Short-Circuit Current Rating per IEC 61643 and UL1449

In IEC61643, Isc means maximum prospective short-circuit current from the power system for which the SPD, in conjunction with the disconnector specified, is rated.
While in UL 1449, Isccr, the suitability of an SPD for use on an AC power circuit that is capable of delivering not more than a declared rms symmetrical current at a declared voltage during a short circuit condition.
SCCR is not the same as AIC (Amp Interrupting Capacity).SCCR is the amount of“available” current that the SPD can be subjected to and safely disconnect from the power source under short circuit conditions. The amount of current “interrupted by the SPD is typically significantly less than the“available”current.