Partial discharge and breakdown characteristics of moving transformer oil contaminated by metallic particles

Partial discharge behaviour due to irregular‐shaped copper particles in transformer oil with a different moisture content of pressboard barrier under uniform field

“…At each level of applied AC voltages, PD pattern was observed for 1 min. PD pattern mostly appears around 90° and 270° phases of the applied AC voltage [6, 9, 10]. Fig.…”

“…The study indicates that at the lowest oil velocity, the discharge number and amplitude increase substantially, whereas, at a higher velocity, PD activities are minimum. Pan et al [10] further investigated the PD parameters and breakdown voltage due to the effects of metallic particle concentration and particle size in moving transformer oil. However, in the real case, an oil‐filled transformer perhaps contains various types of particles with different size, shape and number.…”

Contribution of free iron particles to PD characteristics in flowing transformer oil at DC voltages

“…The number of discharges is closely related to the electric field strength between a particle and an electrode and the number of particle‐electrode collisions [12]. Based on the model, the electric field distribution around a particle was calculated first when the particle approached electrodes.…”

“…F other mainly included the buoyancy force ( F bu ), the additional mass inertial force ( F VM ), the pressure gradient force ( F p ), the Magnus lift force ( F ML ) and the shear lift force ( F SL ) [21, 22]. Additionally, the collisions between particles and electrodes constitute the main S contribution to PDs in the transformer oil contaminated by metallic particles, while the probability of particle–particle collisions is so low that the PDs induced by the collisions can be neglected [12]. As a result, the collisions between particles in this model were ignored.…”

Review about PD and breakdown induced by conductive particles in an insulating liquid

“…In recent years, Tang et al [93,94] took the lead in proposing that the circulation of transformer oil due to various cooling systems could affect the migration of particles and subsequently alter the PD and breakdown characteristics of transformer oil. Then, comprehensive researches were executed, which involved observation and simulation of moving trajectory, PD and breakdown tests [95][96][97][98]. When the oil flowing was perpendicular to the applied field, it was found that the conductive particles moved forward with oil flow and oscillated owing to the electric field, as shown in Fig.…”