"Interrupting Current is the current in a pole of a switching device at the instant of the initiation of the arc." (ANSI standard C37.03)
As explained in the section on low-voltage protective equipment, the short circuit current consists of the symmetrical AC component and the DC component. The resulting asymmetrical current and the operating speed of the device determine the interrupting duty which a circuit breaker or fuse is subjected to in clearing a short circuit.
