A COMSOL multiphysics electric field analysis of an
ethylene-propylene rubber (EPDM) insulator is presented. The
132kVinsulator is an inverted post insulator that is taken from a
jumper loop. It has been in service in a severely polluted
environment for eight years. The insulator’s surfaces are
asymmetrically aged with organic dark deposits covering the
insulator’s surface, and with additional surface markings. The
insulator has a manufacturing artifact, known as the mold line,
which forms an elongated protrusion along the length of the
insulator. This artifact is introduced into the COMSOL model to
investigate its effect on the local electrical field. The reason for
this study is that the area surrounding the mold line is lighter in
color, with markings that suggest discharge activity. The regions
of the localized field enhancements are identified and correlated
with the ageing features, such as hydrophobicity loss, surface
roughness and discoloration observed after eight years in service.
A discussion whether the environment or the electric field are
dominating the ageing process of the insulator is included.