Influencing Mechanism of Adhesive on Partial Discharge of Pressboard Block under AC/DC Composite Voltage

Abstract

The phenolic adhesive and casein adhesive are two kinds of adhesives used in pressboard block production. The partial discharge characteristics of pressboard block containing the two types of adhesives under AC, DC and AC/DC composite voltage are researched in this paper. Using the block samples with phenolic adhesive or casein adhesive, the partial discharge characteristics, flashover characteristics and the influence of the adhesive layer orientations were obtained. The results show that the use of adhesive may introduce a weak zone of insulation performance and reduce the insulation strength of the pressboard block. There exist polar effects on partial discharge and flashover characteristics under DC voltage, and there is no significant difference in the partial discharge characteristics and flashover voltages between the pressboard blocks with casein and phenolic adhesive. The phenomena are analyzed in terms of molecular characteristics of adhesives and cellulose pressboard. The research results of this paper provide significant theoretical and practical reference for the optimization of transformer insulation materials.