Effect of previously install circuit breaker due to the upcoming new generating station

This paper presents the effect in the breaking capacity of previously installed circuit breaker due to the upcoming of new generating stations in the near vicinity. The MVA capacity of the circuit breaker needs to be upgraded owing to increase in the symmetrical fault current level. The circuit breaker connected to the older generating station can maloperate. The circuit breaker parameters have been calculated and tabulated connected to the smaller generating unit at both ends of the transmission line with respect to a symmetrical fault. The more the difference in the rating of the two generating unit the higher is the MVA rating required for circuit breaker upgradation.