Characteristics of partial discharge and time to breakdown of nanocomposite enameled wire

The insulation properties of nanocomposite enameled wire, in which nano-sized inorganic material such as layered silicate is used as an additive component, have been investigated. An extraction of SiO₂ at the surface of the nanocomposite enameled wire was observed after the voltage life test by using Fourier transform infrared spectroscopy. This result suggests that the inorganic material remains after evaporation of the organic material due to partial discharge (PD) at the surface. It could be considered that the inorganic material protects the enameled wire from physical sputtering of PD charges. A technical improvement of the twisted pair configuration was proposed to prevent the concentration of PD activity at the edge of the twisted pair when the applying voltage is around the PD inception voltage. It was found that PD charge in the case of nanocomposite enameled wire is reduced when the applying voltage is the same in comparison with the conventional one. It could be considered that the SiO₂ layer on the insulating material and the decreased PD charge could play a major role for the superior insulating properties of the nanocomposite enameled wire.