Análise do desempenho de para-raios de óxido de zinco.

Abstract

Zinc oxide(ZnO)-based surge arresters are applied in electric power systems as protection against overvoltages. The surge arresters limited the voltage peaks by transforming a part of the electrical energy into thermal energy. The electro-thermal performance of ZnO surge arresters has been studied during normal and abnormal service conditions and during laboratory tests. For this purpose, an electro-thermal model has been proposed which initially computes the energy input to the ZnO arrester for a given applied voltage. Subsequently, the computational model determines the temperature distribution and its temporal variation by means of the implicit formation of the method of finite differences. The electro-thermal computational model has been used to study the performance of a complete surge arrester and of a prorated section when subjected to laboratory tests. The computed temperature distributions and their time variations have been compared with experimental measurements. The good agreement between computed and measured results validates the electro-thermal model. The computational model has then used to study the performance of a hypothetical surge arrester configuration and a prorated section of this configuration. The model is able to predict the behaviour of the surge arrester during standard laboratory tests.