Getah silikon merupakan salah satu contoh bahan polimer yang digunakan sebagai bahan penebat pepejal di dalam pelbagai aplikasi voltan. Walau bagaimanapun, jika tekanan yang berterusan diberikan, ia boleh menyebabkan kerosakan. “Electrical trees” merupakan contoh punca kepada fenomena pra-kegagalan yang berlaku di dalam penebat bervoltan tinggi. Selain itu, kehadiran cemar konduktif akan menggalakan pertumbuhan “Electrical trees”. Oleh itu, dalam projek ini persediaan eksperimen untuk siasatan “Electrical trees” terhadap SiR dibangunkan. Susunan radas terdiri kepada dua bahagian; bahagian voltan tinggi dan sistem pemantauan. Dua jenis sampel ujian iaitu SiR dan SiR dengan pencemaran telah disediakan dalam bentuk spesimen acuan. Pencemaran dengan saiz tetap telah disuntik dalam SiR untuk memerhatikan tingkah-laku “Electrical tree”. Voltan ditingkatkan secara perlahan-lahan sehingga “Electrical trees” mula tumbuh di hujung jarum dan nilainya dicatatkan sebagai “treeing initiation voltage” (TIV). Kemudian, nilai voltan dinaikan sehingga 8 kV dan dibiarkan selama 20 minit. Fenomena “Electrical trees” dirakam dan panjang “Electrical trees” diukur dengan menggunakan kamera digital dan stereomicroscope. Hasil penyiasatan menunjukkan, nilai TIV untuk kedua-dua jenis sample adalah sama. SiR dengan pencemaran menunjukkan kecenderungan “Electrical trees” untuk tumbuh ke arah pencemaran. Terdapat empat jenis “Electrical trees” yang terbentuk semasa kajian dijalankan; branch, bush, pine and mixed. Diantara kempat-empat jenis ini, bush mempunyai pertumbuhan yang baik kerana ia mengalami proses “stagnation period” yang lama.
_______________________________________________________________________________________________________
Silicone rubber (SiR) is one of the example polymeric material that has been used as solid insulation material in various range of voltage application. However, as continuous stress is given to polymeric material, it may lead to a formation of electrical treeing. Electrical treeing is recognized as one of the pre-breakdown phenomena that occurs in high voltage (HV) insulation material. Besides that, the presence of defect in insulation material such as conductive contaminant will enhance the growth of tree structure. Thus, in this project the experimental setup for investigation of electrical treeing in SiR was developed. The arrangement of apparatus consists of two parts; HV part and live monitoring system part. Two groups of test samples such as SiR and SiR with contamination were prepared in mold specimen. The contamination with fixed size was injected inside SiR to observe the behaviour of treeing. The applied voltage was increased slowly until the tree start to initiate from needle tip and the voltage was recorded as tree initiation voltage (TIV). Then, the voltage was increased until 8 kV and was keep constant for 20 minutes. Treeing growth was recorded and the length of tree was measured by using digital camera mounted on stereomicroscope. The result shows, SiR and SiR with contamination sample have same value of TIV. The tendency of tree growth in SiR with contamination shows the tree tend to grow towards the contaminant. There are four type of treeing that formed during the experiment; branch-type, bush-type, pine-type and mixed-type. Among the four types, bush-type has the shortest electrical tree because it undergoes stagnation stage for a long period.
Development of experimental setup for investigation of electrical treeing characteristics / Muhammad Adli Syafiq Khairuzaman