When a breaker and a MC (Magnetic Contactor) or an MMS and a MC are combined and used, the breaker

breaks "opens" to protect line if there is any fault but part of short circuit current will be transmitted to

lower contactor and overload relay too. So lower contactor and overload relay should be

structured to resist certain amount of short circuit current.

KSC and IEC standards are regulating about this with Type II coordination. 

According to this, LS Industrial Systems also completed the test as KSC

and IEC standards.  IEC selecting table.