The dielectric spectroscopy of new generation of transformer oil Shell

In this paper, are described experimental results of structural changes of investigated ferrofluids based on insulating oil produced by a gas-to-liquid process and containing ferrimagnetite nanoparticles. Compared to normal mineral oils on the paraffinic and naphthenic base, oils derived from GTL technology are purer and have a higher lightning impulse breakdown voltage. As a carrier liquid, transformer oil (Shell Diala S4 ZX-I) with a concentration of 0.98 % ferrimagnetite nanoparticles contains investigated ferrofluid. In this experiment, dielectric spectroscopy methods were applied to obtain experimental data to investigate structural changes in Shell transformer oil as a result of an external magnetic field applied to ferrofluid. The dielectric measurements were carried out at perpendicular and parallel orientation of the electric and magnetic fields, too, and in the frequency range from 1 mHz to 10 kHz. The magneto-dielectric effect of the dielectric losses was studied, too. The changes of dielectric parameters were measured also at the linear change of the magnetic field to values up to 200 mT and anisotropy measurement.