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. A shunt trip (STL) is integrated; there is no undervoltage release.
The 3VA2340-5HN42-0JL0 measures 248 mm high by 184 mm wide by 110 mm deep — a standard SENTRON 3VA2 frame size. 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. 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.