Electric field distribution of optimized composite insulator profiles under different pollution conditions

This paper presents the simulation results of electric field distribution for optimally designed medium voltage composite insulators under polluted conditions with and without water droplets. Four different profiles of 11 kV composite insulators were used. Simulation was executed for both typical and optimized insulators by using Comsol Multiphysics program. The main objective of this paper was investigating the effect of pollution conditions and water droplets on the electric field distribution of the optimally designed insulators. The effect of pollution layer thickness and conductivity on the electric field distribution was studied. The simulation results showed that the maximum electric field stresses of optimally designed insulators were less than those of typically designed insulators in clean, polluted and wet conditions. The results of this study are able to provide theoretical support to design and select the suitable profile of composite insulators in order to obtain better performance under clean and polluted conditions. Keywords: Electric field distribution, Composite insulators, Pollution, Water droplet

Achievement of the best design for unequally spaced grounding grids

The configuration of grounding grids which are used to earth electrical substations could be equally or unequally spaced. Unequally spaced grids were introduced to improve the requirements of the grids such as grounding grid resistance (Rg), ground potential rise (GPR), maximum touch voltage (Et) and maximum step voltage (Es) values. Also, unequal spacing can reduce the cost of the grids and enhance the level of safety for people and equipments. In this paper two different approaches were used to determine the best possible configuration of grounding grid. These approaches based on sequential multiplicative and sequential power techniques