The Siemens SENTRON 3VA2163-7HN32-0BC0 is a 3-pole molded case circuit breaker rated for 63 A continuous current across the full 40 °C to 70 °C ambient range — no derating needed as the panel warms up. Its interrupting capacity hits 330 kA at 240 V, 242 kA at 415 V, and still holds 187 kA at 500 V, which means it can sit upstream of a high-fault bus without cascading to the main breaker.
Built-in release and auxiliary switch complement
Power loss and thermal budget
Maximum power loss is 6.5 W. In a sealed enclosure with multiple breakers, that 6.5 W per unit adds to the internal heat rise — account for it in your thermal calculation, especially if the panel is already near the 70 °C operating limit.