Penyeberang penghubung polietilena (XLPE) adalah sejenis bahan penebat yang kukuh untuk pelbagai julat applikasi voltan. XLPE telah dibangunkan pada tahun 1963 untuk menggantikan kabel kertas plumbum terlindung (PILC) kerana banyak kes-kes kerosakan berlaku. Di Malaysia, XLPE digunakan secara meluas oleh Tenaga Nasional Berhad (TNB) dari tahun 1980 sehingga sekarang. Walaupun kelebihan XLPE, kerana tekanan yang berterusan diberikan kepada bahan polimer, kehadiran “electrical tree” membawa kepada kerosakan penebat. “Electrical tree” ialah fenomena pra-kerosakan yang berlaku dalam
voltan tinggi (HV) bagi bahan penebat. Apabila tekanan voltan tinggi berterusan digunakan kepada XLPE, penebat akan mengalami kerosakan seiring dengan waktu dan membawa kepada “electrical tree”. Oleh itu, projek ini dilakukan untuk membangunkan persediaan eksperimen bagi menyiasat “electrical tree” pada XLPE berumur dan XLPE tidak berumur
serta mengkaji ciri-ciri “electrical tree” akibat tekanan elektrik yang tinggi dalam XLPE berumur dan XLPE tidak berumur sebagai bahan penebat bagi penggunaan kabel 11kV. Dua kumpulan sampel; XLPE berumur dan XLPE tidak berumur telah diuji. Voltan yang tinggi digunakan untuk setiap sampel dengan kenaikan sebanyak 1kV dan 1 min masa rehat
sehingga “electrical tree” terhasil di hujung jarum. Voltan tidak diubah pada permulaan voltan bagi “electrical tree” (TIV) sehingga pertumbuhan sebnyak 1.2 mm dari hujung jarum. Pertumbuhan “electrical tree” dan kepanjangan dicatatkan dan diukur menggunakan sistem pemantauan dalam talian semasa ujian. Berdasarkan keputusan, TIV bagi XLPE berumur dan
XLPE tidak berumur tidak mempunyai banyak perbezaan. Terdapat tiga jenis struktur “electrical tree”; dahan,batang dan tidak berkembang. Masa bagi pertumbuhan “electrical tree” XLPE berumur adalah berbeza dengan XLPE tidak berumur.
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Cross linked polyethylene (XLPE) is a type of solid insulation material for various ranges of voltage application. XLPE have been developed in 1963 to replace the paper insulated lead cable (PILC) due to a lot of breakdown cases occurred. In Malaysia, Tenaga Nasional Berhad widely used XLPE from 1980 until present day. Despite the merit of XLPE, as continuous stress is given to polymeric material, an electrical treeing appears that lead to insulation breakdown. Electrical tree is a pre-breakdown phenomena that occurs in high voltage (HV) insulation material. When a continuous high voltage stress is applied to XLPE, the insulation will degradate across time and leads to electrical treeing. Therefore, this project is done to develop the experimental setup to investigate the electrical tree of aged XLPE and un-aged XLPE and to study the electrical tree characteristics due to high electrical stress in aged XLPE and un-aged XLPE as insulating material for the 11kV cable application. Two groups of samples; aged XLPE and un-aged XLPE were tested. The high voltage is applied to each sample with an increment of 1kV and 1 min rest time until electrical tree initiate at the tip of the needle. The voltage is kept constant at the tree initiation voltage (TIV) until the electrical tree growth length is 1.2mm from the needle tip. Electrical tree growth and length are recorded and measured using on-line monitoring system during the testing. Based on the results, TIV of aged XLPE and un-aged XLPE are most likely. There are three types of electrical tree structures evolved; branch-like, vine-like and stagnated tree. The electrical tree growth time for aged XLPE are in contrast with un-aged XLPE.
Electrical tree characteristic of aged and un-aged of XLPE as insulating material for 11KV cable application / Nur Alia Mohd Yusoff