MCCB for line protection — 400 A, 3-pole, with shunt trip
The Siemens 3VA2340-7HN32-0KH0 is a SENTRON molded case circuit breaker (MCCB) rated for 400 A continuous current at ambient temperatures up to 50 °C, after which it derates linearly to 340 A at 70 °C. It is a 3-pole device designed for line protection — meaning it sits at the incoming feeder or main distribution point, not downstream branch circuits. The interrupting ratings are substantial: 330 kA at 240 V, 242 kA at 415/440 V, 187 kA at 500 V, and 7.5 kA at 690 V. That 330 kA figure at 240 V tells you this breaker handles high-fault scenarios typical of large transformer secondaries or industrial service entrances — it's not a general-purpose branch breaker. This variant includes a shunt trip release (STL) for remote tripping, plus two auxiliary switches and one trip alarm switch. No undervoltage release, no ground-fault monitoring, no communication module — it's a straightforward line-protection breaker with remote-trip capability. The power loss is 96 W maximum, which matters for enclosure thermal management when the breaker is fully loaded.
Panel fit — dimensions and mounting
Dimensions: 248 mm high, 138 mm wide, 110 mm deep. That 110 mm depth is the body only — account for wiring space, shunt-trip leads, and auxiliary switch cabling when sizing the enclosure. The breaker mounts on a standard DIN rail or directly to a backplate; the 138 mm width for a 3-pole 400 A MCCB is compact for its rating class.