Assessment of the state of mica-resin insulation using PD charge analysis and dielectric loss measurements

The paper presents the results describing insulation conditions of glass fabric-mica paper-epoxy resin material using PD charge analysis and dielectric loss measurements. The partial discharges (PD) charge was measured using a PD detector and a multichannel pulse-height analyzer. Parameters characterizing the state of the insulating material which were analyzed included total PD charge, maximum PD charge, charge of the most intensive PD pulses, the number of PD pulses recorded during observation time and dielectric loss. The experiments were carried out for two groups of samples of the insulating material: (i) prepared according to the production procedure required, (ii) overheated during the preparation process. The research showed that material defects can be detected more accurately by multichannel analysis of PD charge, than tan delta measurements