Numerical investigation of electric field distortion induced by internal defects in composite insulators

Abstract

This paper presents an exhaustive study of numerical investigations based on three-dimensional finite-element method modelling of several non-ceramic insulators of 69, 110 and 230 kV having different internal semi-conductive defects in terms of size and position. The internal defects were positioned close to the high-voltage electrode, the ground electrode and at floating potential. The simulations effected on the distortion of the axial and radial E-field components close to the insulator shank between sheds. The results obtained showed that the radial E-field component is more sensitive to the presence of an internal defect as it shows a greater distortion in presence of the defect. It was also observed that the E-field component distortion increases with longer internal defect and that this increase is particularly important for a defect at floating potential. Moreover, it was demonstrated that the length of the insulator, for a defect of constant length, has no significant influence on the E-field component distortion. Finally, the results demonstrated that the presence of a grading ring, as used on the 230 kV insulator, does not have any influence on the E-field component distortion, independently of the defect position.

Keywords

• electric fields
• composite insulators
• finite element analysis
• electrodes
• distortion
• numerical investigation
• field distortion
• internal defects
• composite insulators
• three-dimensional finite-element method modelling
• nonceramic insulators
• high-voltage electrode
• ground electrode
• radial E-field component
• E-field component distortion
• voltage 69 kV
• voltage 110 kV
• voltage 230 kV