TC temperature measurement

Thermocouple types
The Seebeck effect, which is made use of for TCs, states that a voltage is generated when two dissimilar metals are joined together. The voltage generated can then be measured and converted into temperature readings, using a calibration curve or table. There are different types of thermocouples, based on different wire pairs and measuring ranges. Each type of TC has a unique relationship between the voltage generated and the temperature. The type can be identified by an assigned letter, e.g. TC type K, type J or type T.

RTD vs. TC – a comparison
Their main difference is the temperature range, as an RTD can be used in moderate temperatures ranging from -200°C (300°F) to +850°C (1562°F). The Thermocouple sensor can measure from -270°C (454°F) to +1820°C (3308°F). In general, the choice between a TC and an RTD thermometer depends on the specific requirements of the application.

What are RTDs used for? If you need higher accuracy or are measuring lower temperatures, an RTD may be the right choice. They have a slower response time than thermocouples, but are more accurate over a wider temperature range.

When to use a TC sensor? If you need to measure high temperatures, have a limited budget, or need a fast-responding thermometer, a thermocouple may be the perfect choice. Another advantage of TCs is that they can withstand harsher environments (corrosive material, vibration etc.).

Endress+Hauser has developed a unique sensor called iTHERM ProfileSens for high temperatures, pressures and aggressive media, consisting of a robust double metal sheathed MI cable and temperature profiling with up to four TCs in one cable.