63 A MCCB with ETU350 — panel fit and interrupting performance
The Siemens SENTRON 3VA2063-5HN32-0KH0 is a 3-pole molded case circuit breaker rated 63 A continuous current (Iu) at 40 °C, configured for line protection with an ETU350 electronic trip unit. The interrupting ratings span 187 kA at 240 V down to 3.4 kA at 690 V, so the 240 V figure governs most North American panelboard applications while the 690 V number matters for European 400/690 V distribution.
Rated continuous current holds at 63 A from 40 °C through 50 °C, then steps down: 60.6375 A at 55 °C, 58.275 A at 60 °C, 55.9125 A at 65 °C, and 53.55 A at 70 °C. That means the breaker carries its full 63 A rating in typical 40 °C panel ambient; above 50 °C you derate about 5 % per 5 °C increment. Maximum power loss is 5.4 W — negligible for thermal coordination in a crowded enclosure.