Simulation approaches using the finite-element method (FEM) can be categorized in how they
represent the electrical response of surges arresters. A purely capacitive representation assumes negligible resistive effects in continuous operation, e.g. [6]. It is the most conservative approximation as it does not take conductive field-grading effects into account. The industry norm [2] recommends a capacitive–resistive representation of the MO resistor column. This is equivalent to an electroquasistatic (EQS) approach assuming a field-dependent
MO conductivity, adopted in [7]–[9]. The strong nonlinearity and temperature dependence of the electrical characteristic requires, especially for ultrahigh-voltage systems, the analyses
of the potential and, additionally, the temperature distribution. Thus, a heat transfer model for the investigated arrester must be introduced [10], [11]. Station class arresters require
substantially more advanced modeling approaches compared