowell that is permanently housed in a pipe or a vessel. The thermowell protects from potentially damaging process fluids.
The RTD can be easily removed from the thermowell without interrupting the process.
Thermowells create issues such as a delay in detecting process temperature changes. Thermowell placement is also an important consideration.
A defective RTD will cause issues as well. You can perform a very quick and simple test by isolating the RTD and connecting an ohmmeter across it. The RTD will read a finite resistance value of approximately 110 ohms to 115 ohms depending on the ambient temperature.
The best way to isolate the problem is by using a process calibrator to replace the RTD in the measurement circuit.
The process calibrator can simulate the RTD by producing resistance and applying that resistance to the transmitter.
=============================
What is an Instrument Calibrator?: realpars.com/instrument-calib...
If you want to become an RTD expert, then our free course is perfect for you. Get all the tips and tricks on how to install & troubleshoot these devices like a pro.
Complete Introduction to RTDs: learn.realpars.com/courses/in...
=============================
Did you miss out on the latest and greatest? Catch up now by watching our videos right here:
realpars.com/s7-1200-plc-Intr...
realpars.com/profinet-etherne...
realpars.com/RTD-vs-Thermocouple
=============================
Ready to stay on the cutting edge of our newest video content? Be sure to hit subscribe and join us on this exciting KZbin channel!
bit.ly/realpars
=============================
TWEET THIS VIDEO: ctt.ac/q1oWu
=============================
Follow us on Facebook 👉 / therealpars
Follow us on Twitter 👉 / realpars
Follow us on LinkedIn 👉 / realpars
Follow us on Instagram 👉 / realparsdotcom
#RealPars #RTD #instrumentation

[@khanyithegreat]

Real pars never fails. Great video.

[@realpars]

Thank you!

[@Rahul-uv4pz]

Very informative video 👏👏....And very close to 1M subscribers, hope you guys achieve this soon

[@realpars]

Thank you for your support, Rahul!

[@JC-sc9rx]

Now thermistors in our outdoor air cooled chiller units provide a similar function to detect entering and leaving water temps however the opposite is true. The higher the temperature the lower the resistance measured in K ohms. Lower the temperature the higher the resistance. Good video though just thought I would share a similar apparatus and how it reacts to temps

[@DanielAlor1]

Thank you so much sir

[@realpars]

You're very welcome!

[@ricardogarcia3900]

A good video ... Always

[@realpars]

Thank you, Ricardo!

[@AnasAl-Dhafiri]

Thank you very much

[@realpars]

Our pleasure!

[@reubenhlatshwayo9621]

Good content

[@realpars]

Thank you!

[@basilrasool]

Good

[@adrabie733]

Good❤

[@rhomis]

I have an RTD that's 13 foot long (large coil with nut and ferrule). How do you install that into a heat exchanger?

[@realpars]

Hi there..... Thanks for your question. Can I ask you a few questions first? Is the RTD thermowell already in place? What is the RTD connected to? A temperature transmitter> A PLC input card?

[@rhomis]

@@realpars - The RTD is no longer installed. Somebody pulled it out and ruined it. It was connected to a Rosemount transmitter. Has two RTD sensors. There is only 6 inches of gap to install it in position. Otherwise the entire heat exchanger will have to be isolated and disassembled on the next shut down. There are a total of 4 Rosemount transmitters on this heat exchanger, each having a dual element, and different lengths. The Puck inside the Rosemount transmitter sends a 4-20ma signal to a CHARMS cabinet (no PLC board).

[@jorgedaza4799]

👏👏👏👏👏👏

[@gregntammie]

I absolutely hate the RTDs and TCs with pecker head terminations. Pain in the ass to work with. We have replaced all of ours over the years with armor flexed TCs and RTDs using bored thu tubing fittings.. They should make engineers work on this shit upside down, in the heat, covered in grease and hotter than hell before they spec this shit. The only time I have ever had anything where you can walk right up to it and work on it comfortably is when another technician has engineered and installed it.

[@PORRFNK]

Never had any issues with high quality RTD's in my 15 years working with them. The video doesnt really say how bad a thernowell is for reaction time

[@punjab4816]

thank you so much sir 🌹🤍🙏

[@realpars]

You're very welcome!