Fiber Bragg grating sensors for temperature monitoring in oil-immersed transformers

A thermal sensor based on Fiber Bragg grating (FBG) is designed for online temperature measurement system in oil-immersed transformers. The measurable range is 30 °C to 150 °C, with resolution of 1 °C. Performance of the FBGs has been tested by temperature rising experiment in thermostat and online temperature measuring of transformer windings during short circuit experiment. Transformers equipped with the proposed FBG thermal sensors have worked stably for over a year, and the temperature data we achieved is stable and reasonable.