Excitation (magnetic)

An exciting machine is an electric machine that generates the electric power, which is necessary in order to supply the field winding of a generator with a current. The power control for the generator in either the exciter or between it and the generator is realized. Alternators are energized with a direct current field. Previously, the exciter was therefore a direct-current machine; Today, she is a three-phase machine with downstream semiconductor rectification.

In order to reduce the carbon brushes and slip rings for static excitation systems for the transfer of excitation energy to the rotor winding ( exciter coil ) are necessary and exciter rotor are placed on the same shaft. This is the principle of brushless excitation. The big advantage here is that no moving wear parts are no longer present. The exciter is a rotor machine ( Außenpolgenerator ) which has its field windings in the stator and generates the induced voltage in the rotor. By firmly in the rotor rotates with built-in diode rectifier voltage is rectified and applied to the field winding in the rotor of the generator. The output of the generator can be tapped at the terminals of the stator windings. In this embodiment, the control is already on the exciter field. For this purpose, the auxiliary excitation power, with the outer poles of the exciting machine are fed, controlled by an actuator. The disadvantage here is that the achievable temporal changes ThE / dt by the time constant of the exciter machine is reduced. The rise times for interference are therefore greater than with static excitation systems.

Yellow Front right cubical housing, exciter of the brushless exciter device; behind the turbo generator, yellow cylindrical unit in the center; then the multi-level, blue -painted steam turbine

Synchronous generator in the square red painted housing with brushless excitation device; Exciter with permanent magnet excitation right flanged to the housing; in the stainless steel pipes, the oil lubrication; in the green lines, the glycol cooling with internal air circulation