What this MCCB is and what it does
The Siemens 3VA2063-8HN42-0AA0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection — meaning it sits at the feeder or main breaker position in a distribution panel, not on a specific motor or load branch. It carries a continuous rated current of 63 A across the full 40 °C to 70 °C ambient range, so no derating is needed as the panel warms up. That's a solid spec for a main in a control cabinet that sees summer heat. The interrupting ratings tell you where this breaker can clear a fault without welding or rupturing: 440 kA at 240 V, 330 kA at 415 V and 440 V, 220 kA at 500 V, and 52.5 kA at 690 V. Those are high numbers — this is a current-limiting MCCB meant for high-fault installations like transformer secondaries or large busway feeds. The 4-pole construction handles three-phase plus neutral switching, which is standard for North American and some European distribution schemes.
ETU350 trip unit — what it controls
The overcurrent release is an ETU350, an electronic trip unit with adjustable long-time, short-time, instantaneous, and ground-fault protection curves. It's the mid-range electronic trip in the 3VA family — not the basic thermal-magnetic, not the full communications-enabled ETU600. You set the pickup and delay via rotary dials on the front face; no software or handheld programmer needed. The 63 A frame rating is the maximum continuous current this breaker can carry, so the trip unit's sensor is sized for that.
Physical fit and panel integration
The breaker measures 140 mm wide, 181 mm high, and 86 mm deep. That 140 mm width is the standard 4-pole MCCB footprint for the 3VA2 frame — it occupies four 35 mm DIN-rail modules worth of panel space, though the breaker itself bolts to a mounting plate, not a DIN rail. The IP40 front protection means it's sealed against tools and wires larger than 1 mm from the front, but the rear terminals are open to the cabinet. Plan for finger-duct clearance above and below for the line and load lugs.