Improving reliability of porcelain post insulators at electric power Substations

Abstract

At electric power substations, post insulators are designed for isolation and fastening of conductive parts of electrical installations. Insulators are installed on outdoor switchgear of substations as part of the main switching equipment. During operation, they are exposed to external atmospheric effects, mechanical and dynamic loads. Timely replacement of post insulators increases significantly the reliability of the main substation equipment at power substations. The question of improving reliability at transformer and traction substations is considered, external and internal factors associated with destruction of porcelain post insulators (PPI) are presented. It is established that the main cause of damage to PPI are sharp changes in ambient temperature, especially the transition of temperature values through 0°C. A model of a porcelain post insulator with an insulating body of elliptic shape is proposed. Operation of the proposed device is described. Analysis is presented of the ratio of the lengths of the axes of a circle and ellipse (major-to-minor) as related to spatial positioning in power loads. It has been determined by calculation that a post insulator should be installed in such a way that the major axis of the ellipse be aligned in the direction of the temperature gradient — sunlight, to reduce the impact of heating on the minor axis of the insulator.