When sourcing MCCBs, you must prioritize the Rated Current (In), which typically ranges from 15A to 2500A, and the Rated Short-Circuit Breaking Capacity (Icu). Ensure the Icu meets or exceeds the calculated fault current of your electrical system. Additionally, verify the Rated Insulation Voltage (Ui) and Rated Impulse Withstand Voltage (Uimp) to ensure the device can handle transient overvoltages. For industrial automation, look for MCCBs with electronic trip units that offer adjustable settings for Long-time (L), Short-time (S), Instantaneous (I), and Ground-fault (G) protection.