Abstract:
The classic arrangement of a direct driven d.c. exciter has proved, in general, a reliable, economic and 'satisfactory source of excitation supply for turbogenerators of moderate output. With increasing rating of individual units, the excitation power required exceeded that practicable- for a direct coupled d.c. machine and gearing was introduced to permit operation at a lower speed. These two factors, higher output and- lower speed, inevitably resulted in greater physical size, with problems of access for maintenance purposes. Econo-
mics dictate that larger base load units should operate for the maximum period between planned shut down and provide a stimulus to develop alternative sources of excitation power. The rotating field a.c. exciter with static rectifier has been
extensively adopted. Ot ler excitation, schemes are in use only on smaller units or on special or prototype machines.
In' this thesis, a critical uptodate literature review of the different excitation schemes has been done. Application of probability techniques is made for reliability assessment. of different excitation systems. Different possible alternative designs have been considered and the reliability analysis of these design alternatives has also been done. At last, a comparison of the basic system and the different design configurations has been made from reliability point of view in a tabular form.
