CHAPTER 31 SYNCHRONOUS GENERATORS

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SYNCHRONOUSGENERATORSSynchronous generatorsoralternatorsare SYNCHRONOUS machines that convert mechanicalenergy to alternating current (AC) electric GENERATOR CONSTRUCTIONA direct current (DC) is applied to the rotor winding of a SYNCHRONOUS generator to producethe rotor magnetic field. A prime mover rotates the generator rotor to rotate the magneticfield in the machine. A three-phase set of voltages is induced in the stator windings by therotating magnetic rotor is a large electromagnet. Its magnetic poles can be salient(protruding or stickingout from the surface of the rotor), as shown in Fig. , or nonsalient(flush with the surfaceof the rotor), as shown in Fig. Two- and four-pole rotors have normally nonsalientpoles, while rotors with more than four poles have salient generator rotors are constructed of thin laminations to reduce eddy current losses,while large rotors are not constructed from laminations due to the high mechanical stressesencountered during operation.

without any external electric power (Fig. 31.5). Most synchronous generators that have brushless exciters also use slip rings and brushes as an auxiliary source of field DC current in emergencies.

  Electric, Power, Generators, Synchronous, Electric power, Synchronous generators