RESISTANCE TEMPERATURE DETECTORS (RTDs)

Temperature Detectors RESISTANCE TEMPERATURE DETECTORS (RTDs) RESISTANCE TEMPERATURE DETECTORS (RTDs) The resistance of certain metals will change as temperature changes. This characteristic is the basis for the operation of an RTD. EO 1.1 DESCRIBE the construction of a basic RTD including: a. Major component arrangement b. Materials used EO 1.2 EXPLAIN how RTD resistance varies for the following: a. An increase in temperature b. A decrease in temperature EO 1.3 EXPLAIN how an RTD provides an output representative of the measured temperature. Temperature The hotness or coldness of a piece of plastic, wood, metal, or other material depends upon the molecular activity of the material. Kinetic energy is a measure of the activity of the atoms which make up the molecules of any material. Therefore, temperature is a measure of the kinetic energy of the material in question. Whether you want to know the temperature of the surrounding air, the water cooling a car’s engine, or the components of a nuclear facility, you must have some means to measure the kinetic energy of the material. Most temperature measuring devices use the energy of the material or system they are monitoring to raise (or lower) the kinetic energy of the device. A normal household thermometer is one example. The mercury, or other liquid, in the bulb of the thermometer expands as its kinetic energy is raised. By observing how far the liquid rises in the tube, you can tell the temperature of the measured object. Because temperature is one of the most important parameters of a material, many instruments have been developed to measure it. One type of detector used is the resistance temperature detector (RTD). The RTD is used at many DOE nuclear facilities to measure temperatures of the process or materials being monitored. Rev. 0 Page 1 IC-01