Development of Laboratory Test Method to Perform Artificial Pollution Test on Composite Insulators Intended for HVDC Applications by Solid Layer Method

To transmit electric power to long distance load centers HVDC transmission lines are widely used in recent years. Insulators are one of the vital equipment in transmission lines and are exposed to different ambient atmospheric pollution. In some cases, may be due to either of very high pollution or improper dimensioning, a flashover (FO) may occur across insulation at normal operating voltage. Such unwanted FO may be avoided by optimum design and dimensioning of insulators. Pollution performance studies in many cases determines the dimensioning of insulators. IEC TS 61245 gives guidelines to perform artificial pollution test on glass and ceramic insulators, intended for HVDC application. Nowadays, due to inherent advantages, utilities are using composite insulators and till date no standardized test procedure is available to conduct artificial pollution test on composite insulators. However, for optimum dimensioning of composite insulators, a standard test procedure is mandatory. In this work, following the guidelines of IEC TS 61245 and CIGRE WG C4.303 round robin test (RRT) report 555, a laboratory developed test method is proposed to perform artificial pollution test on composite insulators intended for HVDC applications by solid layer method. Step-by-step procedure of the proposed test method along with its validation in terms of representativeness and repeatability is reported. Reproducibility of developed method is validated successfully by performing test on large scale, ±500-kV composite insulators intended for HVDC applications.