Dry-Band Discharges Dynamic at the Surface of SiR Textured Insulator During AC Inclined Plane Test

摘要

Polymeric insulators are widely used for HV overhead lines and substations in polluted areas because of their hydrophobicity. However, it has been seen that the shank regions are vulnerable to thermal damage from partial arcs. Textured insulators have recently been proposed in order to reduce both the leakage current density and electric field strength in such regions, and by the same means to achieve an increase in creepage length. Inclined plane testing according to IEC 60587 is an indicator for the evaluation of the resistance to tracking and erosion properties of the silicone rubber formulation. In the case of conventional plane SiR insulators, it has been seen that dry bands were readily formed at or near the ground electrode, and these were often bridged by arc-like discharges causing deep erosion. By using IR camera, we measured the thermal activity of dry bands and the associated discharge in order to estimate the dynamic of the streamer/sparks with time. The observations show that the displacement of those discharges is not uniform and depends on the insulator surface state. Correlation between the temperature variation and the discharge position will made and a comparison with leakage current evolution will be discussed. A relationship is proposed also for the calculation of both of the insulator power loss and resistance.