Revision of TRV requirements for the application of generator circuit-breakers

• A review of TRV parameters for generator circuit-breaker applications has been done.
• For system-source faults TRV td can exceed the standardised values.
• For generator-source faults TRV E2/V can exceed the standardised values.
• In case of out-of-phase conditions.∘E2/V and RRRV increase with out-of-phase angle.∘td Seems to be somewhat constant with the out-of-phase angle.

The requirements imposed on generator circuit-breakers greatly differ from the requirements imposed on other transmission and distribution circuit-breakers. Due to the location of installation between the generator and the associated step-up transformer, a generator circuit-breaker must meet high technical requirements with respect to rated normal currents, short-circuit currents, fault currents due to out-of-phase conditions and transient recovery voltages. The question whether the transient recovery voltage requirements laid down in IEEE Std C37.013-1997 (R2008) and in IEC/IEEE 62271-37-013 are adequate for the application of generator circuit-breakers in modern power stations is considered in the present work.In order to quantify the transient recovery voltage requirements for the application of generator circuit-breakers a comprehensive survey of different fault conditions occurring in several power stations has been performed. The fault transients’ simulations have been performed by means of the Electromagnetic Transients Program (EMTP).