High-accuracy temperature measurements provide essential data for industrial automation applications to ensure both product quality and safety. Many types of temperature sensors are available， and each one has its advantages and disadvantages. This application note focuses on resistance temperature detectors （RTD）， and explains the design essentials to optimize the measurement accuracy.

　　Resistance Temperature Detectors

　　RTDs contains an element whose resistance changes with temperature. Most elements are either platinum， nickel， or copper. A platinum RTD provides the best performance because platinum has the most linear and repeatable temperature-to-resistance relationship over a large temperature range.

　　Generally， RTDs generate more stable and repeatable outputs， compared to thermocouples and thermistors. Hence， RTDs achieve higher measurement accuracy.