Читать книгу Alternative Liquid Dielectrics for High Voltage Transformer Insulation Systems - Группа авторов - Страница 35

The rapeseed oil or canola oil is extracted from the crude rapeseed oil after three refinement procedures, which are alkaline refinement, vacuum distillation, and bleaching [45, 46]. The basic attributes of the refined oil are shown in Table 2.2. The refined form of rapeseed oil exhibits lighter color, lower acid value, and enhanced electrical properties when compared with the crude form of the oil. The flash point of the rapeseed oil is above 300 °C, which is nearly twofold the flash point value of the conventional MO used in transformers. The dipolar characteristic of ester molecules produces higher values of dielectric permittivity (ε_r), and dielectric dissipation factor (tan δ ) of the insulating rapeseed oil than transformer MO.