Frequency dependent propagation characteristics of partial discharge acoustic emission signal

Oil pressboard insulation used in transformer deteriorates due to partial discharge (PD) leading to premature failure. Online monitoring of PDs can reduce the risk of catastrophic failure of transformers. Being non invasive and non interference prone, acoustic technique based PD on-line monitoring is advantageous. Acoustic emission (AE) signal produced by PD are detected by sensors mounted on the tank surface. AE signal attenuates while propagating from source to sensors. This attenuation is frequency dependent. Higher frequency component attenuates more than lower frequency components. PDs are classified according to frequency components of PDAE signal. This paper presents experimental results and analysis for frequency dependent propagation characterization of PDAE signal of laboratory simulated PDs in oil pressboard insulation system using point plane electrode system. The measured PDAE signals are analyzed using Discrete Wavelet Transform (DWT). The results highlight the possible use of frequency dependent propagation characteristics of PDAE signal for source location and for avoidance of misclassification.