What this 630 A MCCB means on the line
The 187 kA breaking capacity at 240 V (121 kA at 415 V, 121 kA at 440 V, 75.6 kA at 500 V, and 17 kA at 690 V) means it can safely interrupt a fault up to those levels without the arc blowing upstream. That kind of interrupting rating is what you need when the transformer is big and the bolted-fault current is serious.
Current derating and thermal reality
The 630 A rating at 40 °C drops as the ambient climbs: 612 A at 45 °C, 593 A at 50 °C, 575 A at 55 °C, 557 A at 60 °C, 538 A at 65 °C, and 520 A at 70 °C. The maximum power loss is 164.5 W, so plan for the heat dissipation in the enclosure.
Physical fit and integration notes
The breaker measures 248 mm high by 138 mm wide by 110 mm deep. If you need remote status or trip indication, you'll add the auxiliary contact separately.