Short circuits between phase conductors occurred because of
lost spacers. Some conductors dropped while energized, representing
a risk to those around the line [4]. After these events,
the Mexican electric utility (Federal Commission of Electricity,
CFE for its acronym in Spanish) decided to replace the lines
with SCS by lines with hybrid systems.
It is well known that electrical tracking on the SCS insulating
materials is associated with the high electric field concentration
around the contact area between the covered conductor and the
spacer [5]–[9]. The high field is a consequence of the zero-angle
contact points (wedge effect), and it is usually considered to be
affected by the dielectric compatibility of the materials. However,
it has been shown that even when the materials in contact