What this 400 A MCCB carries
The Siemens SENTRON 3VA2440-8HL32-0AA0 is a 3-pole molded case circuit breaker rated for a continuous current Iu of 400 A across the full operating temperature range from 40 °C to 70 °C — no derating needed up to that ceiling. It's built for line protection duty, meaning it sits at the main feeder or large subfeed, not on a motor branch where you'd want a specific motor-protective curve. Breaking capacity is the headline: 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. That's a serious interrupting rating — it can clear a massive fault without venting or cascading upstream, which matters when you're coordinating a high-available-fault-current industrial service.
ETU320 trip unit — what it controls
The overcurrent release is an ETU320, an electronic trip unit. That gives you adjustable long-time, short-time, instantaneous, and ground-fault protection curves (though this specific variant ships without ground-fault monitoring). The electronic trip means better selectivity coordination downstream compared to a thermal-magnetic — you can set the I²t curves to ride through inrush without nuisance tripping. Rated insulation voltage is 800 V, so it's comfortable on 480/277 V and 600 V systems with margin. The front face carries an IP40 rating — fine for a clean indoor panel, but if this breaker lives near a washdown zone or outdoors, you'll want an enclosure over it.
Panel fit and thermal budget
Dimensions are 248 mm high, 138 mm wide, 110 mm deep. That's a standard 3-pole MCCB footprint for this current class — it'll bolt into a SENTRON panelboard or a standalone enclosure without surprises. Maximum power loss is 63.5 W; that's the heat you need to vent from the enclosure, so factor it into your thermal calculation if you're packing multiple breakers in a small cabinet.