‘D.c. transmission systems’ covers the operational characteristics and equipment from the sending end a.c. system to the receiving end a.c. system, and includes the characteristics of those two a.c. systems as well as all the equipment in between. Since d.c. transmission is the ‘challenger’ and a.c. transmission is the ‘sitting tenant’ it behoves d.c. to prove its worth using the well-developed a.c. technique as a yardstick with regard to technical excellence, performance, reliability and the all important cost. Existing schemes are reviewed in terms of the system parameters which influenced the choice of d.c. and bulk long-distance transmission is used as an example. Control of a d.c. scheme is touched upon, followed by a discussion of some recent studies and operating experience.
