Natural Ester | Paper | Standard | Temperatures | Duration | Results |
Palm kernel oil alkyl ester (PKOAE) [14] | TUK paper 0.255 mm thickness | ASTM D149 | 150˚C | 672, 1344 and 2016 h | Breakdown strength (BDS) of TUK dipped in MO is comprised between 55 and 54 kV/mm, while the BDS of TUK dipped in PKOAE is comprised between 78 and 75 kV/mm. |
Not specified [16] | Kraft paper 0.5 mm thickness | ASTM D149 | 110˚C, 140˚C, 160˚C and 185˚C | 336 h at 110˚C, then 336 h and 140˚C, next 336 h at 160˚C, finally 336 h at 185˚C for a total of 1344 h | Initial BDV of fresh paper equal to 4 kV. At the end of the aging tests, BDV of paper dipped in natural ester was the highest (16 kV), followed by paper dipped in synthetic ester (12 kV) then a mixture of mineral oil and synthetic ester (10 kV). |
Soya bean oil [17] | TUK and Nomex-910, each of 0.077 mm thickness | ASTM D149 | 120˚C, 150˚C and 180˚C | 48, 72 and 96 h | Initial Breakdown strength (BDS) of NP-910 equal to 92 kV/mm and TUK 62 kV/mm. After 180˚C after 96 hours, the BDS of Nomex-910 falls by 37.83, while the BDS of TUK falls by 52%. |