How Does an RTD Work?

"RTD" is an abbreviation for "Resistance Temperature Detector" An RTD is a type of temperature sensor which can be utilised in the manufacture of Variohms' temperature probe range.

They are available with different temperature / resistance values depending on the application requirement.

How Does an RTD Work?

An RTD consists of a resistance element and insulated copper wires. The most common number of wires is 2; however some RTDs have 3 or 4 wires. The resistive element is the temperature sensing element of the RTD. It is usually platinum because as a material it is highly stable over time, it has a wide temperature range, it offers an almost linear relationship between temperature and resistance and it has a chemical inertness. Nickle or copper are also other popular choices of material for the resistive element. 

An RTD works by using a basic principle; as the temperature of a metal increases, so does the resistance to the flow of electricity. An electrical current is passed through the sensor, the resistance element is used to measure the resistance of the current being passed through it. As the temperature of the resistance element increases the electrical resistance also increases.  The electrical resistance is measured in Ohms. The resistance value can then be converted into temperature based on the characteristics of the element. Typical response time for an RTD is between 0.5 and 5 seconds making them suitable to applications where an immediate response is not required.

Benefits of using RTD Temperature Sensors

RTDs are used within different industries including; automotive, white goods, marine and industrial applications. Benefits of using RTDs over other temperature sensors are;

·         Highly accurate

·         Consistent

·         Offer long term stability

·         High repeatability

·         Suitable for extreme environments

·         Have a high temperature range (depending on resistance element material)  

Types of RTD from Variohm

RTDs are part of our temperature product range, we have the following options

Platinum RTDs – three different temperature ranges available; cryo, medium and high

Nickel RTDs – for applications with temperature ranges from -60C to +200C

Glass Wire Round RTDs – these are well suited to applications in test and measurement

SMD RTDs – for automatic mounting in large volume applications

For more information on our RTD sensor or any of the components we can offer please contact us: 01327 351004 or sales@variohm.com