Comparison of PD characteristics and degradation in PET insulation with vented and unvented voids

Partial Discharge (PD) results from faults in power insulation systems and exacerbates failure. It is known that the presence of voids in solid and liquid insulation give rise to PD. Factors which control the PD activity include pressure and type of gas present. When PD occurs in insulation, pressure is created and gaseous products changed due to the energy input. A series of experiments is being carried out on artificial voids, created from layered sections of polymer. One set of samples has a void inside the polymer with no access to the outer atmosphere; a second set of samples is created with a vent connecting the void to the outer atmosphere. Both sample sets are stressed at the same electrical conditions for same period of time. Investigation of the physical and chemical differences and PD patterns recorded follows.