Electrothermal Finite Element Analysis of a Pluggable High Voltage Surge Arrester

In power transmission systems, overvoltages occur due to lightning strikes and switching operations. Surge arresters protect power system equipment from these overvoltage events. Gapless, air insulated arresters have been in operation for almost four decades. Their operating principle is based on metal oxide resistors, which feature a highly nonlinear electric conductivity. Recently, progress has been made in simulating the electrothermally coupled behavior of air insulated surge arresters. These finite element simulations contribute to a better understanding of the arrester behavior in various operating conditions. This paper investigates pluggable surge arresters, which were introduced for high voltage applications about ten years ago. Due to their compact setup, their electrothermal behavior differs significantly from conventional arresters. The electric field and temperature distribution along the resistor stack is analyzed by coupled electrothermal field simulations. The modeling concepts from conventional arresters are therefore adapted to the case of the pluggable arrester. A validation against experimental data is presented. A conventional and a pluggable high voltage surge arrester are compared based on electrothermal finite element simulations of the steady state operation. The effect of field grading systems on the temperature distribution is discussed.