A temperature measurement technique using optical channel as a signal transmitting media

Temperature measurement and transmission of a signal safely to the control room for further processing is important for the process industry. In this paper, a modified head-mounted temperature measurement system using a thermocouple with opto-isolation has been developed. Here, the thermocouple is connected to the terminals, mounted on the ceramic base in the head of the thermo-well. It consists of two signal conditioners for thermocouple and AD590, both signal conditioning outputs applied to a summer circuit. The output of the summer circuit which is in the range of 1.73–3.43V, adjusted by a signal conditioning circuit, is applied to the middle electrode of Mach-Zehnder interferometer (MZI). MZI produces normalized optical signals according to the variations in temperature. These optical signals are then transmitted to the control room safely in the inflammable process industry. The transmitted signals are demodulated in the control room and then sent to the PC through an Opto-isolator circuit and DAS card. The necessary theory as well as mathematical equation has been derived. The experimental and simulation results are reported here.