Measurement Device and Procedure for Thermocouple Inhomogeneity Detection

The paper presents an automatic system for thermocouple inhomogeneity detection achieved by moving the thermocouple through temperature gradients and measuring any Seebeck voltage variation. It is a flexible portable system enabling accurate and reproducible measurements even for a great number of repetitions and long measurement periods. Also, the workload on the user performing such measurements is reduced. The vital part of the system is a microcontroller controling the stepper motor for carriage movement. It is also used for communication with a PC computer, where a custom-written program in LabVIEW serves as a user interface. The mounting of the system is developed for vertical as well as horizontal thermometer movement. This allows the system to take advantage of the existing laboratory equipment since it can easily be mounted on different baths and furnaces. A brief description of procedures for thermocouple inhomogeneity detection is given. Measurement results of thermal emf for inhomogeneity detection are presented for different heat sources such as water bath, oil bath and heat-pipe furnace.