Aging Evaluation And Nano Modification Of Silicone Rubber Insulators

Silicone rubber insulator has been widely used in UHV transmission line for itsadvantage in mechanical and insulation performance. Its state is a mainly element forthe stability and the reliable operation of power systems. For the high voltage and thestrong electric field， the corona discharges often occur on the tiny spikes in theselines. Moreover，pollution flashover or wet flash would occur under the fog，dust orrain. All these above would influence the state of the insulator surface， acceleratesilicone rubber aging， and even lead to failures.In this paper， the influence of the corona discharge on the silicone rubber wasstudied by DC corona experiment. Base on the acoustic emission， the method for theevaluation of the insulator surface hydrophobicity was studied by the statics test andthe dynamic test. To study the influence of the nano-scale BN powdered on thesilicone rubber erosion resistance ability， the slope experiment was carried out.By using the multi-needles-plate corona unit， the charge was injected into thesilicone rubber and droplets. The characteristic of an electrified droplet oncorona-charged silicone rubber nanocomposite surface was observed under dc voltagestress. The relationships among the charge density， the contact angle， and theflashover voltage via the droplet were obtained. The results show that chargeddroplets deposited on charged surface has a negative effect on the nano filled siliconerubber composites that can make the flashover occurs at lower voltage.The acoustic characteristics of the surface discharges， based on the staticdroplets test and the dynamic droplet test， were investigated to evaluate thehydrophobic properties of silicone rubber insulator at different ageing degrees. Thespecimens were prepared by dc corona degradation. Simulation was employed toestimate the ageing degree of the specimens， comparing with the insulator on service.The relationships among the flashover voltage，the signal power，the pulse number，and the contact angle via the static droplets test were obtained. For the dynamicdroplets test， it is found that the pulse number， the voltage rang， the maximumslope and the signal energy present the obvious tendency with the hydrophobicitydeterioration or loss. The shape parameters of the data distribution reflect thedifference of specimen surface hydrophobicity. Therefore， the obtained results indicate that the acoustic characteristic of discharge is sensitive to the hydrophobicproperties.By using the slope experiment， the influence of the nano-scale BN powdered onthe silicone rubber erosion resistance ability was studied. The relationships among thesurface temperature distribution， the erosion depth， the loss weight and othercharacteristics via the mass fraction of the nano-scale BN powdered were obtained.The results show that the nano-scale BN powdered has a positive effect on thesilicone rubber erosion resistance ability.