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5 Dec 2019, 9:16

Common applications for temperature sensors

There is always a need to know whether your system is blowing hot or cold, whether it is for the need to ensure equipment doesn’t overheat or to compensate for temperature-dependent electrical changes. Predicted to top $7 billion by 2023, the temperature sensor market is growing.

There are numerous different types of temperature sensors including thermistors, resistance temperature detectors, thermocouples and infrared sensors. This article will have a look at some applications and how different sensors can be used for them.

The automotive industry and the use of thermistors

In basic form, thermistors are basically resistors whose value depends on temperature. Commonly made of ceramics and nickel, they provide a fast response, are low cost and rugged. Providing a non-linear output, extra circuitry is imperative to generate voltage that is in proportion to temperature.

A common application for thermistors is the automotive industry. They are used to measure the temperature of oil and coolants. They can be used to trigger warning lights which in turn can avoid engine damage.

Accuracy: resistance temperature detector

Like thermistors, Resistance Temperature Detectors (RTD) measure temperature by how it changes their resistance, however, they are made of metal. They have the ability to provide accurate measurements with their linear output.

RTDs are typically more accurate, compared to thermocouples, and are more stable over time. Each component provides the same readings – so a faulty RTDs can be replaced by new parts without the need to recalibrate. In many industrial applications, where long-term reliability and accuracy are essential – this make RTD’s ideal.

Using thermocouples to keep gas safe

Thermocouples are cheap, rugged and can measure temperatures up to 2000 degrees. Based on two different metals touching each other which form two junctions, when one of the junctions is exposed to heat, it produces a voltage – the other junction is kept at a reference temperature.

Often used in ovens and gas-powered boilers, thermocouples are the most popular temperature sensor that is used in industrial applications. They can be used, for example, to sense if a pilot flame is burning.

Infrared sensors

Infrared sensors are often the best choice for non-contact applications. This determines temperature by measuring the infrared energy emitted by an object and converting that into an electrical signal. This is then corrected for the influence of the ambient temperature, 

The medical application is familiar to many of us because of its use in home temperature readers – the ones that are held up in the ear for a couple of seconds. Applications for an infrared sensor vary widely. Not only do they read patient temperatures but can also be used for things like oven temperature in food production.

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5 Dec 2019, 9:16