This book is a result of the author's work which was initiated about a decade ago and which, in the meantime, has resulted in his Ph.D. Thesis and several technical papers. The book deals with accurate modeling of electric machines during transient and steady states, a topic which has been usually avoided in the literature. The modeling techniques herein take into account all machine peculiarities, such as the type and connection of its windings, slotting, and saturation in the iron core. A special emphasis in the book is given to the exact physical interpretation of all phenomena which influence the machine's transient behavior. Besides the Introduction, the book has five chapters. The second chapter describes basic concepts of the magnetic equivalent circuit theory and has examples of magnetic equivalent circuits of several types of machines with their node potential equations. In the third chapter the transform matrices w' and w" of A.C. wind­ ings are derived. These matrices playa very important role in the magnetic equivalent circuit theory because they connect the quantities from the ma­ chine's magnetic equivalent circuit, branch fluxes, and mmfs with the ma­ chine's phase currents and fluxes.