Momentary Current is the RMS current applicable to the first cycle of short circuit current (ANSI standard C37.03). Most manufacturers give breakers a momentary rating 1.6 times the maximum current which the breaker can interrupt. A breaker selected on the basis of interrupting duty will normally have an adequate momentary rating. However, check the momentary duty rating.
The short circuit ratings of power fuses are published as the interrupting capability in symmetrical amperes. Their asymmetrical capability is 1.6 times the symmetrical ampere rating.
