A new carrier relaying system

IT has long been realized that the surest and most effective way to obtain simultaneous breaker operations at both ends of a transmission line, regardless of the location of a fault within the line section, is by use of some form of pilot channel relaying. Two forms of this type of protection have been developed and used very successfully for a number of years. One system is the familiar distance-type carrier relay system, and the other is the single-element differential pilot-wire system.