Investigation of partial discharge between moving charged metal particles and electrodes in insulating oil under flow state and AC condition

Abstract

Theoretical analysis and experimental study were conducted to clear the partial discharge (PD) between moving charged metal particles and electrodes in insulation oil under flow state and AC condition. The rise time of the PD pulse current is tens of nanoseconds, which is not affected by velocity and voltage. The dominant frequency component of the ultra-high-frequency (UHF) signal due to charged metal particle movement is near 0.39 GHz, which is independent from velocity and voltage. The magnitudes of PD UHF signals are discontinuous and the time of occurrence of PD depends on the trajectories of charged metal particles. PD Φ-U-N maps clearly indicate that the phase information of the PD UHF signal on the maps is similar regardless of flow velocity and AC condition, but the voltage intensifies the PD and the flow velocity weakens the PD. The trajectories of charged metal particles in the horizontal transformer oil tract were investigated through stress analysis of charged metal particles under flow state and AC voltage. When charged metal particles move along the oil tract under the oil flow, reciprocating oscillation simultaneously occurs in the vertical direction.

Experimental Analysis of Modified CNTs-Based Gas Sensor

“…During long-running process, insulating oil and other insulating materials of transformer under the effect of electricity and heat will gradually age and decompose, resulting in the production of gases such as low molecular hydrocarbons, CO, and CO 2 that get dissolved in insulating oil [23,24]. When the transformer is in normal operation condition, the outside factors such as electricity, heat, and mechanical stress cannot break chemical bond of insulating oil and insulation paper (plate).…”

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

“…However, it is frequently ignored, and the transformer oil is assumed to be stationary. 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].…”

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

“…Each one had a diameter of 200 mm and a thickness of 10 mm. Other details about the system could be acquired from our previous paper [13]. Moreover, a high‐speed camera with a maximum frame rate of 225,000 fps, a maximum pixel of three million, and a minimum exposure time of 1 μs was employed to observe the particle motion.…”

“…Recently, our group preliminarily considered the influence of oil flow on the PD characteristics [11–13]. It is found that the increase of oil flow speeds reduced the discharge frequency and the PD amplitude under AC voltages.…”