Study On The Composite Insulator Material’s Volume Resistivity Characteristics Under Artificial Corona Aging Condition

The HTV SIR (High Temperature Vulcanization Silicone Rubber) has becomethe prime choice for the shield of composite insulator. The excellent hydrophobicityand the hydrophobic mobility are the main reason for its widely using. Other thanthe traditional inorganic material like ceramic, under the operational condition, theorganic HTV SIR is focusing more serious aging problem. As the operational yeargains, the flashover and the accident occurred due to the composite insulator aging.The evaluation of the aging degree has been a key problem in the compositeinsulator’s operation. A self-design three-electrode volume resistivity-temperaturesystem was used to test the HTV SIR samples’ volume resistivity. The HTV SIRsamples were from the production line, the operational line and the laboratory’scorona aging. The paper was focus on applying the volume resistivity-temperaturecharacter on the HTV SIR’s aging degree.First the testing parameters like the size of three electrodes, the testingtemperature were chosen based on the shield’s character. Then the testing systemwas built. The stability and the anti-interference ability were checked. The test ofnew samples from ten manufactures showed that the new HTV SIR fit the linear lawinln v1Tcharacters.To obtain a more average aging area than the single needle-pad corona system,a multi needle-to-plane was developed. The parameters were set based on theelectrostatic field simulation and the validated device. The HTV SIR from onemanufacture was chosen. The longest corona effect time was set to1000hours.Some time points were set to research the connection between corona’s time andaging. The result showed as aging time developed, the linearity inln v1Trelationwent down. The linearity broke first occurred in lower temperature testing point.Then the FTIR, SEM and XPS analysis were done. The results show that aftercorona effect, the oxidation happened in surface. The macromolecular chain brokendown, the low molecular occurred. The surface became rough and the hole appeared.As corona aging time went on, the situation worse. To investigate the realoperation’s aging phenomenon, the composite insulators from two manufactureswere chosen. The volume resistivity-temperature results showed that after years ofoperation, under the same temperature, the samples’ volume resistivity decreased.The linearity went down; the worst situation was the linearity disappeared. TheFTIR and SEM testing proved the samples under operation suffered more thancorona aging. Further to see, the samples withoutln v1Tlinearity was with themacromolecular broken. At the end of the paper, the comparison between operation’s samples andcorona’s aging samples had been done. The high polymer’s theory had been used toanalysis theln v1Tlinearity and it’s disappeared. Base on the testing and theanalysis, the author hope the volume resistivity-temperature testing method to bethe new tool for the evaluation in HTV SIR aging degree.