Charge accumulation characteristic on polymer insulator surface under AC voltage in air and C ₄ F ₇ N/CO ₂ mixtures

Abstract

Charge accumulation has always been a problem for the safe operation of gas insulated switchgear (GIS)/gas insulated transmission line (GIL) both under AC and DC. It is of great significance to investigate the behaviour of surface charge under high voltage. In this study, the charge distribution characteristics and accumulation mechanism on insulator surface in air and heptafluorobutyronitrile/carbon dioxide (C 4 F 7 N/CO 2) mixtures under AC voltage are studied via the means of surface potential measurement and inversion algorithm, combined with the improved method of controlling the truncated phase of AC voltage. The results show that under the needle-plate electrode structure, charge distribution on the insulator surface presents a three-tier concentric circle structure both in air and C 4 F 7 N/CO 2 gas mixtures, and the charge composition of the innermost circle is closely related to the truncated phase of AC voltage. Under the same amplitude of voltage, the range of charge distribution on insulator surface in C 4 F 7 N/CO 2 mixtures is smaller than that in air, with the negative charges domination. It is suggested that the characteristic of charge distribution in C 4 F 7 N/CO 2 mixtures is related to the larger electron attachment crosssection of C 4 F 7 N gas in a wide range of electron energy distribution.

Charge transport behavior in gamma‐ray irradiated poly(ethylene terephthalate) estimated by surface potential decay

“…Charge transport behaviour is considered as an important issue related to electrical performances such as space charge accumulation, electrical treeing and dielectric breakdown [37][38][39]. The carrier traps in polymer have great impact on the charge transport, and are thought to be generated from physical defects (molecular weight distribution, free volume etc.)…”

Mechanism Analysis of Particle-Triggered Flashover in Different Gas Dielectrics Under DC Superposition Lightning Impulse Voltage

“…The insulation performance of C3F7CN/CO2 gas mixture is more prominent, which may be due to the following reasons: 1) In terms of relative molecular weight, C3F7CN (195) is larger than SF6 (146), so the mobility of negative ions of C3F7CN molecules in the electric field is smaller. In addition, because the C3F7CN molecule has a larger collision cross section, the C3F7CN/CO2 mixed gas can effectively capture the electrons and ions generated after collision [24], thereby reducing the number of effective collision ionization and electron avalanches caused by electrons;…”

Surface Charge Properties of Epoxy Composites under DC Voltage Affected by Surface and Bulk Conductivity

“…Meanwhile, charge can accumulate on the insulator surface for long-term operation under the DC electric field [3][4][5][6][7][8]. The electric field generated by the surface charge can distort the initial field and possibly increase the risks of partial discharge or flashover [9,10].…”

“…It is reported that ion pairs generated in gas are the major source of charge accumulation on the insulator surface [9]. Cone-shaped insulators made of Al 2 O 3 -filled epoxy resin composites have been used to investigate the surface charge properties [4,5,10] and demonstrate the distortion of electric field distribution and the process of surface flashover [4]. Apart from the bulk effect of insulating materials, surface modification is utilized to generate more surface traps and suppress the charge accumulation [5,[10][11][12][13][14][15][16][17][18][19][20].…”

“…Energies 2021, 14,370 Apart from the bulk effect of insulating materials, surface modification is utiliz ate more surface traps and suppress the charge accumulation [5,[10][11][12][13][14][15][16][17][18][19][20]. In ad material properties, the influence of voltage type on charge accumulation is als [11].…”