Physicochemical and Electrical Properties of the Insulation Pressboard Modified by Sputtering Al2O3 Nano-Structure Layer on Its Surface

Space charge accumulation is a major problem in the development of insulating materials. The aim of this work is to suppress charge injection from electrode into cellulose insulating pressboard under DC field by Al2O3 nano-structure layer. The Al2O3 nano-structure layer was deposited by radio frequency (RF) magnetron sputtering under room temperature. Physicochemical and electrical properties of the insulation pressborad modified by sputtering Al2O3 nano-structure layer on its surface was investigated. With reference to the new pressboard sample without prepared, space charge suppression was observed in the pressboard deposited Al2O3 layer. The Al2O3nano-structure does not decrease the breakdown voltage and thermal property of the sputtered cellulose insulation pressboard. This research provides a new point of view for improving the electrical property of the cellulose insulation materials.

I. Introduction

The requirements of power transmission distance and efficiency lead to the rapid development of high-voltage direct current (HVDC) transmission. Therefore, the oil-paper insulation system, which is the main insulation form of transformer, has also become the focus on transformer insulation research. However, space charge accumulation is one of the most challenging difficulties in HVDC insulation material [1] .The existence of space charge will cause serious distortion of the electric field distribution in the transformer, resulting in the failure of material insulation in the high field strength region, eventually leading to partial discharge or breakdown of the transformer internal insulation [2 – 5] . In recent years, more and more researchers are devoted to studying modified insulating materials that can suppress space charge. Kremena Masheva prepared LDPE with an AgNPs barrier layer deposited by a plasma process, which can clearly suppress space charge accumulation [6] . For cellulose insulation paper, nano-ZnO and nano-AlN were used to prepare nano-modified insulating paper, the influence of nano-modification on the space charge characteristics and the mechanism of suppressing space charge were investigated [7] .