Page 43 - Practical Power System and Protective Relays Commissioning

Generators and Motors: Theory and Testing Chapter | 4 39

used excitation system for generator is the brushless excitation system con-
sists of the following components:

Pilot exciter
Main exciter
Rectifier wheel
Automatic voltage regulator
In a brushless excitation system a rectifier is mounted on the rotor. The
emf induced in the three-phase rotor winding of the main exciter is rectified
and supplied to the DC field winding of the main generator on the rotor as
shown in Fig. 4.8.
This system does not need slip rings and brushes. It has the main exciter
on the main shaft of the generator-turbine with a rotating rectifier and pilot
exciter of permanent magnet generator as shown in detail in Fig. 4.9.
This system provides the main generator with a direct current for field
winding and controls this current based on the generator output voltage. The

FIGURE 4.8 Brushless excitation system.