Effects of ZnO magnetron sputtering on surface charge and flashover voltage of oil‐impregnated paper

Abstract

With the aim of exploring an alternative method of nano-doping in cellulose paper and improving flashover strength of oil-impregnated paper, radio frequency (RF) magnetron sputtering method is introduced into the structural modification of insulating paper for converter transformers. In this experiment, insulating paper was treated with ZnO sputtering for 0, 7.5, 15 and 30 min, respectively. The surface morphology of dry paper was observed with a scanning electron microscope. The bonding mode of sputtered ZnO particles with cellulose matrix was investigated via attenuated total reflection infrared (ATR-IR) spectroscopy and mechanical property of the sputtered samples were studied. Surface and volume conductivities of the oilimpregnated sputtered paper were measured. Moreover, the charge dissipation characteristics of sputtered insulating paper was investigated by means of surface potential decay. In addition, trap distribution and carrier mobility of specimen were further obtained. Finally, the DC flashover strength were tested. The results showed that ZnO magnetron sputtering had a distinct influence on the structure of the insulating paper, resulting in the formation of hydrogen bond and chemical bond and an increase of the surface and volume conductivities. ZnO sputtering was found to decrease the initial potential and accelerate charge decay. Moreover, appropriate sputtering enhanced the surface flashover strength.

Improvement of surface flashover in vacuum

“…The experimental results indicate that the doped ZnO nanoparticles introduce deeper traps, which reduces carrier mobility, secondary electron emission and space charge accumulation [139]. Recently, to explore an alternative method of nano‐doping in insulator, radio frequency magnetron sputtering method is proposed to modify the cellulose paper, leading to ZnO fillers not only exist on the surface of cellulose paper but also enter into its interior [140]. After sputtered for 15 min, the surface flashover of oil‐impregnated paper is improved by 23%.…”

Promising functional graded materials for compact gaseous insulated switchgears/pipelines

“…To fabricate ɛ ‐SFGM insulators for AC E‐field relaxation, the magnetron sputtering method was proposed to deposit huge‐permittivity BaTiO 3 layers on insulator surfaces [47]. The E‐field relaxation effect of the surface ɛ ‐uniform insulator has a ‘saturation effect’.…”

Dynamics of surface charge and electric field distributions on basin‐type insulator in GIS/GIL due to voltage polarity reversal

“…Therefore, the power flow reversal of HVDC transmission systems is achieved by changing the polarity of the voltage [10]. At present, the research on the influence of voltage polarity reversal on insulation mostly focuses on converter transformer [10][11][12][13] and DC power cable [14][15][16]. Under HVDC conditions, the insulation properties of the converter transformer and power cable will reduce due to the effect of the oil-paper interface charge and space charge, respectively.…”