What this 400 A MCCB is and what it does
The Siemens SENTRON 3VA2340-5HN32-0KC0 is a 3-pole molded case circuit breaker (MCCB) rated for 400 A continuous current, designed for line protection in distribution panels and switchgear. It carries a 187 kA interrupting rating at 240 V AC, stepping down to 121 kA at 415 V and 7.5 kA at 690 V — the high short-circuit capacity at lower voltages makes it a fit for main or feeder breakers in high-fault installations like industrial substations or large motor control centers. The breaker ships with a factory-fitted shunt trip release (STL) and two HQ auxiliary switches, so it arrives ready for remote tripping and status feedback without additional wiring modifications. The base switch is the 3VA2340-5HN32-0AA0, meaning the -0KC0 variant adds the shunt trip and auxiliary contacts as a pre-configured option.
Thermal derating and real-world current capacity
The 400 A rating holds at ambient temperatures up to 50 °C without derating. Above that, the continuous current must be reduced: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. If the breaker lives in a hot panel — say, next to transformers or drives — the 55 °C and 60 °C figures are the ones that govern the load it can actually carry. Maximum power loss is 96 W at rated current, which contributes to the enclosure's thermal budget. Operating range is -25 °C to 70 °C; storage range is -40 °C to 80 °C.
Panel fit and integration notes
Dimensions are 248 mm high, 138 mm wide, and 110 mm deep — a standard 3-pole MCCB footprint that fits most DIN-rail or panel-mount enclosures. The 110 mm depth is the dimension to check against gland-plate clearance or shallow backboxes. No communication function is built in; this is a standalone breaker without Modbus or PROFIBUS.