Relay protection out-of-step tripping
Controlled system separation is achieved with an out-of-step tripping (OST) protection system at preselected network locations. It is the purpose of this paper to describe the relays and schemes available to provide these functions and discuss their application on present-day power systems. These characteristics may be circular, mho characteristics, quadrilateral, characteristics, or other sh erating power, Pa, will be essentia ly zero. An unstable power swing results in a generator or group of generators experiencing pole slipping or loss-of-synchronism for which some corrective action must be taken.
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