What this MCCB carries in the carton
The Siemens SENTRON 3VA2340-5HN42-0AF0 is a 4-pole molded case circuit breaker rated for 400 A continuous current at 40 °C, with an interrupting capacity of 187 kA at 240 V and 121 kA at 415 V. It ships with the ETU350 electronic overcurrent release and includes one auxiliary switch plus one trip alarm switch (HQ version) — so the kit is complete for line protection duty without needing a separate aux contact order. The basic switch supplied is 3VA2340-5HN42-0AA0, and the integrated auxiliary trip is 3VA9608-0BB11. No holes in the box for the core protection function.
Interrupting ratings — what they mean for panel protection
The 187 kA at 240 V and 121 kA at 415 V are the maximum fault currents this MCCB can safely interrupt without damage to itself or upstream gear. At 500 V the rating drops to 75.6 kA, and at 690 V to 17 kA — the interrupting curve follows system voltage. For a 400 A feeder on a 415 V supply with a high fault-current transformer, this breaker handles the full available fault without cascading to a main breaker. The 800 V rated insulation voltage (Ui) confirms it's rated for 690 V line-to-line systems.
Thermal derating — the real continuous current at panel ambient
Rated 400 A continuous from 40 °C through 50 °C. At 55 °C it derates to 385 A, at 60 °C to 370 A, at 65 °C to 355 A, and at 70 °C to 340 A. For a panel running at 55 °C ambient — common in sealed enclosures with solar load — the breaker still carries 385 A, not the full 400 A. The maximum power loss is 96 W, which factors into enclosure thermal calculations. Operating range is -25 °C to 70 °C; storage range -40 °C to 80 °C.
Mounting dimensions and panel fit
Dimensions: 248 mm high, 184 mm wide, 110 mm deep. The 184 mm width is the 4-pole frame — standard for a 400 A MCCB in this class. Mounts on a DIN rail or direct panel-mount via the screw terminals. The 110 mm depth includes the arc chamber and line/load lugs; verify gland plate clearance if the panel has a rear-mounted busbar system. Latching endurance is rated at 15 000 operations.
What this breaker does not include
No undervoltage release, no shunt trip (voltage trigger), no communication module, no phase failure detection, no ground fault monitoring, and no other measurement function. The ETU350 release handles overcurrent protection only — line protection version. If the application requires remote tripping or ground fault, this is not the variant. The auxiliary contact set (1 NO/NC + 1 trip alarm) is present and wired to the HQ terminals.