Dielectric admittances in current transformers

The ratio of a current transformer having appreciable capacitance between windings is dependent upon whether and how the windings are connected together. There are five ratios which may be defined without a knowledge of the external circuits, one of them without any direct link between windings and four with a low-resistance link between one primary terminal and one secondary terminal; only two of these ratios may be measured directly by a simple bridge. Formulae are developed in the paper by means of which all the ratios may be deduced from simple bridge measurements; the adequacy of the formulae is tested by experimental measurements. A simple test is developed for determining quickly whether the effect of capacitance is appreciable in a transformer of unknown characteristics, and methods of construction of low-capacitance transformers are discussed.