RTDs

More Information about Resistance Temperature Detectors

The most prevalent type of resistance temperature detector is the platinum version (Pt100), which has an idealized resistance of 100 ohms at 0 °C. Because they're calibrated to international standards, these sensors can be found in many stringent applications where good temperature control and monitoring are essential. In fact, you'd be hard-pressed to find a better sensor for dependable readings that can withstand not just a few industrial processes but even extreme temperatures (both hot and cold).

What is an RTD?

What is an RTD? 

RTD stands for Resistance Temperature Detector. RTDs use a specific type of metal that, depending on the resistance measured in the metal, can measure temperature. Thin film element RTDs use a very thin layer of resistive metal adhered to a substrate, typically ceramic, and coated in glass or epoxy. Wire wound element RTDs provide greater accuracy and a wider temperature measurement range, however, over time the element wire can become stressed leading to slight measurement errors. Coiled element RTDs are the most common type of RTD and allow for strain free measurement on the wire element while still providing accurate measurement.

How do RTD elements work? 

As the temperature of a metal increases, the metal's resistance to the flow of electricity increases. As the temperature of the RTD resistive element increases, the electrical resistance, measured in ohms, also increases. Each metal has a certain resistance measurement at different temperatures. Based on the resistance that is measured in a given type of metal, it can be determined what the temperature is. The most common types of metals used in RTDs are platinum, nickel and copper. 

What are some advantages and disadvantages of RTDs? 

RTDs provide a high level of accuracy over a wide operating range. Because of their accuracy, they are often used in situations where temperature measurement is critical. RTDs are rarely used at temperatures above 660 degrees Celsius and they do not provide the same level of accuracy or resolution as thermistors at lower temperatures.