Decomposition characteristics of SF₆ under partial discharges with point-to-plane electrode defect

Abstract

Field experience shows that the long-term existence of the partial discharge (PD) in gas-insulated switchgear (GIS) will gradually erode the insulation and ultimately cause disastrous insulation breakdown. The decomposition compound analysis of SF 6 in GIS is an effective method to diagnose the PDs caused by insulation defects. It is significant to clarify the decomposition characteristics of SF 6 under PDs, which is common in GIS. In this paper the discharge energy/charge and SF 6 decomposition under PDs with point-to-plane electrode defect were investigated under different factors such as needle curvature, applied voltage, gas pressure and moisture content (adsorbent). And the feature extraction of SF 6 decomposition under PDs was also discussed. The results show that the yields of SOF 2 , SO 2 F 2 and SO 2 tend to increase approximately linearly with the accumulation of PD energy. In addition, the needle curvature and applied voltage have a great influence on the discharge energy/charge and the yield of SOF 2 /SO 2 F 2 . Also, the adsorbents composed of KDHF-03 or F-03 have a certain effect on the discharge energy. Besides, the discharge energy and charge tend to decrease with the increased moisture content, and the yields of SOF 2 , SO 2 F 2 and SO 2 are affected by the humidity (250 L/L -2500 L/L) observably.Index Terms -Decomposition compound analysis, gas insulated switchgear, pointto-plane electrode defect, SF 6 .

Optical properties and decomposition mechanisms of SF6 at different partial discharge determined by infrared spectroscopy

“…It turns out that under all discharging voltages, the concentrations increase over time, while a higher voltage always leads to a higher concentration for a specific discharging time. The similar trend has been observed by Ding et al 19 They found that the SOF 2 and SO 2 F 2 decomposition products increase linearly with the accumulation of partial discharge energy. During the discharge, the strong interaction of highenergy electrons with SF 6 causes their rapid deceleration to the lower energy of electron capture and dissociative attachment.…”

Chemical kinetic modeling and experimental study of SF6 decomposition byproducts in 50 Hz ac point-plane corona discharges

“…The applied voltage and frequency are 30 kV and 50 Hz respectively. Ding et al [21] has recorded the repetition rates of individual discharge pulses for corona and sparks at different pressures, finding that the repetition rate of corona discharge pulses at 0.4 MPa is 2869/s, i.e. 57 pulses per cycle for 50 Hz voltage frequency.…”

“…Zeng et al studied the effects of trace water and oxygen on the concentrations of SOF 2 and SO 2 F 2 in a 50 Hz ac point-plane partial discharge and concluded that both H 2 O and O 2 have a more obvious influence on SOF 2 than on SO 2 F 2 [19,20]. Ding et al investigated the influence of the H 2 O content on the concentrations of SOF 2 , SO 2 F 2 and SO 2 in a 50 Hz ac point-plane corona discharge [21,22] and found that SO 2 could only be detected when the moisture content is higher than 1600 ppm and that the SO 2 yield increased with moisture content. Zhang et al reported that carbon nanotube arrays and TiO 2 nanotube arrays, which possess good sensing behavior towards SF 6 -decomposition species, are novel materials that can potentially be exploited as gas sensors for insulation evaluation in SF 6 devices [3,4].…”

“…There remains no complete chemistry set for SF 6 with impurities H 2 O and O 2 in corona discharge. For ac corona discharges, no chemical kinetic modeling to investigate the generation mechanisms of the decomposition byproducts has been performed; formation mechanisms have mainly been determined from the reactions that were proposed by van Brunt et al in their negative corona discharge model mentioned above [3,4,[17][18][19][20][21][22]. However, the discharge mechanism in an ac corona discharge is more complicated than that of the negative corona discharge, as a lot of repeated pulses occur in a single cycle and also the decomposition products take a long time to stabilize.…”

Decomposing Mechanism of SF6 under Positive DC Partial Discharge in the Presence of Trace H2O

“…It has been reported that the potential SF 6 decomposition species are significantly impacted by the content of H 2 O inside a device. , Up to now, many studies have been conducted to analyze the influence of H 2 O on the SF 6 decomposition mechanism under AC PD. Refs − revealed that the generation of SO 2 F 2 and SOF 2 would be facilitated with the increase of the H 2 O content.…”