Short-circuit ratings of power circuit breakers

THE SHORT-CIRCUIT RATINGS of power circuit breakers define the maximum short-circuit currents which the circuit breakers can be required to close, carry, and interrupt. These currents are transient and contain both direct and alternating components. They vary in magnitude between the time a fault occurs and the time the circuit breaker interrupts. Consequently, several ratings are used to define the maximum short-circuit current to which the circuit breaker may be subjected.