What this MCCB is and what it does
The Siemens 3VA2340-6KP32-0KH0 is a SENTRON molded case circuit breaker (MCCB) configured for line protection — meaning it guards distribution feeders and main panelboards against overloads and short circuits, not motor or generator circuits. It carries a rated continuous current Iu of 400 A (at 40 °C) and uses an ETU850 electronic trip unit, which gives you adjustable long-time, short-time, instantaneous, and ground-fault protection curves. The 3-pole frame is rated for an insulation voltage Ui of 800 V and delivers breaking capacities from 242 kA at 240 V down to 40 kA at 690 V.
Thermal derating — where the 400 A holds and where it drops
This MCCB holds its full 400 A rating from 40 °C through 50 °C ambient. At 55 °C it derates to 375 A, at 60 °C to 350 A, at 65 °C to 325 A, and at 70 °C to 300 A. If your panel runs hot — say a packed enclosure near a furnace line or a transformer vault — that derating curve determines whether this frame size works or you need to step up. The maximum operating temperature is 70 °C; storage range is -40 °C to 80 °C.
Breaking capacity across voltages — selectivity planning
The interrupting ratings span the common industrial voltage bands: 242 kA at 240 V, 187 kA at 415 V and 440 V, 121 kA at 500 V, and 40 kA at 690 V. For a 480 V distribution panel (common in North America) the relevant figure is the 440 V rating at 187 kA — that is well above typical available fault current for most secondary substations, so you have headroom for selective coordination downstream. At 690 V, the 40 kA rating still covers most industrial motor-control-center faults.
Dimensions and panel fit
The MCCB measures 248 mm high, 138 mm wide, and 110 mm deep — a 3-pole frame that fits standard Siemens 3VA switchboard and panelboard mounting patterns. The 110 mm depth is shallow enough for most 600 mm deep enclosures without interfering with the gland plate or door swing. Power loss is 96 W maximum, so account for that heat in the enclosure thermal calculation.
Integrated auxiliary and trip options
This variant ships with 2 auxiliary switches plus 1 trip alarm switch (HQ configuration), a shunt trip release (STL), and a voltage trigger. The supplied basic switch is order code 3VA2340-6KP32-0AA0; the integrated auxiliary trip is 3VA9688-0BL33. Communication function and other measurement functions are present — the ETU850 supports Modbus RTU communication for power monitoring and trip data. There is no undervoltage release or phase-failure detection on this specific configuration.