What this 400 A SENTRON MCCB delivers on the line
The Siemens 3VA2340-5HN42-0JL0 is a 4-pole SENTRON molded case circuit breaker rated for 400 A continuous current at 40 °C, with an ETU350 electronic trip unit. It holds the same 400 A rating through 50 °C, then derates to 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C — so in a warm panel you lose about 15 % of headroom at the top end. Interrupting capacity runs 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; that 187 kA at 240 V means it handles the full available fault current on a high-capacity 240 V distribution bus without cascading upstream breakers. This is a line-protection variant — no ground-fault monitoring, no phase-failure detection, no communication module. The auxiliary contact block ships with 2 auxiliary switches, 1 trip alarm switch, and 1 electrical alarm switch (HQ version). A shunt trip (STL) is integrated; there is no undervoltage release. The ETU350 release gives adjustable long-time, short-time, instantaneous, and ground-fault protection curves, so you can coordinate selectivity downstream without swapping the breaker.
Panel fit and integration
The 3VA2340-5HN42-0JL0 measures 248 mm high by 184 mm wide by 110 mm deep — a standard SENTRON 3VA2 frame size. It mounts on a DIN rail or can be screw-fixed to a backplate. The 184 mm width for a 4-pole breaker means you need at least 9 module-widths of DIN rail (at 18 mm per module) plus breathing space on each side for cable bending radius. Maximum power loss is 96 W, so factor that into your enclosure thermal budget — a sealed stainless box will need forced ventilation or derating at the top of the ambient range. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. The 15 000 mechanical endurance cycles are typical for a 400 A frame — fine for distribution duty but not for frequent switching under load. The basic switch module is order code 3VA2340-5HN42-0AA0; the integrated auxiliary trip is 3VA9688-0BL32. If you need to swap the trip unit or add auxiliary contacts later, those are the service parts to order.