4 - Introduction to Electric Machines

Abstract

This chapter provides an introduction to electric machines. Essentially all electric energy is generated in a rotating machine, the synchronous generator, and most of it is consumed by electric motors. The study of the behavior of electric machines is based on three fundamental principles: Ampère's law, Faraday's law and Newton's Law. Various configurations result are classified generally by the type of electrical system to which the machine is connected: direct current (dc) machines and alternating current (ac) machines. Machines with a dc supply are further divided into permanent magnet and wound field types. The wound motors are further classified according to the connections used. The field and armature may have separate sources (separately excited), they may be connected in parallel (shunt connected), or they may be series (series connected). Machines that have ac are usually single-phase or three-phase machines and may be synchronous or asynchronous. This chapter discusses briefly the basic principles on which all standard electric machines operate and then, for the most common devices, explains the principles of operation.