Efeito corona em isoladores poliméricos sob condições adversas

• Ano de defesa: 2016
• Autor(a) principal: Ailton Lopes Souza
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: ENGENHARIA ELÉTRICA; Engenharia elétrica
• Link de acesso: http://hdl.handle.net/1843/BUBD-A9PMMT

The corona effect is an undesirable phenomenon to the electrical system. Denre its harmful defects, degradation of surfaces of polymeric insulators is one of the most concern because of the possibility of conducting the fault system, leading to interruption in power supply. the appearance of the corona associated with high electric field levels, but these values depend on various parameters, among which are the environmental conditions, the geometry and configuration of arranging, beyond the insulating materials used. There are electric field of suggested values to ensure the absence of the corona, but these are not absolutely identical. Thus, corona identification forms become of great interest as a design criterion, manufacture and use of polymeric insulators. Due to the complexity of the phenomenon, it is difficult to model all processes involving their training. mathematical and computational models are developed to the corona of the presence of the pet. the applicability of these models is restricted by simplifications and considerations adopted, and usually intended to symmetrical arrangements, or well known. Due to the diversity of factors that influence the formation of corona effect is of interest investigation of the occurrence of this phenomenon and how this is affected by the adverse conditions to which the insulators are usually submitted. Within this context, this study aims to identify the start of the corona effect in polymeric insulators, analyzing some of the factors that contribute to the formation of this, in particular the deposition of drops of water on its surface and its association with pollution. It should be noted that studies indicate that there is a reduction of breakdown voltage quano polymeric insulators are subjected to these conditions, but there are no conclusive results about the corona effect. Thus, experiments were performed using metal hemispheres to represent drops in arrangements under uniform field (parallel plate capacitor) and nonuniform (polymeric insulator). These experiments focused on the study of the influence of the size and placement of the droplets to form the corona. For the analysis of the results, both the increase in the volume drop, as its proximity to the potential applied reduces the corona inception voltage. these results were in good agreement with the available literature. To simulate the combination of drops of water and pollution; different conductivities water drops were used in the experiments, in order to investigate the influence of these conditions in the corona inception voltage. there was clear influence of the conductivity in the formation of corona effect. In the experiments 14% reductions were observed, reaching up to 36% in the corona inception voltage, depending on the severity of simulated surface contamination. In summary, through a series of experiments it was found that the corona starting voltage is reduced by the presence of water droplets on the surface of composite insulators, this being marked reduction when the association of these drops pollution. Thus, under severe operating conditions, there is greater facility for the onset of corona discharges. This can speed up the aging process of the polymer