Dipole Orientation in Cable-Insulating Oils

A definite deviation from the Eyring behavior (in fm/T ¿ 1/T) is found to occur with cable-insulating oils studied over the frequency range extending from 30 Hz to 100 MHz at temperatures between -80° and 27°C. The obtained activation parameters of dipole orientation in the oils exhibit a marked temperature dependence. The results indicate that changes occur in the dipole relaxation mechanism with temperature, and that dipole orientation involves an appreciable rearrangement of the molecules in the neighborhood of the rotating dipoles.