The thermocouple is a device that converts thermal energy into electrical energy.
DESCRIBE the basic construction of a thermocouple
Major component arrangement
EXPLAIN how a thermocouple provides an output
representative of the measured temperature.
Figure 4 Thermocouple Material Characteristics
When Used with Platinum
A thermocouple is constructed of
two dissimilar metal wires joined
at one end. When one end of each
wire is connected to a measuring
becomes a sensitive and highly
Thermocouples may be constructed
of several different combinations
of materials. The performance of
generally determined by using that
material with platinum. The most
important factor to be considered
when selecting a pair of materials
is the "thermoelectric difference"
between the two materials.
significant difference between the
two materials will result in better
thermocouple performance. Figure 4 illustrates the characteristics of the more commonly used
materials when used with platinum.
Other materials may be used in addition to those shown in Figure 4. For example: Chromel-
Constantan is excellent for temperatures up to 2000°F; Nickel/Nickel-Molybdenum sometimes
replaces Chromel-Alumel; and Tungsten-Rhenium is used for temperatures up to 5000°F. Some
combinations used for specialized applications are Chromel-White Gold, Molybdenum-Tungsten,
Tungsten-Iridium, and Iridium/Iridium-Rhodium.