VII.5 Sensors

The introduction on sensors has been provided in Module IV. Few types of such sensors will be discussed in the following subsections.

VII.5.1 Temperature Measuring Devices

Most common devices for relatively low temperature measurement are thermocouples and resistance thermometers. Radiation pyrometers are used for high temperature measurements. Other temperature measurement devices are filled system thermometers, bimetal thermometers, oscillating quartz crystals, etc .

VII.5.1.1 Thermocouple

Thermocouples are the most popular temperature sensors. They are inexpensive, interchangeable, have standard connectors and can measure a wide range of temperatures. Their main limitation is accuracy as the system errors of less than 1°C can be difficult to achieve. Following figure represents internal construction of thermocouple and its circuitry.