Capturing the temperature of the workpiece in an induction heating system using thermocouple with minimal error

Thermocouples are very commonly used device to measure the temperature in industry and research. For measuring high temperatures, it is preferred over the other available alternatives for its simplicity and ease of use. It gives the direct voltage output over a wide range of temperature. But the main drawback of thermocouples is that it gets affected by electromagnetic field if present in the surrounding and gives erroneous result. Since the voltage generated by the thermocouple is of the order of micro volt, even a very small magnetic field can alter the reading of the thermocouple to large extend. Induction heating is a well-established technology and used in variety of applications. But due to the electromagnetic field generation associated with induction heating, the use of thermocouple for measuring temperature is difficult in this environment. An induction heating system is developed in Variable Energy Cyclotron Centre (VECC), for using in metal sample evaporation experiments where K type thermocouple is intended to be used to measure the temperature of the workpiece. Experimental studies have been carried out to compare the reading obtained from thermocouple with a standard, calibrated commercial IR sensor. Finally effective measures are put into application to capture the workpiece temperature with minimal error using thermocouple. This paper describes the development of the measurement set up, study and the corrective measures incorporated to achieve more accuracy in the temperature data taken in induction heating system using thermocouple.