400 A MCCB with 4800 A frame — what the ratings mean for your panel
The Siemens SENTRON 3VA2440-5HN32-0JA0 is a 3-pole molded case circuit breaker rated 400 A continuously at 40 °C, built on a 4800 A frame. That frame size means the internal mechanism and arc chambers are designed for fault currents up to 4800 A — the breaker's interrupting capacity is what changes with system voltage: 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 9 kA at 690 V. For a 400 A feeder on a 480 V or 400 V distribution board, the 121 kA SCCR at 415 V gives substantial headroom above typical available fault current, so selectivity with downstream breakers is practical without oversizing. Rated current holds flat at 400 A from 40 °C through 70 °C — no derating needed across typical switchroom ambient temperatures. The shunt trip release (STL) allows remote tripping via a control signal, which is useful for emergency-stop circuits or interlocking with a fire-alarm panel. Designed for line protection, so it's suited for feeder circuits rather than motor or generator protection.
Physical fit and panel integration
Dimensions are 248 mm high, 138 mm wide, 110 mm deep — a standard MCCB footprint that fits most 600 V switchboard cubicles and panel-mounted enclosures. The 110 mm depth leaves clearance for rear-connected busbars or cable lugs in a typical 400 mm deep enclosure. Three-pole design with no undervoltage release and no auxiliary switch fitted as standard; the shunt trip occupies the auxiliary release slot.
Power loss and thermal management
Maximum power loss is 63.5 W at rated current. In a sealed enclosure with multiple breakers, that heat must be accounted for in the thermal design — a single unit in open air is fine, but a dense panel may need forced ventilation or derating above 70 °C ambient.