We begin this tutorial with an introduction to the principles of motor speed control. We then follow with the basic elements of the power electronic circuits and devices which are used in ASDs. Then comes a discussion of the application of ASDs in electric utilities which includes examples of utility experience. Different types of drives are then discussed along with harmonic production. After these introductory sections, we focus on the applicationn of ASDs to motors. A general introduction of MMF and torque production is followed by the analysis of adjustable speed synchronous and induction motors. Application considerations of interest to utility engineers are then discussed. The important area of direct current machines follows and we end with a discussion of advanced research in motors and drives with an emphasis on modeling.