Experience With Single-Pole Relaying and Reclosing on a Large 132-Kv System

Three full years of operating experience with single-pole switching on five 132-kv transmission lines totaling 331 miles in length is presented and analyzed. Total number of faults for the period studied was 59, of which 54 were of temporary nature. Of these 54 temporary faults, 42 involved only one phase and ground, and 38 successful single-pole fault clearing operations were experienced. Conclusions are that singlepole switching has numerous advantages over multipole high-speed switching in that better system stability is realized by its use, longer phase de-energization time permits greater time for dissipation of ionized gases at the point of fault, and over-all system disturbance is minimized during fault clearing operation.