It breaks 121 kA at 240 V and 75.6 kA at 415 V, so it handles high available fault current on a 480Y/277 V or 208Y/120 V secondary without cascading upstream. Three poles, line protection version, no undervoltage release, no communication module — this is a straight thermal-magnetic breaker for a distribution panel.
Thermal curve and panel fit
The 63 A rating holds flat across 40 °C to 50 °C; above that it derates to 60.48 A at 55 °C and 56.7 A at 70 °C. In a sealed panel hitting 60 °C ambient, you lose about 4 A of headroom. The 70 mm depth and 76.2 mm width fit the standard SENTRON 3VA footprint — same cutout as the 3VA1110 frame.