An experimental method to determine the electro-thermal model parameters of metal oxide surge arresters

The energy absorption capability of a metal oxide surge arrester is limited by the temperature of its elements. To predict this temperature, a computer model can be a valuable tool, but it needs to have exact parameters. An experimental method using only a single test to determine such parameters is proposed. An electrothermal model couples the electrical heat production from metal oxide varistor elements with the thermal characteristics of the housing. The watt losses are computed from the voltage-current-temperature characteristic of the arrester when the applied voltage and temperature are known. With the proposed experimental method for the determination of the thermal parameters, a single high-energy discharge is sufficient to find the four values of the thermal model. The method is based on linear system analysis and makes use of least-square minimization curve fitting. The method is validated with real data on a full section of a 735 kV system station class arrester. The influence of error in the parameter values is evaluated by a sensitivity analysis