Abstract:
Currently, there are attempts to develop vegetable oils having biodegradability and non-toxicity to replace the use of the mineral oil. Palm-based oil (EnPAT) is one of the alternative vegetable oil which is developed as an insulating liquid for the transformer. While the transformer is operating, it has generated heat that affects the insulating liquid, and the insulating paper deteriorated. Therefore, this work focused on studying the characteristics of deterioration of palm-based oil with immersed paper insulation and compared to the mineral oil and a commercial natural ester (FR3) under thermal aging at 110, 130, and 150˚C for different times in a sealed system. After thermal aging under nitrogen atmosphere, the EnPAT deteriorated. The moisture content and acidity tended to be increased, which were similar to those of FR3, but it was higher than that of mineral oil. Whereas the magnitude of dissolved decay content was the lowest. Furthermore, the dielectric breakdown voltage of aged EnPAT was higher than aged mineral oil. However, after thermal aging at 150 ˚C for 2,880 and 4,008 h. the retained tensile strength of insulating paper immersed in EnPAT was clearly higher than that of immersed in the mineral oil. Moreover, after thermal aging at 150 ˚C for 720 h. under oxygen atmosphere, that all oils were severe deterioration. However, the aged EnPAT had the highest dielectric breakdown voltage.