Development of a Relay Protective System On the Lines of the Southern California Edison Company, Ltd.

A record of the application of protective relays on the system of the Southern California Edison Company, Ltd., is presented. The history of this development of the protective relays in the 220-kv. transmission line, together with the results of the application of protective relays is recorded. In view of the limited application of carrier current protection, considerable discussion is presented covering its application on a section of the 220-kv. transmission system. Allied considerations pertaining to system stability on the 220-kv. system are discussed, and the rearrangement of the 66-kv. system as a means of improving system stability is also presented. In the interest of improving service, certain changes on the lower voltage 16-kv. and 11-kv. systems have been made.