Study of propagation behaviour of partial discharge acoustic signals in a 3-D model tank

In this paper an attempt is made to simulate the propagation behaviour of Partial Discharge (PD) acoustic emission (AE) signals in a simple experimental tank. The mathematical model has been developed in the form of partial differential equations (PDEs) for PD acoustic wave propagation in transformer oil and also in a steel tank. The PD is modelled as a point source at the centre of the tank. A Finite Element Analysis tool (FEMLAB), has been used to simulate the propagation of the acoustic waves. The reflection and transmission behaviour of the AE wave front on the steel wall tank is studied. It was also observed experimentally that for an impulsive PD event, when an AE signal travelling in the oil falling on the tank wall, that nearly 82% of the signal is reflected at a frequency of approximately 154 kHz. Hence nearly 18% of the acoustic wave would be transmitted through the tank wall. The theoretical and experimental results are in good agreement. This result is important as it helps quantify and understand the significant amount of energy from an acoustic PD source which may be lost prior to being measured by an acoustic sensor.