Transformer Oil Temperature Sensing Utilizing Bundle Plastic Optical Fiber Sensor

A bundle plastic optical fiber (POF) that works based on an intensity modulation technique is experimentally demonstrated to sense the temperature of transformer oil. The sensor was developed using a bundle POF that is located perpendicular to an aluminum reflective film with an airgap cavity between these two elements. The simplicity of the architecture allows the development of an economical optical sensor system. To avoid interference effects by other substances in the oil, the sensor head is encapsulated with a metal protecting tube. The temperature measurement was realized in this study by monitoring the output light intensity in the visible light spectrum. For linearity range from 40oC to 75oC, the tested sensor exhibits a sensitivity of 0.0064oC-1, a linearity coefficient of 0.95 and a resolution of 1.56oC. These results demonstrate the suitability of the developed sensor for temperature oil monitoring in an electrical power transformer system.