Synchronous machines are principally used as alternating current generators. They supply the electric power used by all sectors of modern society. Synchronous machine is an important electromechanical energy converter. Synchronous generators usually operate in parallel forming a large power system supplying electrical power to consumers or loads. For these applications the synchronous generators are built in large units, their rating ranging form tens to hundreds of Megawatts.
The excitation system on a AC alternator refers to the way the alternators voltage is initially built when rotated and controlled while in use. The excitation system is responsible for supplying the field current to the main rotor. The requirements of an excitation system include reliability under all conditions of service, a simplicity of control, ease of maintenance, stability and fast transient response. There are three main types for standard brushless self excited machines. You may also see transformer controlled alternators. Each system has advantages and disadvantages, meaning the preferred option is based on the applications requirements and budget. An auxiliary wound AC alternator in addition has a auxilliary winding embedded in the main stator.
Post a comment. Most alternators have the rotating field and the stationary armature. The rotating-field type alternator has several advantages over the rotating-armature type alternator. This generated voltage may be as high as 33 kV. Usually the field voltage is between to volts.
Basically, an AC generator is an electrical machine that converts mechanical energy into electrical energy in the form of Alternating Current AC. Basic principle behind the working of an AC synchronous generator is also Faraday's law of electrical induction , somewhat similar to working of a DC generator. The above figure illustrates how an alternator or AC synchronous generator work.