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
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IC-01
