Impact of accelerated ultraviolet weathering on polymeric composite insulators under high voltage DC stress

This work investigates the weatherability of room temperature vulcanized (RTV) silicone rubber (SiR) and epoxy-based materials specimens with a composition of different nano and micro fillers against the collegial effects of high voltage DC, UV and temperature stresses. Bulk power transmission over long distances via HVDC is considered an economic option these days, so to ensure the system reliability it is also critical to investigate these insulators under DC stress along with other environmental stresses (especially UV and temperature). For experimentation, composite samples i.e. neat epoxy (NE), epoxy with 15% micro SiO2(EMS), epoxy with 5% nano SiO2(ENS), neat SiR (NS), SiR with 15% micro SiO2(SMS) and SiR with 5% nano SiO2(SNS) are fabricated and subjected to accelerated aging in the weather chamber for 3360 hours. Results revealed that SMS and SNS offered better hydrophobic behavior followed by EMS. However noticeable surface discoloration in the form of whitish shade with minor blackish spots is found in the case of SMS, while remaining samples also showed considerable color fading. Scanning electron microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) results showed that SNS and SMS presented quite excellent resistance to the exposure of fillers. Hardness and weight of all specimens are evaluated throughout the experiment and particularly for water immersion test. Moreover, leakage current analysis proclaimed that SNS and SMS revealed high leakage current suppression compare to other samples. Findings indicate that SNS and SMS showed enhanced resistance against UV weathering under high voltage direct current stress.