The Siemens SENTRON 3VA2163-6HL36-0DH0 is a 3-pole molded case circuit breaker (MCCB) rated for 63 A continuous current across the full ambient range from -25 °C to 70 °C — no derating needed up to that ceiling. It is designed for line protection in distribution panels and switchgear assemblies, with a breaking capacity that starts at 242 kA at 240 V and holds at 187 kA through 415–440 V, then drops to 121 kA at 500 V and 3.7 kA at 690 V. That 242 kA at 240 V figure is the headline: it handles very high available fault currents typical at the secondary of a large step-down transformer, so this breaker belongs upstream in a feeder, not downstream on a branch circuit.
The breaker mounts to a mounting plate or DIN rail via the SENTRON 3VA base adapter; wire lug clearance on a 63 A frame is standard for 50 mm² Cu cable.