ABSTRACT
The backbone of any electric power system is a number of generating stations operating in synchronism. At each station there may be several synchronous generators operating in parallel. Synchronous machines represent the largest single-unit electric machine in production. Generators with power ratings of several hundred to over a thousand megavoltamperes are fairly common in many utility systems. A synchronous machine provides a reliable and efficient means for energy conversion. The operation of a synchronous generator is based on Faraday's law of electromagnetic induction. The term synchronous refers to the fact that this type of machine operates at constant speed and frequency under steady-state conditions. An understanding of the nature of the magnetic field produced by a polyphase winding is necessary for the analysis of polyphase ac machines. Field poles in a salient-pole machine cause nonuniformity of the magnetic reluctance of the air gap. The reluctance along the polar axis is appreciably less than that along the interpolar axis.
