Study on Dielectric Properties of Natural Ester Based Synthetic Insulating Oil

Natural ester insulating oil, as a kind of environmentally friendly liquid dielectric with high ignition point, has been well used in engineering applications in distribution transformers. The frequency domain dielectric properties of an insulating oil can be reflected by its polarization, loss and other parameters and used to determine the dielectric strength of the oil. Dielectric properties are important properties for evaluating the insulating ability of the oil and determining whether the transformer can be operated reliably. In this paper, the effects of temperature and frequency on the dielectric properties of PCIE and MIDEL 7131 insulating oil are investigated, and the results show that the trends of the two with temperature and frequency are consistent. There are more asymmetric molecular structures in PCIE, the dielectric constant is slightly higher than that of MIDEL 7131, and the fluctuation of relaxation time by temperature is more obvious.