Fig. 4(a) shows the stationary temperature distribution in the arrester (deposited on a grounded surface) after ≈ 4 h of continuous operation at the rms voltage Uc = 345 kV and power frequency f = 50 Hz. In Fig. 4(b), the transient temperature along the arrester axis is monitored every 15 min until stationary state is reached. The initial arrester and constant ambient air temperature is 293 K. Note that the temperature difference between the bottom and top segment of the arrester amounts to more than 80 °C. Thus, the respective arrester segments operate at very different working points on the electrical characteristics (Fig. 1). These results, as well as
the temperature profiles obtained in the simulation, are in a very good agreement with the measurement considering the large degree of uncertainty of parameters and environment
factors affecting arrester operation.