Partial Discharges (PDs) are reported as one of the main reason of insulation degradation and its measurement is most
effective, non destructive test often applied to know the insulation condition. Among many available methods acoustic
method of PD test is quite popular due to several advantages.In the presented work, a Fiber Bragg Grating (FBG) based
sensor has been developed for on-line condition assessment, capturing the acoustic wave produced by the PD event in a
prototype power transformer. A variation in acoustic pressure, changes the wavelength of the FBG reflected light, which
gives the indication of PD activity. Developed FBG based sensor is found to be superior over conventional PD sensors.