The definition and measurement of the time constant and response time of thermal converters

The dynamic characteristics of a thermal converter for measuring alternating current or voltage are of some importance in a number of applications. The time constant and response time are the characteristics most often required. The change of emf (electromotive force) of a thermal converter after a step change in heater current is only approximately exponential, so that the definition as well as methods of measuring these quantities must be specified. This investigation of methods of measuring these quantities was undertaken at the request of the AIEE Committee on Indicating and Integrating Instruments.