Evaluating generator breakers short-circuit duty using IEEE Std. C37.010 and C37.013

This paper describes a procedure for calculating generator circuit breaker duty. Presently, commercially available software products help in determining the duty for a general purpose circuit breaker. However, further calculations are needed to determine the duty for a special purpose generator circuit breaker. IEEE Std C37.010-1999 (Application Guide for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis) provides the calculation procedure for general-purpose circuit breakers. This paper presents a procedure to evaluate a special purpose generator-circuit breaker, providing a duty multiplication factor based on the test X/R ratio of generator breakers given in IEEE Std C37.013 (Standard for AC High-Voltage Generator Circuit Breakers Rated on a Symmetrical Current Basis).