RTD | Resistance Temperature Detector

In this lecture, we are going to learn about the RTD (Resistance Temperature Detector) in very brief. we will learn about the equation for the measurement of RTD’s resistance. SO let’s discuss the topic.

RTD (Resistance Temperature Detector)

The resistance of a conductor changes when its temperature is changed. This property is utilized for the measurement of temperature.

RTD is a temperature-sensitive device that has a positive temperature coefficient.

They are composed of metals such as platinum, nickel alloy, and copper. Platinium is the most common material because it is stable at high temperatures.

RTD can be used for the temperature range from -218oC to 630oC.

The variation of resistance ‘R’ with temperature T (oK) can be represented by the following relationship for most of the metals:

R=R_0(1+\alpha_1T+\alpha_2T^2+….+\alpha_n T^n+…)

where, R0= resistance at temperature (T=0) and, \alpha_1,\alpha_2,\alpha_3....\alpha_n are constants.


The resistance thermometer uses the change in the electrical resistance of the conductor to determine the temperature. The equation shows that its characteristics are non-linear. but it can be linearized by neglecting the other higher order terms,

\boxed{R_{T_2}=R_{T_1}(1+\alpha \Delta T)}

Where, \Delta T=T_2-T_1

Frequently Asked Questions on RTD

  1. What are RTD sensors?

    Answer: RTDs – or Resistance Temperature Detectors – are temperature sensors that contain a resistor that changes resistance value as its temperature changes.

  2. What is an RTD used for?

    Answer: The resistance temperature detector (RTD), is a thin film device made of platinum, which is used for measuring temperature. It has great stability, accuracy and repeatability. The resistance tends to be almost linear with temperature – the higher the temperature, the larger the resistance.

  3. What are types of RTD?

    Answer: What types of RTDs are available? There are two main types of resistance temperature detectors, thin-film, and wire-wound.

  4. What are the advantages of RTD?

    Answer: The major advantages that an RTD has over Thermocouples are: Stability, Precision, and Repeatability. 

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Hello friends, my name is Trupal Bhavsar, I am the Writer and Founder of this blog. I am Electronics Engineer(2014 pass out), Currently working as Junior Telecom Officer(B.S.N.L.) also I do Project Development, PCB designing and Teaching of Electronics Subjects.

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