Raman spectroscopy of 200 kV and 400 kV service-aged silicone rubber insulation in the Gulf region

In this paper Raman spectroscopy is performed on silicone rubber housing materials that have been taken from 200 kV and 400 kV transmission line insulators, located in the Gulf region. The service areas of these insulators feature heavy depositions of sands and dusts yet with intermittent durations of fog and wetting on the surface. In addition, the creepage distances have been selected for heavily polluted conditions as per IEC 60815, thereby expecting light aging conditions for the analyzed housing materials. The increase in the Raman band intensity of Si-OH rationed to the Raman band intensity of Si-O-Si is found as a useful aging indicator for the analyzed surfaces. On the other hand, a careful analysis is required when using the Raman band intensity of alumina tri-hydrate rationed to the Raman band intensity of Si-O-Si in order to indicate the reduction in the polymer content due to aging. Ultra-violet radiation oxidizing the surface is the main factor reported to deteriorate the analyzed materials. An increased influential effect is also speculated for both the aging time in service for the 200 kV insulators and for electric field enhancement inducing surface discharges as approaching the energized side of the 400 kV insulators. Using Raman spectroscopy to assess the condition of service-aged silicone rubber insulators can be advantageous as, with a special apparatus, this method can be implemented on site.Peer reviewed: YesNRC publication: Ye