Effect of irregular-shaped Cu particles on transformer oil PD characteristics under varying electrode configurations

摘要

Electric field distribution depends on the geometry of internal parts of a transformer, which may experience as uniform, quasi-uniform and non-uniform fields. In the vicinity of these fields, particles present in transformer oil undergo various field stresses, especially in case of conducting particles. Any variation in local field stress causes relative change in partial discharge (PD) characteristics. Mineral oil in transformer may contain particles having different sizes, shapes and numbers. The irregular shape of particles can cause serious effects than smooth spherical particle. This study investigates the effect of irregular-shaped copper (Cu) particles in transformer oil PD characteristics under varying electric field. Furthermore, to study the effect of particle size, large-, medium- and fine-sized irregular-shaped Cu particles were used. Phase-resolved PD (PRPD) pattern, PD characteristics such as magnitude, number, discharge power, rise and duration time were analysed. The observed PRPD patterns were comparatively similar regardless of applied electric fields and particle size. The experiential PD characteristics are observed to depend on electrode configuration, particle size and applied voltages. The measured discharge power indicated that fine-sized particles required minimum applied voltage to dissipate sufficient discharge power in oil compared with medium- and large- sized particles.