This text is an introductory treatment of modern electromechanical devices that prepares the reader with the basis to study and understand the emerging applications of electric machines in the emerging smart grid. It especially covers modern electric drive applications, while also satisfying the power system interest. Teslas rotating magnetic field, which is the foundation of reference frame theory, is covered extensively in Chapter 4. This sets the stage for reference frame theory, which is covered in Chapter 5. The permanent magnet ac, synchronous, and induction machine are covered, respectively, in Chapters 6, 7, and 8. In each chapter, the material is arranged so that if steady-state operation is the main concern, the reference frame derivation can be de-emphasized and focus placed on the steady state equations that are similar in form for all machines.