New dc Insulator Design for Use in the Desert Environment

The performance of HV insulators is directly related to the amount, composition, and distribution of attached surface contaminants. Suspended contamination particles are brought to the vicinity of HV insulators by wind. Around an insulator string the dynamic behavior of contaminants, and hence attachment probability, is predominantly affected by electrostatic forces. The effect of the electrostatic forces is the more dominant under dc stress. This paper presents design modifications of HV insulator shapes leading to more suitable potential gradient distribution to achieve: Reduction of electric stress on each insulator unit by producing a uniform potential distribution along the insulator string, and reduction and/or redistribution of contamination deposition. The design philosophy adopted in this paper is based on the theory that by optimizing each individual component of an insulator, the composite design will be optimal. Theoretical and experimental set criteria and guidelines for the optimal component des gn are discussed taking into consideration electrodes, skirts and body configuration, leakage path and spacing, as well as dielectric material.