400 A MCCB with ETU350 — what the ratings mean for the panel
The SENTRON 3VA2340-5HN42-0AA0 is a 4-pole molded case circuit breaker rated for 400 A continuous current at 40 °C, designed for line protection in distribution panels. The ETU350 electronic trip unit provides adjustable overload and short-circuit protection curves, letting you coordinate selectivity downstream without swapping trip units. At 240 V it interrupts 187 kA; at 415 V that drops to 121 kA, and at 690 V to 7.5 kA — so the interrupting capacity is heavily phase-to-phase voltage dependent, and the 690 V figure governs any 690 V line-to-line application. The insulation voltage is rated 800 V, which covers 690 V systems with margin.
Thermal derating — the real current you can carry
The 400 A rating holds up to 50 °C ambient. Above that, the breaker must be derated: 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 inside a non-air-conditioned enclosure or near other heat sources — the continuous current must be reduced accordingly. The maximum power loss is 96 W, which contributes to the enclosure thermal load and should be factored into the cabinet cooling calculation.
Physical fit and mounting
Dimensions are 110 mm deep, 184 mm wide, and 248 mm tall. The 4-pole format occupies the same footprint as other 3VA frame-size breakers, so it drops into existing panel cutouts and busbar arrangements designed for the 3VA platform. Front IP40 protection means it is suited for enclosed distribution boards where the front face is behind a door or cover — not for open-panel washdown environments.
Compliance and approvals
The SENTRON 3VA series carries IEC/EN 60947-2 certification for molded case circuit breakers. The ETU350 trip unit is a standard electronic release with no communication function, no ground-fault monitoring, and no undervoltage release integrated — those are handled by separate accessories. The breaker has no trip indicator and no voltage trigger. It is designed for line protection, not motor protection (no thermal overload curve for motor starting).