Difference Between RTD and Thermocouple

RTD vs Thermocouple

Heat and temperature form an integral part of our daily life. Sometimes we might think that heat and temperature are the same. Heat is the energy transferred from one body to another, following an irregular moment of atoms or molecules. Temperature describes kinetic or motion energy in a body, along with parameters like specific heat and mass.

According to the International System of Units, the basic measurement of temperature (T) is identified as Kelvin (K). The Kelvin scale is measured at 0k (absolute 0). In this state, molecules have no thermal energy, as the molecules are in a resting state. Since a lower state of energy cannot be achieved, there is no space for negative temperature.

In the famous Celsius scale, which is being widely used by all, water’s solidification point is its zero measure. This is because, in practice, it is easy to reproduce. 0 degrees Celsius is not the last measurement point of temperature with the Celsius scale. The scale measurement can help in tracing the lowest temperature point where there is no movement of molecules.

We require temperature measurement for almost every application, like processing food, controlling building processes, steel manufacturing, petro chemical production, and many more, which are essential for our existence. These applications require sensors using different technology to suit the varied industrial physical structure requirement.

Since the commercial and industrial requirement is different from the control point, the temperature measurement needs to be processed. Resistance Temperature Detectors (RTD) and thermocouples are used to avoid the tedious process of conversion, and get remote electrical signal with ease. The starring difference between RTD and thermocouple is their operation principle and manufacturing.

Resistance Temperature Detectors operate based on the rationale that the impedance of certain metals alters in a certain way based on the temperature fall and rise measurement. The two measurement tools each have their own advantages and disadvantages. RTD provides reliable output over a period. The calibration of RTD outcome is much easier than other measurements. They also offer an accurate reading for narrowed temperature twains.

The few notable disadvantages of RTD is the overall temperature range, which is small, and RTD’s starting cost, which is much higher when compared to thermocouples. RTD’s are fragile, and play tough for rugged industrial usage.

Thermocouple is a thermometer consisting of two wires made from two different metals, which are joined at the end. This will help to generate the different contact point leading to the measurement of temperature. The thermocouple offers a wide range of measurement, ranging between three hundred Fahrenheit and twenty three thousand fahrehheit. The speed of measurement is much faster, and it comes with less investment, and high durability. The thermocouple is best suited for rugged applications.

The notable disadvantage for the use of the thermocouple is the wide range of accuracy, particularly at elevated temperatures. This is also difficult to recalibrate, depending upon the environmental conditions. They might be expensive as long wires are used in the thermocouple.

Summary:

1. The starring difference between RTD and thermocouple is the operation principle and manufacturing.

2. RTD provides reliable output over a period. The calibration of the RTD outcome is much easier than other measurements.

3. Thermocouple offers a wide range of accuracy, particularly at elevated temperatures, making it difficult for a reliable output.

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