Acoustic partial discharge measurements for transformer insulation-an experimental validation

Acoustic partial discharge (PD) measurement is a useful method of identifying and locating PD in a power transformer in service. In this paper an experimental validation has been performed on a transformer insulation model using an acoustic PD detector. While the efficacy of the method is proved, it is observed that the signal gets attenuated significantly when it passes through pressboard barriers. Even though acoustic PD values can be correlated with the maximum discharge magnitude for a single discharge activity in the laboratory simulations, this relationship could not be established during actual PD measurements in a transformer at site, as the acoustic PD signal depends upon many factors.