Understanding the construction, capabilities and limitations of thermocouples can help you select the right one and optimize its performance in a specific application.
The time constant of a temperature sensor (or any other sensor) is defined as the time required for the sensor to respond to 63.2% of its total output signal when subjected to a step-change in temperature. Sensor response time is not the same as the time constant, but is a measure of how long it takes for the sensor to reach its full output. Thus, response time can be defined as five time constants (Fig. 1), which is based on the fact that the temperature sensor is subjected to a step change in temperature.