What is a Thermocouple

What is a Thermocouple?

A Thermocouple is a sensor used to measure temperature. Thermocouples consist of two wire legs made from different metals. The wires legs are welded together at one end, creating a junction. This junction is where the temperature is measured. When the junction experiences a change in temperature, a voltage is created. 

Thermocouples are used in many industrial, scientific, and OEM applications. They can be found in nearly all industrial markets: Power Generation, Oil/Gas, Pharmaceutical, Biotech, Cement, Paper & Pulp, etc. Thermocouples are also used in everyday appliances like stoves, furnaces, and toasters.

Thermocouples are typically selected because of their low cost, high temperature limits, wide temperature ranges, and durable nature.

RTD: (Resistance Temperature Detector)

An RTD temperature sensor is a common device for temperature measurements in a wide range of industrial applications. In this article, we take a look at how they work, the most common types, and their advantages and disadvantages.

The acronym “RTD” stands for “Resistance Temperature Detector”. Typically, RTDs contain either platinum, nickel, or copper wires, as these materials have a positive temperature coefficient. This means that a rise in temperature results in an increased resistance – this change of resistance is then used to detect and measure temperature changes.

Platinum RTDs Platinum RTDs are the most common type of RTD used in industrial applications. This is because platinum has excellent corrosion resistance, excellent long-term stability, and measures a wide range of temperature, (-200…+850°C).

Nickel RTDs Nickel RTDs are less expensive than platinum and have good corrosion resistance. However, nickel ages more rapidly over time and loses accuracy at higher temperatures. Nickel is limited to a measurement range of -80…+260°C.

Copper RTDs Copper RTDs have the best resistance to temperature linearity of the three RTD types, and copper is a low-cost material. However, copper oxidizes at higher temperatures. Copper is limited to a measurement range of -200…+260°C.