The Siemens 3VA2163-5HL36-0CC0 is a SENTRON 3-pole molded case circuit breaker rated for 63 A continuous current across the full ambient range from 40 °C to 70 °C — no derating needed up to that ceiling. Its interrupting capacity hits 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 3.7 kA at 690 V — so it handles high-fault utility feeds and transformer secondaries without cascading upstream.
The 86 mm depth matters when the breaker sits behind a gland plate or in a shallow enclosure; it leaves room for cable bending radius and auxiliary wiring without forcing a deeper can.