الفهرس 
Impact of corona ring on the electric field distribution of high voltage polymeric insulators
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Abstract
High-voltage insulators are an essential component of high-voltage power transmission systems. In the design and development of composite insulators, calculations of E-field and potential distribution are used extensively. The electric field and voltage distribution on an outdoor suspension polymer insulator in clean and polluted conditions are investigated using Finite Element Method (FEM) electrostatic software. The 220 kV polymeric insulators model were calculated using two-dimensional model established in this work.
At first, insulator strings are supplied with auxiliary apparatus in an actual power transmission system to improve the electrical representation of the insulator strings. A corona ring, sometimes known as a grading ring, is one of the subsidiary accessories used with porcelain and polymer insulator strings to improve the electric field and voltage distribution around the insulator string. Corona rings improve the efficiency of an insulator strings in a variety of ways, including reducing corona and associated audible noise, radio waves, and television interference voltages, modifying E-field levels around the string, and causing more linear potential division along strings. Furthermore, corona rings improve string performance in polluted environments. All of these belongings of corona rings on insulator strings are largely determined by the corona rings’ design parameters. So E-field simulation has been studied by three essential parameters: the corona ring radius, the tube of the ring radius and the height of the ring from HV conductor to optimize E-field value and obtain the maximum value of E-field around the insulator and choose the best dimensions of ring at which the E-filed is the lowest.
In the second part the electric field and voltage distribution on the polymeric insulators is investigated under pollution condition, more conditions and shapes of water drops were added to investigate its effect on the E-field distribution. The obtained results show that with the increase of water drops size or numbers, the E-field increases and vice versa. The effect of water conductivity on E-filed is also investigated. In pollution condition the optimized values of the corona ring radius, the tube of the ring radius and the height of the ring from HV conductor are changed.