Low-Voltage D-C Measurements on Electrical Insulating Oils

1. Apparatus has been developed which is suitable for the measurement at low voltages of the d-c conductances of electrical insulating oils. 2. The change of d-c conductance with time of a highly refined oil has been found to substantiate the theory. that low-voltage methods do measure the true d-c conductance of electrical insulating oils. 3. The change in the conductance of this oil is shown to be a function of VXt, V being the applied voltage, and t the length of time of application. 4. D-c measurements have been compared with a-c measurements on a low-viscosity oil and low-voltage d-c measurements have been shown to account for all of the a-c loss in the oil thereby again leading to the conclusion that the low-voltage methods developed in this paper do measure the true d-c conductance of electrical insulating oils.