An improved model of mutual admittances of tapped windings

The calculation of the equivalent admittances of windings tapped in sections, which are used as elements of high-accuracy measuring instruments (e.g., in inductive voltage dividers, magnetic current comparators, and transformers with minimum ratio errors), is considered. A comprehensive mathematical model of equivalent admittances is presented. It is derived from the measured mutual admittances of particular sections. The equivalent admittances of this model are dependent on the actual values of the mutual admittances as well as on the actual tap voltages. With the equivalent admittances it is possible to analyze, in a simple way, the ratio errors and the input admittance due to parasitic admittances and to calculate the accurate values of correcting admittances.