Signal and Supervision Systems Used on Carrier Current Communications Circuits

During the past few years there have been numerous systems of supervisory control and coded digital selectors designed and described in various papers. These systems, as a whole, have been designed for specific use as power-supervisory control units, or as commercial-telephone circuit-switching and trunking assemblies. The purpose of this paper, however, has been to discuss some signaling and supervisory-trunking systems used in conjunction with the normal operation of a large power utility. It has further been desired to illustrate these systems as they are applied to carrier-current systems and mediums of transmission.