Analyzing the Role of Filler Interface on the Erosion Performance of Filled RTV Silicone Rubber under DC Dry-band Arcing

A Novel Framework to Study the Role of Ground and Fumed Silica Fillers in Suppressing DC Erosion of Silicone Rubber Outdoor Insulation

“…The results indicate a faster inception of a stable eroding dry-band arc for the GS10 filled SiR compared to that of FS07 by 40-60 min (about 20% of the total testing duration). Similar outcomes were found in [12] for fumed silica filled composites against BN filled composites, which were attributed to the favorable interaction of fumed silica with SiR and a possible delay in the formation of the early surface residue by thermo-oxidation of the silicone volatiles.…”

“…Computing the RMS value for every second of the test run would suffice for representing the change in the leakage current values during the test and would provide a practical approach for acquiring the data with smaller storage requirements instead of saving the entire current waveform of 468 samples per second. Following the analytical approach presented in an earlier study [12], a statistical boxplot method is used to observe the distribution of the RMS leakage current values acquired during the IPT in 20 min time intervals. This statistical analysis allows one to observe the evolution of the dry-band arc from the intermittent state to the stable severe state, which is reflected in the changing distribution of the RMS leakage current values between consecutive time intervals in the boxplot.…”

“…It is important to note that despite having twice the thermal conductivity of the FS07 filled SiR, the GS10 filled SiR showed inferior erosion performance, which suggests that that the thermal conductivity is not the main governing factor in suppressing the erosion of SiR under DC voltage. In an earlier study [12], it was found that the favorable interaction of fumed silica with the SiR matrix was more decisive in determining the erosion performance of SiR under the +DC IPT than the improvement of the composite thermal conductivity using BN fillers. The difference in DC and AC erosion in silica filled SiR was thoroughly investigated and discussed in studies such as [11] and is not the subject of this work.…”

“…The reduction in the bar width is an indication of the changing nature of the dry-band arc, from intermittent to stable with less nonconducting periods. As illustrated in [10,12], the initial stage of the dry-band arc is intermittent with inconsiderable erosion noted on the composite surface. The subsequent stage, however, is stable with reduced nonarcing periods leading to severe erosion of the composite.…”

“…The coherency and porosity of such residue could shield the SiR material against progressive erosion under DC dry-band arcing [11]. In an earlier study [12], fumed silica was found to have a significant effect in suppressing DC erosion as compared to nano ATH and sub-micron boron nitride (BN) in SiR composites, despite the comparable thermal conductivities reported for all of the composites. Accordingly, the literature suggests that the role of silica fillers in suppressing the DC erosion in SiR is more than simply improving the composite thermal conductivity.…”