Zinc oxide (ZnO) surge arresters have been widely used nowadays in
overvoltage protection of transmission line systems, particularly in
the event of lightning and switching surge [1]. The most recently
developed ZnO surge arresters do not require serial gaps owing to
their excellent non-linear properties which react against
overvoltage in a very short period of time [2]. However, previous
analyses have shown that the removal of the serial gap causes the
arresters being stressed by both power frequency voltage and
transient overvoltage [1]. Excessive voltage stressing the arresters
might result in degradation of their thermal and electrical
stabilities, and consequently reducing the energy absorption
capability [3]. As the performance of the ZnO arresters are
primarily determined by the energy absorption capability, it is
necessary to further evaluate the combined effects of AC voltage
stress and surge operations on their electrical, thermal and
mechanical properties