Relays and breakers for high-speed single-pole tripping and reclosing

THE advantages of fast reclosing of transmission-line circuit breakers have been realized for a number of years. This experience has been gained on the basis of three-pole reclosures. One step beyond three-pole tripping and reclosure is single-pole operation. It is arranged so that on single phase-to-ground faults only the faulty phase wire is disconnected at each end of the line and then immediately reclosed. This allows synchronizing current to flow over the two sound-phase conductors during the time the faulted phase wire is out of service. With single-pole tripping slower speed reclosing, as compared to three-pole operation, can be utilized with a definite gain in the stability limit.¹