Influence of load-shedding and night on SiR insulator environmental aging under AC test voltages

Insulators play a critical role in healthy transmission under the influence of operational stresses (OSs). OSs include environmental stresses (ultraviolet-radiations, seasonal heat and humidity variations, and pollution (inert and active), etc.) and electrical stresses (electric field distribution, corona, etc.). OSs can deteriorate insulators, jeopardizing the healthy transmission. In this experimental study, four silicon rubber (SiR) insulators with different concentrations of micro and nano-silica fillers are tested in a specially designed and fabricated compact environmental chamber for 1920 h under OSs, un-scheduled load shedding, and night factors for more realistic field insulators deterioration characteristics. Insulators' potential distribution, electrical field distribution, hydrophobicity, and leakage current characteristics are considered. Experimental results reveal OSs affected insulators' leakage current profile due to hydrophobicity loss and electric field distribution variations. Moreover, SiR insulators under OSs regained insulation characteristics due to heavier inner molecule replacement to the dissipated and degraded outer lower weight insulating molecules. This property provides a reusability opportunity for SiR insulators in power system networks, unlike traditional insulators.