Mechanical imperfections related to the manufacturing of
porcelain insulators may originate from any of the process
steps, e.g. blending the raw materials, dehydrating the cake,
hot-pressing or glazing and may lead to premature failure in
service. Therefore it is essential to test the dielectric durability
of the insulator after manufacturing. Throughout service life,
aging and contamination of the insulators takes place, gradually
degrading the insulators properties. Regarding the structure of
insulators, it must be considered that they are not mounted
directly onto the rod on the supporting beam. A less than
perfect fit would cause mechanical stresses that would break
the porcelain or glass upon installation or afterwards. An
intermediate connecting substance is used to fit the insulator
onto the rod. In the simulation those materials are hemp
cellulose paper (for simplification assuming that hemp
cellulose paper and hemp fibers electric properties are similar)
for the glass insulator and nylon for the porcelain insulator.