A standard of low power factor

NEED of a suitable standard of low power factor for use in checking the accuracy of the various devices and bridges employed in the measurement of loss in dielectric samples is pointed out in this paper. The relative merits of the different methods that have been proposed for this purpose are discussed and then the low power factor standard which has been developed is described. This standard consists of a shielded and guarded air capacitor having in series with its guard and main circuits an ideally shielded resistor. The ideally shielded resistor is made up of 2 concentric resistances with the same value of resistance per unit length. The inner resistance is connected in series with the main electrode of the air capacitor, and the outer resistance, which shields the inner, is connected in series with the air capacitor guard. The use of this ideally shielded resistor in connection with the air capacitor makes it possible to have a zero potential difference at all points between the guard and the main electrode.