What this 400 A MCCB delivers
The Siemens SENTRON 3VA2440-7HL32-0HL0 is a 3-pole molded case circuit breaker rated for 400 A continuous current at 40 °C, with a breaking capacity of 330 kA at 240 V AC. That 330 kA SCCR at 240 V means it safely interrupts very high fault currents without cascading upstream — critical for main feeders in large distribution boards or transformer secondaries. The ETU320 electronic trip unit provides adjustable overload and short-circuit protection curves, so you can coordinate selectivity with downstream breakers. This is a line protection version — no ground-fault module, no communication function, no phase-failure detection. It's built for straightforward overcurrent protection in a main or branch feeder. The shunt trip release (STL) allows remote tripping via a control signal, which is useful for emergency-stop circuits or supervisory shutdown.
Breaking capacity across voltages
Breaking capacity drops as voltage rises: 330 kA at 240 V, 242 kA at 415 V and 440 V, 187 kA at 500 V, and 52.5 kA at 690 V. At 690 V the 52.5 kA figure still covers most industrial service-entrance faults, but verify your available fault current at the point of installation. The rated insulation voltage is 800 V, so the breaker is rated for use on 690 V systems.
Thermal derating and ambient limits
The breaker holds 400 A from 40 °C up to 50 °C without derating. Above that, current must be reduced: 384 A at 55 °C, 376 A at 60 °C, 368 A at 65 °C, and 360 A at 70 °C. Operating ambient range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. The maximum power loss at rated current is 63.5 W per pole — something to account for in enclosed panel thermal calculations.
Auxiliary and trip accessories
Factory-fitted with 2 auxiliary switches, 1 trip alarm switch, and 1 electrical alarm switch (HQ configuration). The integrated auxiliary trip is a shunt trip (STL) — part number 3VA9688-0BL30. The basic switch assembly is 3VA2440-7HL32-0AA0. No undervoltage release is fitted. The mechanical endurance is rated at 15,000 operations — sufficient for infrequent switching in a distribution role, not for motor-starting duty.
Panel fit and dimensions
Dimensions: 248 mm high, 138 mm wide, 110 mm deep. The 138 mm width is standard for a 3-pole 400 A frame in the 3VA platform. Mounts on a backplate or DIN rail via the appropriate adapter (not included). The depth of 110 mm means it fits most standard distribution enclosures without protruding into the wiring gutter.