Electrical tracking and combustibility performance of RTV silicone rubber composite insulation

The overhead electricity network heavily relies on silicone rubber-based composite insulators. The insulation possesses superior flashover and hydrophobic properties which is desirable for reliable network operation. However, its poor electrical tracking and combustibility resistance is a concern. This work reports the electrical tracking and combustibility performance of silicone matrix using alumina trihydrate (ATH), graphene nanoplatelets (GN) and milled glass fibre (GF). The test samples with different formulations such as S0 (pristine), S1 (30%-ATH) and S2 (30%-ATH, 1%-GN, 5%-GF) are fabricated, and the tracking resistance is evaluated according to IEC60587 using criterion 2. In addition, the combustibility is evaluated using the cone calorimeter following ASTM E 1354.0. Results show that tracking performance improves by 42.7% and 58.6% in S1 and S2 relative to S0 and it is improved by 27.7% in S2 compared to S1. Furthermore, S1 and S2 offer 33% and 46% more reductions in peak heat release rate (PHRR) than S1, while S2 offers a 20% better reduction in PHRR than S1. The high fire performance index (FPI) and low fire growth index (FGI) of S2 also indicate its enhanced combustibility resistance.