Chapter 8
Case Studies Related to Breaker Failure Protection System Disturbances
In this chapter we cover a variety of breaker failure case studies. Case Study 8.1 documents the undesired operation of a breaker failure due to an initiation relay welded contact which was determined by playing back the DFR record using the COMTRADE format to test the relay and confirm its operation. Case Study 8.2 emphasizes the importance of generator phase backup devices as well as remote backup protection for substations to clear faults during extreme contingencies that can occur as a result of simultaneous breaker failures. Case Study 8.3 displays magnetic flux cancellation phenomenon associated with a circuit breaker dual trip coil assembly as the main cause of substation isolation from the bulk power system. Case Study 8.4 describes an incident involving numerous breakers tripping as well as generation rejection initiation by a fault that grew out of proportion due to the undesired operation of a breaker failure relaying system, by backfeeding to the fault detector CT circuit, thus causing additional breaker tripping. Case Study 8.5 describes a unit breaker mechanical problem during an attempt to synchronize a unit to the system while in a pumping mode, resulting in an out-of-step condition, with the unit oscillating three times against the system.
Case Study 8.6 covers re-striking phenomena of oil circuit breakers while clearing simultaneous B-g faults on two 230-kV parallel circuits. Case ...