MCCB for high-fault panel mains
The Siemens SENTRON 3VA2340-5HN32-0CC0 is a 3-pole molded case circuit breaker rated for 400 A continuous current at 40 °C, with a breaking capacity of 187 kA at 240 V and 121 kA at 415 V — figures that cover most industrial service-entrance and feeder applications without needing a current-limiting upstream device. It is configured as a line-protection device (no ground-fault monitoring, no phase-failure detection) with an ETU350 electronic trip unit and an integrated undervoltage release (UVR). The auxiliary contact block carries two HQ-form auxiliary switches. The 110 mm depth and 138 mm width fit the standard SENTRON 3VA mounting footprint — it drops into the same panel cutout as other 3VA frame sizes, so a panel originally specified for a lower-rated 3VA can be upgraded to this 400 A unit without re-drilling the gland plate.
Thermal derating and real-world current
The 400 A rating holds flat from 40 °C to 50 °C. Above that, it derates linearly: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. If your enclosure ambient runs at 60 °C, the usable current is 370 A — not the nameplate 400 A. Plan the load accordingly. Maximum power loss at rated current is 98.5 W. That heat stays inside the enclosure; factor it into your thermal budget, especially in a sealed, non-ventilated panel.
Integration and wiring notes
The 3VA2340-5HN32-0CC0 mounts on a standard DIN rail or can be screw-fixed to a backplate. The 248 mm height leaves clearance for busbar connections above and below. The auxiliary switch block (2 HQ contacts) is factory-integrated — no field assembly required. The undervoltage release is built in; it trips the breaker when coil voltage drops below the dropout threshold. If your control circuit uses a separate UVR module, note that this unit already carries one — you do not need to order it separately.