Power-line carrier for relaying and joint usage — II

IN ANALYZING the relaying techniques involved in this subject, as distinct from the carrier tools available, we find that there are three recognized principles of carrier relaying, namely: 1. transferred signals, 2. phase comparison, and 3. directional comparison. Any of these principles must be applied with attention to the local conditions under which it must function. By inattention to detail design, trip and control circuits have been known to hold lines, equipment, or protection schemes out of service unnecessarily. Also, the operating personnel may have numerous special features to remember and watch. Such instances, plus random difficulties, can build up antipathy to any type of relaying, carrier included.