ABSTRACT
The strategy for single-pole tripping is to isolate only the faulted phase at the occurrence of a transmission line single-line-to-ground fault, and to isolate some phases for all other faults. The influence of voltage variation throughout the power system is reduced as a consequence of single-pole tripping. This chapter describes the advantages of single-pole tripping includes: stability considerations, phase selection methods to assure proper faulted-phase identification, the difficulty of subsequent fault identification and the symmetrical component representation of a system following single-pole tripping. The advantages also includes the influence on rotating machinery of the transmission line single-phasing, following single-pole tripping and the near-certainty of increased use of single-pole tripping as a result of decreasing availability of rights-of-way. The relaying and circuit breakers are available for single-pole tripping, allowing, with minor cost addition, the possibility, in some cases, of substantial improvements in power system stability.
