ABSTRACT
Modern general-purpose computer programs are available for calculating the magnetic field inside the complex geometry of a transformer. This chapter presents Rabins' method and explores how it can be used to obtain the leakage magnetic field, forces, leakage inductances, and mutual inductances between coil sections, for use in detailed circuit models of transformers such as those needed in impulse calculations. It establishes a model of a cylindrical coil or section of a coil surrounding a core leg with top and bottom yokes. The leakage inductance for a two-winding transformer can be obtained from the total magnetic energy, when there is amp-turn balance. The chapter expresses that the Rabins' method inductances tend to give good agreement with impulse data obtained via recurrent surge oscillograph, RSO methods. Determining the B-field within the windings is important in order to obtain the electromagnetic forces acting within the windings as a result of a fault and associated high-winding currents.
