Alberta Boilers Safety Association (ABSA) Practice Test

The principle on which a Resistance Temperature Detector (RTD) operates is that the electrical resistance of certain materials increases with temperature. This relationship allows RTDs to provide accurate temperature measurements. As the temperature rises, the resistance of the material within the RTD increases in a predictable way, making it possible to determine the temperature based on the measured resistance.

The characteristics of the material used in an RTD are crucial; materials like platinum are commonly used because they have a highly linear relationship between resistance and temperature, enabling precise measurements. This property is foundational for the functioning of RTDs in various applications, including industrial processes and HVAC systems.

Understanding that the resistance of RTDs increases with temperature directly supports the operation of these devices and differentiates them from other temperature sensing technologies that might rely on different principles, such as the ones mentioned in the other choices.