An attempt to compare the power supply configurations and their components with some useful but limited information for operational particle accelerators of 1950s has been briefly described in Chap. 3 . Such comparison was possible simply because the selected accelerators basically shared the similar design philosophy of power supply for magnet excitation. With the progress of time and advancement in science and technology, those accelerators were declared obsolete long back and replaced with the new forms of design. But, it left behind only heap of past experiences gained from outstanding research work in all fronts which ultimately remained as a guide book for the engineers and technologists to refer at the time of crisis in handling difficult problems. The strength from old expertise guided to steer the progress in the development of power supplies for magnet excitation in the right direction till date, helped to extract abundant benefits for the new schemes of accelerator projects developed at later stages. A long-awaited search for alternative schemes ultimately fulfilled the cherished dreams of improving accelerator performances and reducing cost of operation with the development of new technologies which particularly concentrated on the following areas: