Dielectric properties of fullerene-doped insulation liquids

The work presents the concept of C₆₀ fullerene nanomodification of mineral insulation oil. For the research, 20 probes of oil were prepared; one pure and 19 containing different content of C₆₀ - from 1 mg/1 to 512 mg/1. The probes were examined mainly against their tendency to electrification. To control if fullerene modifications do not deteriorate other parameters, the electrical endurance, permittivity, dielectric loss tangent and resistivity were also measured. The electrification current was measured using rotating electrometer spinning disk system developed in the institute where authors of the paper work. The current was measured for rotational speeds from 0 rpm to 400 rpm. The research revealed the C₆₀ ability to significantly reduce the constant component of streaming electrification current. It is possible to determine the C₆₀ concentration optimal for the whole rotational velocities range analyzed. For maximal electrification current reduction one may also optimize the C₆₀ content for a specific flow velocity, as the concentration giving the minimal current value depends on velocity. By doping with C₆₀ fullerene, dielectric loss tangent reduction by more than 30% is possible for the similar range of C₆₀ concentrations that give the optimal electrification current values. All C₆₀-doped probes examined had breakdown voltage at the same or higher level than the pure oil. The resistivity and permittivity do not depend on C₆₀ content. The research proves the C₆₀ is able to significantly improve some essential dielectric properties of mineral insulation oil, without deteriorating the others.