An excitation system is a means to provide regulated DC current to the field windings of a generator, to produce an output voltage to the field. The generator is used to turn mechanical energy from a prime mover into electrical energy for transmission to customers. The prime mover - which may be a hydro, gas, steam, or wind turbine - controls the megawatt load of the generator.
The generator’s armature (or stator winding) is stationary and carries the output power of the generator to the step-up transformer. The generator’s rotor fits into the center of the armature and the field winding is attached to the rotor. It carries the current supplied by the excitation system to excite the generator.
All electrical generators require excitation to create electrical energy. The excitation system excites the armature by creating a magnetic field on the rotor via a DC current. The output voltage of the armature varies with the strength of the magnetic field.
Thus, the excitation system controls the output voltage of the generator by adjusting DC current to the generator field winding. Excitation systems have two general classifications - rotating exciters or static exciters.
Rotating exciters include brushless and brushed types, and typically have the following characteristics:
Static Exciters include compound sources and potential sources, and have different characteristic than rotating exciters:
Emerson provides our customers with excitation systems that are fully integrated or stand-alone, along with all the supporting software and field services. Visit our excitation system webpage to learn more.
