Partial discharge characteristics and dissolved gas analysis of vegetable oil

Abstract

Vegetable oil is considered as biodegradable insulating oil alternative recently. Palm fatty acid ester (PFAE) oil and 2H-O8 oil are palm based vegetable oil that have been considered as insulating oil. This paper discusses PFAE oil and 2HO8 behavior due to partial discharge (PD) occurrence compared to mineral oil. The comparison includes PD repetition number n, average PD charge qav, and generated gases. In the first experiment, 10 kV to 20 kV step voltages are applied to the insulating oil for 120s each step. n and qav are measured. In the second experiment, 17 kV is applied to the insulating oil for 2 hours and generated gases are measured after that. The results show that n and qav of mineral oil are less than PFAE and 2H-O8 oil. Mineral oil has an ability to suppress bubble diffusion better than PFAE oil and 2H-O8 oil due to its higher kinetic viscosity number. Accumulative PD charge in PFAE oil and 2H-O8 oil is much higher than mineral oil and generates more gases, especially H₂. For a single PD charge, mineral oil generates more H₂ than PFAE oil and 2H-O8 oil. Mineral oil has more C-H bond which is dissociated in lower energy. For certain ageing time, mineral oil gives better performance regarding to PD occurrence than PFAE oil and 2H-O8 oil.