What it is and what it does
The Siemens SENTRON 3VA2340-6HN32-0AB0 is a 3-pole molded case circuit breaker (MCCB) rated for 400 A continuous current at 40 °C, designed for line protection in distribution panels. It carries a 242 kA interrupting rating at 240 VAC and still delivers 187 kA at 415 V and 440 V, dropping to 121 kA at 500 V and 7.5 kA at 690 V — so it handles high-fault-current service entrances and main feeders without cascading upstream. The unit ships with two auxiliary switches (HP design) factory-installed and no auxiliary release or undervoltage release. It has no trip indicator, no voltage trigger, no communication function, and no ground-fault monitoring — this is a straight thermal-magnetic or electronic-trip line-protection breaker, not a multifunction power-management device.
Thermal derating and panel integration
The breaker holds its full 400 A rating from 40 °C through 50 °C ambient. Above that it derates: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. If the panel ambient runs hot — say next to a transformer or in a non-climate-controlled enclosure — size the feeder for the derated value, not the nameplate 400 A. Physical footprint is 248 mm tall, 138 mm wide, 110 mm deep — a standard 3-pole MCCB form factor for DIN-rail or panel-mount backplate. Maximum power loss is 96 W, so account for that heat in the enclosure ventilation calculation.