Resistance Temperature Detector (RTD)

Resistance temperature detector sensors (RTDs) are used to measure temperature by changing resistance proportional to the temperature. RTD's are designed with basic temperature elements as well as fully packaged assemblies. These so called RTD probes consist of a RTD sensor element, a sheath or housing, an epoxy or filler, extension leads and sometimes a connector or termination. Various sensor materials are available based on customer requirements for material compatibility, accuracy, and measurement range. Standard packages as well as custom designs allow for the flexibility to design the most suitable RTDs for a variety of applications.

While an NTC thermistor is also a resistance device, an RTD is reserved for positive temperature coefficient metal resistance detectors. Typically, RTDs are manufactured with base metals such as platinum, nickel, or copper as these materials have a positive temperature coefficient that is very linear and repeatable. Typical operating temperature range is from -50°C to +600°C but special designs allow usage from -200°C to +1000°C.

TE Connectivity manufactures RTD probes and assemblies, and RTD sensor elements, both platinum thin film as well as glass wire-wound. Platinum (Pt) is the most common material used for RTDs as it has the most stable resistance–temperature relationship over the largest temperature range. To provide interchangeability between manufacturers for the sake of global industry, there are some international standards that have been adopted by most countries including DIN EN 60751 which defines the temperature accuracy and the resistance/temperature characteristic curve for several tolerance classes.

RTD platinum thin film elements from TE Connectivity provide high accuracy and stability, with a wide selection of standard sizes, accuracy classes and are available in both Pt100 and Pt1000 base resistance values to meet the growing industry demand for accurate, stable and reliable platinum sensor elements.

The applications for RTD sensors are extremely broad, including medical, aerospace, automotive, instrumentation, appliances, motor control and HVACR (Heating, Ventilation, Air Conditioning, and Refrigeration). These temperature sensors can operate on board level components as well as in harsh and hazardous locations with various agency approvals. One expanding application for platinum sensor assemblies is for exhaust gas temperature (EGT) measurement. An EGT sensor measures the temperature of the engine exhaust gas to prevent damage to critical components such as the after-treatment system, turbines and cylinder head exhaust valves. An EGT can help optimize engine performance and deliver savings in fuel and maintenance costs.

Figure 1: Various TE Connectivity RTDs.(Image source: TE Connectivity)

Understanding RTDs: Precision Temperature Sensing

When you browse TE Connectivity RTD offerings at DigiKey, you’ll find a rich catalog of many listed products, each tailored for accuracy, stability, and a wide variety of industrial, laboratory, and embedded applications.

What is an RTD, and why choose it?

An RTD is a sensor whose electrical resistance changes with temperature. The following traits make RTDs ideal where precision matters (e.g., process control, HVAC, test rigs, and industrial instrumentation):

• Linearity & predictability — making calibration and compensation easier
• Stability over time — less drift under repeated thermal cycling
• Wide operating ranges — many RTDs span from subzero up to hundreds of degrees Celsius

Popular RTD Platinum (Pt) Lineup by TE Connectivity

There are several popular platinum RTD offered by TE Connectivity:

• NB-PTCO-002 - 100 Ω platinum RTD, resistance tolerance ±0.12% with -50°C ~ 600°C operating temperature and ±0.3°C Accuracy
• NB-PTCO-050 - 1 kΩ platinum RTD, resistance tolerance ±0.06% with -30°C ~ 300°C operating temperature and ±0.15°C Accuracy
• NB-PTCO-006 - 1 kΩ platinum RTD, resistance tolerance ±0.12% with -50°C ~ 600°C operating temperature and ±0.3°C Accuracy
• NB-PTCO-058 - 100 Ω platinum RTD, resistance tolerance ±0.04% with -30°C ~ 200°C operating temperature and ±0.1°C Accuracy

Tips for Picking the Right RTD

When picking the proper RTD for your application, the following guidelines should be followed:

1. Resistance & Tolerance
   A 100 Ω RTD is common (e.g., Pt100). But in certain circuits, 1 kΩ variants reduce lead-wire error. Evaluate tolerance specs to match your design requirements.
2. Operating Temperature Range
   Select parts that cover your expected extremes. TE Connectivity RTDs go as low as –50 °C and as high as 600 °C.
3. Lead and Package Style
   For PCB integration, surface-mount or SIP packages are convenient. For immersion or harsh environments, look into probe or wire-lead types.
4. Excitation Current
   Use low currents to avoid self-heating, but be sure it’s sufficient for signal-to-noise.
5. Calibration and Accuracy
   High-precision systems may need RTDs with tolerances of ±0.04 % or better, versus general-purpose ones at ±0.12 % or ±0.5 %.

RTD Accuracy

Accuracy is a combination of both base resistance tolerance (resistance tolerance at the calibration temperature) and temperature coefficient of resistance tolerance (tolerance in the characteristic slope). Any temperature above or below this temperature will have a wider tolerance band or less accuracy (Figure 2). The most common calibration temperature is 0°C.

Figure 2 : Typical platinum RTD resistance vs. temperature and accuracy curves. (Image source: TE Connectivity)

Summary

At DigiKey, we carry a variety of RTD’s by TE Connectivity, and our parameter search allows you to compare dozens of resistance temperature detectors side by side. By reading the resistance spec, tolerance, operating range, package style, and current rating, you can select the right RTD for rigorous thermal measurement. Whether your design demands high‑accuracy lab instrumentation or rugged industrial sensors, TE Connectivity has options ready to plug into your next project.

Need help choosing the Right RTD?  DigiKey’s TechForum is available to help you find the perfect fit for your application.

Need help with a Temperature Conversion Calculator? DigiKey has several calculators you can use online to help with your next project.

Other Resources:

RTD Platinum Thin Film Product Highlight: https://www.digikey.com/en/product-highlight/t/te-connectivity-measurement-specialties/rtd-platinum-thin-film

TE Datasheet on the Platinum Thin Film: https://www.te.com/usa-en/product-NB-PTCO-006.datasheet.pdf

TE Connectivity RTD Platinum Thin-Film | Datasheet Preview Video: https://www.digikey.com/en/videos/t/te-connectivity-amp/rtd-platinum-thin-film-datasheet-preview

Smarter Solutions Start with TE Connectivity Sensors: https://www.digikey.com/en/product-highlight/t/te-connectivity/sensor-solutions-type

Understanding RTD’s: https://www.te.com/en/products/sensors/temperature-sensors/resources/understanding-rtds.html

Reference:

https://www.te.com/en/products/sensors/temperature-sensors/rtd-sensors.html