Breakdown Voltage Behaviour of Leatherite Paper with or without a Void

This paper presents the breakdown behaviour of leatherite paper of different thicknesses without or with voids of different sizes. The study is essentially based on partial discharge (PD) mechanism occurring in CIGRE method-II electrode system under step-stress condition. The behaviour of leatherite paper, often used for electrical machine insulation, under AC voltage and under dry condition is demonstrated. It is found that the breakdown occurs at the central position of the insulation under study and is attributed mainly because of the PD.