Ciri-ciri penuaan kertas penebat transformer Kraft di dalam minyak ester minyak kelapa dara (VCO) pada kelembapan yang berbeza dibandingkan dengan ciri-ciri penuaan kertas penebat transformer Kraft di dalam minyak mineral (MO), juga, pada kelembapan yang berbeza. Tujuan kajian ini adalah untuk mengkaji kesan kelembapan pada minyak ester VCO dan minyak transformer konvensional MO pada tahap penuaan yang berbeza. Proses penuan Kertas penebat Kraft dan cecair dielektrik, VCO dan MO, dilakukan pada suhu 90 ° C selama 0, 168, 336, dan 504 jam pada tahap kelembapan yang berlainan. Dalam kajian ini, sampel minyak VCO dan MO disediakan dalam lima keadaan kelembapan yang berlainan, 0 ppm, 10 ppm, 30 ppm, 100 ppm dan keadaan kelembapan ‘Bekas Simpanan’. Untuk ujian kondisi kering, sampel kertas Kraft disediakan untuk ujian ukuran kerosakkan voltan dan ujian kekuatan tegangan. Selain itu, untuk ujian “in-oil”, sampel kertas Kraft telah direndam dalam sampel cecair dielektrik yang diuji untuk ukuran kerosakkan voltan dan ujian kelikatan. Voltan kerosakan VCO dan MO telah diuji dengan “oil test unit” dan kerosakan voltan kertas penebat Kraft juga diuji menggunakan “in-oil breakdown strength test unit”. Kajian ini menunjukkan, sampel VCO menunjukkan perubahan warna minimum berbanding sampel MO, berdasarkan “American Standard of Testing and Materials” (ASTM) D1500. Kekuatan tegangan kertas diuji menggunakan “Single Column Universal Test Machine” dengan kapasiti kekuatan 500N. Berdasarkan keputusan yang diperolehi daripada ujian tersebut, kekuatan pecahan minyak ester VCO hamper 50% lebih tinggi berbanding MO. Kelikatan VCO adalah dua-kali ganda lebih tinggi berbanding MO. Keputusan daripada uji-kaji proses penuaan, kelikatan dikatakan hampir tidak berubah untuk MO and VCO. Kehadiran kelembapan dalam VCO tidak menjejaskan sifat dielektrik VCO berbanding MO. Sampel kertas Kraft yang diresapi dalam VCO menunjukkan ukuran kerosakkan voltan hamper 50% lebih tinggi berbanding dengan sampel kertas Kraft yang diresapi dalam MO. Selain itu, sampel kertas penebat Kraft yang diresapi dalam VCO menunjukkan pengekalan kekuatan tegangan hamper 90% berbanding MO hanya 50% sepanjang tempoh penuaan. Ukuran kerosakkan voltan VCO dan kertas Kraft yang diresapi VCO didapati, secara purata, lebih baik daripada MO dan kertas Kraft yang diresapi MO.
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The ageing behaviour of Kraft transformer insulating paper in natural ester virgin coconut oil (VCO) at different moisture was compared with the ageing behaviour of Kraft transformer insulating paper in mineral oil (MO), also, at different moisture. The aim of the study is to investigate the effect of moisture in natural ester VCO and the transformer MO at different ageing level. The Kraft paper and the dielectric fluid, natural ester VCO and petroleum-based MO, were aged at 90C for 0, 168, 336, and 504 hours at different moisture level. In this research study, the oil samples of VCO and MO were prepared with five different moisture condition in which, 0 ppm, 10 ppm, 30 ppm, 100 ppm and out-of-container moisture condition. In dry condition test, the sample of Kraft insulating paper were prepared for breakdown strength and tensile strength test while for in-oil test, the samples of Kraft paper were immersed in VCO and MO for breakdown strength and viscosity test. The breakdown voltage of the VCO and MO were tested with the oil test unit and the breakdown voltage of the Kraft transformer insulating papers were also tested using in-oil breakdown strength test unit. This research found that, the samples of VCO show minimal color change as compared to samples of MO when tested according to America Standard for Testing and Materials (ASTM) D1500. The tensile strength of the paper were tested using Single Column Universal Test Machine with force capacity of 500N. The results obtained from this test found that, breakdown strength of natural ester VCO is almost 50% much higher compared to petroleum-based MO. Indeed, viscosity of VCO is also twice as higher than MO. This experiment findings also show that after the ageing process, the viscosity is said to be almost constant for both MO and VCO. The presence of moisture in VCO doesn’t affects the dielectric properties of VCO as compared to MO. The samples of Kraft insulating paper impregnated in VCO show almost 50% higher breakdown strength as compared to samples impregnated with MO. Moreover, the samples of Kraft paper impregnated in VCO show better tensile strength retention with 90% tensile strength retention as compared to MO only 50% over ageing period. The characteristic breakdown strength of VCO alone and VCO impregnated paper was found to be, on the average, better than that of MO alone and MO impregnated paper.
Insulating paper – natural ester insulation oil characteristics at different moisture and ageing level / Muhammad Fariz Ahmad Shukri