Surface analysis of asymmetrically aged 400 kV silicone rubber composite insulators

Abstract

Surface analysis of 400 kV silicone rubber composite insulators is presented. These insulators have experienced 15 years of service on a coastal 400 kV transmission line. Inspection of the insulators shows low levels of degradation through cracking and oxidation of the surface. This has been quantified by microscopy, energy dispersive Xray analysis (EDX), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The analysis shows non-uniform ageing over each shed and ageing on the south side more advanced than on the north side. It is believed that non-uniform ageing was due to environmental factors including natural UV radiation and prevailing wind direction, and the resultant pattern of growth of organic species. EDX and FTIR were found to be the most useful and effective tools for analysis of these polymeric insulators.

Micro characterization and degradation mechanism of liquid silicone rubber used for external insulation

“…FTIR spectra are used to analyze the existing forms of certain groups [14][15][16], as is shown in Table 3. It is shown in Figure 7 that the heights of absorption peak are negatively correlated to the degradation level.…”

Experienced gained from 132 kV EPDM composite insulators in a coastal environment

“…This reduction in hydrophobicity may be entirely due to discharge activity and is local, unlike the reduction on the top surfaces which is due mainly to solar UV radiation previously reported on south-facing silicone rubber surfaces [3,4]. However the dark layer may also provide protection to the underlying surface from ambient solar UV radiation, also helping to maintain its high contact angle.…”

“…Also from these images it can be seen that the two sides have different levels of darkness. This difference in brightness may occur because the orientation of the insulator and the resulting asymmetrical ageing due to natural solar UV light previously reported on silicone insulators [4,5]. shows that the region adjacent to the mould line is actually smoother and less crazed than the region a little further away.…”

“…An essential step in this process is to understand the processes behind surface ageing of materials before severe damage occurs. Few reports of detailed measurements of service-aged insulators which are still in the early stages of ageing have been published [3][4][5][6]. This paper adds to that knowledge.…”

Electric field analysis of 132kv EPDM insulator and correlation with ageing features

“…The rate that composite insulators age is dependent upon the environmental conditions such as electrical stress, geographical location, solar and UV radiation, temperature variations, precipitation as well as wind speed and direction [5]. It has been reported that non uniform exposure of composite insulators to environmental stresses has led to asymmetrical ageing between south-and north-faces of both SiR [6] and EPDM [7] transmission line insulators.…”