The measurement and calculation of axial electromagnetic forces in concentric transformer windings

An experimental method of determining the axial forces in power transformers is applied to a transformer constructed so that various tapping arrangements can be set up, and curves are given of the forces which occur with typical methods of tapping concentric windings. It is considered that the simple ¿residual ampere-turn¿ method of calculating axial forces is sufficiently accurate for design purposes, and a number of formulae are given which should cover most of the requirements of the transformer designer. The distribution of axial force around the periphery of the coils is investigated experimentally.