The determination of the evolution of gas dielectric standard capacitor over the frequency range from 1 mHz to 20 Hz

A measuring procedure for determining the capacitance and the dissipation factor of low-loss capacitors over the frequency range from 1 mHz to 20 Hz is described. The determination of the correction factors due to the imperfection of the different elements used in the measuring circuit is also examined. The principle is to measure the absorption current of the capacitor due to a step voltage by an integrating method. The accuracy of measurement is expected to be a few PPM at 1 mHz.<>