High voltage insulators pollution

For high-voltage insulators in service the contact angle is an abstract property that is not easy to measure and has to be interpreted. To con jare the influence of transfer of LMW into an artificial pollution layer on the leakage current, a high-voltage electrode arrangement as shown in Fig. 6 was used. 

Cycles of pollution and cleaning of silicone rubber samples show that hydrophobicity transfer is a dynamic process that depends on the amount of freely diffusible fluid components. It seems probable that the transfer effect is present during the whole lifetime of a silicone rubber for high-voltage insulators. 

Keywords High voltage insulators, silicone rubber, room temperature vulcanization, pollution, substations... 

The transfer of hydrophobicity onto solid pollution layers is possible by the diffusion of LMW that is contained in the silicone elastomers. This means that LMW diffuses into this layer and is lost when the layer is removed. In service this can be caused by wind or rain. To enable comparison of different materials, it was found useful to evaluate the dynamics of this process by measuring the dynamic contact angles on the surface of such pollution layers. For the tests, the procedure with a pollution layer of fumed silica described in [9] was used. With respect to a lifetime of high-voltage outdoor insulators of at least 25 years, we have to ask at the same time for the long-time effects and the repeatability of the transfer effect. 

H. Janssen, U. Stietzel Contact angle measurement on clean and polluted high-voltage polymer insulators in 10th ISH, Conf. Proc. Vol. 3, p. 149 - 152, Montreal, August 1997. 

J.M. Patel, V. Shrinet, M. Ramamoorty. Development of RTV sflicone coating for HV insulators installed in outdoor polluted environment, in 12th International Symposium on High Voltage Engineering 2001, Bangalore, India, p. 667-670. 

Usually power sources from 1 to 10 A are used (rarely 50-100 A), which at a voltage from 5 to 24 V or to 60 V ensure the realization of CP of modern underground and underwater objects. Due to the application of modem high quality coatings and insulation, the current demand for cathodically protected metal stmctures has decreased, creating new, beneficial conditions for the development of this technology, at the same time decreasing the hazard of pollution of the environment. 

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