Dielectric and Partial Discharge Properties of Insulating Rapeseed Oils

This paper presents basic dielectric properties of a type of insulating rapeseed oil, including its breakdown voltage, relative permittivity, and dissipation factor. Inception voltages of partial discharges (PD) occurring in this type of insulating rapeseed oils are also presented. PDs in insulating rapeseed oils are not only detected by the pulse current method recommended by IEC 270, but also observed by a camcorder capable of observing corona. Experiment results of insulating rapeseed oils and insulating mineral oils are presented for comparison. Partial discharge inception voltages of insulating rapeseed oils are about 3.5 kV higher than insulating mineral oils. The observation results of corona camcorder also show that number of photons, generated by PDs in the insulating rapeseed oils, is greater than that in the insulating mineral oils under the same test voltage.