What this MCCB delivers for the line
The Siemens SENTRON 3VA2440-6HL32-0HC0 is a 3-pole molded case circuit breaker rated for 400 A continuous current at 40 °C, carrying the ETU320 electronic trip unit for line protection. It handles fault currents up to 242 kA at 240 V and 187 kA at 415 V, which means it can sit upstream of a distribution panel with high available fault current without needing a current-limiting fuse ahead of it. The 800 V rated insulation voltage (Ui) gives headroom for 480 V or 600 V class systems. The shunt trip (STL) and two HQ auxiliary switches are factory-integrated — no field assembly of add-on blocks.
Thermal derating and real-world current
The breaker holds its full 400 A rating up to 50 °C ambient. Above that, it derates to 384 A at 55 °C, 376 A at 60 °C, 368 A at 65 °C, and 360 A at 70 °C. If the panel ambient runs hot — say, near a drive cabinet or transformer — the 55 °C figure is the one to size against. The maximum power loss of 63.5 W matters for enclosure thermal calculations; that heat has to leave the cabinet.
Physical fit and panel integration
The breaker measures 248 mm high, 138 mm wide, and 110 mm deep. It mounts on a DIN rail or directly to a backplate via the SENTRON 3VA mounting accessories. The 3-pole footprint is standard for this frame size; verify the 138 mm width against the existing panel cutout or busbar spacing before committing the panel layout.
Trip unit and auxiliary configuration
The ETU320 electronic trip unit provides LI (long-time and instantaneous) protection for line/cable and distribution duty. It is not a ground-fault or phase-failure detection device — those functions are absent. The shunt trip (STL) allows remote tripping via a control signal; the two HQ auxiliary switches report the breaker position back to a PLC or status lamp. The basic switch assembly is order code 3VA2440-6HL32-0AA0, and the integrated auxiliary trip is 3VA9688-0BL30 — useful for spares planning.