3D Stator Bar Modelling with Investigation on the Effect of Shapes and Sizes of Cavities and Distribution of Electric Field

Insulation system is one of the most vital elements in high voltage equipment and hence, investigation on the condition and mechanism of failure of high voltage insulations is essential. This paper presents the study on the effect on the cavity's position and sizes and the corresponding electric field and potential distribution in the 3-Dimensional stator bar insulation. The 3D stator bar modelling is implemented using COMSOL software and simulated using Finite Element method (FEM). The outcome of the simulation work shows the uniformity and strength of electric field in the stator bar insulation is affected by the sizes and shapes of the cavity. In terms of the shapes, the ellipsoidal cavity sustains the greatest electrical stress of magnitude of 5.34kV/mm as compared to the spherical cavity which withstands only 4.05kV/mm when the cavities size is 0.22mm. Apart from that, the electric field intensity of ellipsoidal cavities is discovered to endure a drop of around 13-14%, while a drop of 22-23% for spherical cavities when the cavity sizes increased from 0.22mm to 1.10mm. The results from this modelling work aid in improving the understanding over the electrical breakdown in stator bar insulation system.