RTDs (Resistance Temperature Detectors)

More Information about Resistance Temperature Detectors

The precise temperature measurement of an application benefits greatly from the reliable and repeatable nature of resistance temperature detectors (RTDs). An RTD's temperature sensing element—for instance, a wire-wound element—ensures that the temperature measurements delivered are accurate and drift very little, if at all, over time. What's more, common calibration practices guarantee that the temperature characteristics of the detector align with those the application requires. Thus, in applications where temperature measurements need to be right on the money and where a sensor's durability and adaptability in different environments are must-have features, an RTD is often the go-to option.

FAQs

What is the lead wire resistance and temperature coefficient of RTD temperature sensors?

The lead wire resistance of RTD temperature sensors depends on the length and material of the lead wires, which can introduce measurement errors, while the temperature coefficient of RTDs, typically 0.00385 Ω/°C for platinum, defines the rate of resistance change per degree Celsius.

What is the resistance value of RTD sensors?

The resistance value of RTD sensors is typically standardized at 100 ohms (Pt100) or 1000 ohms (Pt1000) at 0°C, with the resistance increasing proportionally to temperature changes based on the sensor's temperature coefficient.

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.