Computational modelling of heat transfer in a porcelain-housed surge arrester

Surge arresters are equipment essential to the protection of the electric system against overvoltages. In an arrester, the housing temperature is a key factor to the assessment of its condition of operation. In this paper, a method to correlate the varistors temperature and the housing temperature of ceramic housing arresters is proposed. Models to evaluate the housing temperature from a given power input in the varistors are compared. Computational simulations based on the finite element method (FEM) were performed using a model of a 69 kV arrester with ceramic housing. The value of the housing's convective heat flux coefficient was estimated. The results obtained allow to quantify the heat transferred to the ambient by each mechanism and, thus, to define a model that is accurate and yet requires low computational effort.