Siemens SENTRON 3VA2340-5HN42-0AB0 — 400 A MCCB with ETU350 Trip Unit
The Siemens 3VA2340-5HN42-0AB0 is a SENTRON molded case circuit breaker (MCCB) rated for 400 A continuous current at 40 °C through 50 °C, with a 4-pole configuration and an ETU350 electronic overcurrent release. It is designated for line protection and carries a rated insulation voltage of 800 V. The interrupting ratings are substantial: 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 17 kA at 690 V. This is a current-production part, sourced to order against an RFQ.
Interrupting Capacity and SCCR Planning
The 187 kA at 240 V and 121 kA at 415 V mean this breaker can safely clear extremely high fault currents typical of large transformer secondaries or high-capacity busways. For a site electrical engineer doing a selective coordination study, those numbers give headroom to avoid nuisance upstream tripping. At 690 V the rating drops to 17 kA — still adequate for most 690 V motor control centers, but verify the available fault current at the point of installation.
Thermal Derating and Panel Fit
The breaker carries 400 A continuously up to 50 °C ambient, then derates to 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. In a sealed panel with limited airflow, that derating curve is the real selection parameter — not the 400 A nameplate. The enclosure dimensions (248 mm height, 184 mm width, 110 mm depth) fit standard SENTRON 3VA mounting footprints; check the panel cutout against the existing 3VA backplate or DIN-rail adapter.
Trip Unit and Auxiliary Contacts
The ETU350 electronic trip unit provides adjustable long-time, short-time, instantaneous, and ground-fault protection curves. It ships without undervoltage release, voltage trigger, phase failure detection, or communication function — this is a straightforward line-protection breaker, not a smart breaker. Two auxiliary switches (HP type) are integrated for status feedback to the PLC or SCADA system. The basic switch variant is 3VA2340-5HN42-0AA0.
Environmental and Storage Limits
Operating temperature range is -25 °C to 70 °C; storage range extends from -40 °C to 80 °C. The storage limits govern handling and warehousing, not running conditions. Maximum power loss is 96 W — account for that in the enclosure thermal budget. Front protection is IP40, meaning tools and fingers are blocked, but the breaker is not sealed against water ingress; install in a suitable cabinet for washdown or outdoor environments.