From the Preface: To understand and to solve the problems of the converter supply situation, a thorough knowledge of electrical machines in the conventional supply conditions is indispensable. To this knowledge the book will contribute by reviewing the strong and the weak points of the most efficient a.c. and d.c. machines,and by clarifying the consequences of 100 year partnership between a.c. rotating-field machines and alternating-current supplies. For this, an inside-oriented description of electrical machines, using airgap-referred specific quantities, presented already in an earlier text has proven to be of great help, and has been further developed in this book.