What this 3VA2 breaker delivers
The Siemens 3VA2340-5JQ42-0AK0 is a 4-pole molded case circuit breaker in the 3VA2 IEC frame 400 platform, rated In=400A with an interrupting capacity Icu=55kA at 415V AC — breaking capacity class M. That 55kA figure means it can safely clear a bolted fault up to that level without welding contacts or rupturing the arc chamber, which is the difference between a contained trip and a cascading failure upstream. The ETU560 electronic trip unit gives you LSIG protection: long-time (L) overload, short-time (S) short-circuit with adjustable delay, instantaneous (I), and ground-fault (G) that can be switched off. Overload protection Ir is adjustable from 160A to 400A, so you dial in the cable or bus rating, not the other way around.
Trip unit and protection settings
Short-circuit protection Isd adjusts 0.6 to 10x In, and the instantaneous pickup Ii covers 1.5 to 10x In — wide enough to ride through motor inrush on a 400A feeder while still catching a hard fault. The ground-fault pickup Ig ranges 0.2 to 1x In with a time delay tg of 0.05 to 0.8 seconds, and you can switch it off entirely if the downstream scheme already handles GF. Neutral conductor protection is adjustable from OFF up to 100% of In. This breaker ships with a nut keeper kit, one auxiliary switch (changeover H), and one trip alarm switch (changeover) — wired-in status and alarm feedback without opening the cover.
Where it fits in the panel
The 3VA2 frame 400 is a fixed-mount, 4-pole breaker sized for IEC distribution panels and motor control centers. It occupies a standard draw-out cradle or bolted connection — no DIN-rail snap-on here. The ETU560 is powered by integral current transformers, so no control power is needed for the trip unit itself. The auxiliary and alarm switches give the PLC or BMS a dry-contact status without an extra interface relay.