Dielectric properties of palm oils as liquid insulating materials: effects of fat content

For transmitting a huge amount of electric power, transformer is one of the most important apparatuses. Liquid insulating materials are usually used in medium as well as high voltage transformers. Since long ago, petroleum-based mineral oils have been used as liquid insulating materials. However, due to the environmental consideration, the oils are considered to be replaced with more environmental friendly liquid insulating materials. Many researchers are now searching new types of insulating materials, which are generally organic types and obtained from the nature. The new insulating materials are biodegradable and friendly to environment. In attempt to find the new type of liquid insulating materials, we have investigated the dielectrics properties of palm oil. The samples used are RBDPO (refined, bleached and deodorized palm oils) with various content of fat (lipid). The losses factors and breakdown voltages of the oils as function of temperature and fat content were investigated. The values of flash point and viscosity as function of temperature and fat content are presented. The dependences of oil properties on the fat content were investigated. The experimental results showed that the fat content strongly affected the dielectric properties of the oils. In general, the dielectric properties improved as the fat content is reduced. The dielectric strength increased significantly as the fat content dropped to about 1 %.