4-pole 40 A MCCB with ETU350 — what the ratings mean for a panel build
The Siemens 3VA2140-8HN42-0AA0 is a SENTRON 3VA2 molded case circuit breaker in a 4-pole configuration, rated for line protection duty. Its 40 A continuous current rating holds flat from 40 °C through 70 °C — no derating curve to calculate in a warm enclosure. The ETU350 electronic trip unit gives adjustable overload and short-circuit protection curves, a step up from fixed thermal-magnetic breakers for coordinating with downstream selective schemes. Interrupting capacity is the headline here: 440 kA at 240 V, 330 kA at 415 V and 440 V, 220 kA at 500 V, and 52.5 kA at 690 V. That puts this breaker in the high-fault tier — suitable for main or feeder positions where available fault current exceeds what a standard MCCB can clear. The 800 V rated insulation voltage (Ui) confirms it's built for 690 V systems with margin. Dimensions are 181 mm high, 140 mm wide, 86 mm deep — a compact 4-pole footprint that fits standard SENTRON panel cutouts. IP40 on the front means it's protected against tools and wires >1 mm, but not washdown; keep it inside a sealed enclosure for wet environments.
Integration notes — panel fit and wiring
The 86 mm depth matters when you're laying out a shallow backpanel or a gland-plate clearance. At 140 mm wide, it occupies three standard 45 mm module positions on a DIN rail — verify your rail length if you're swapping into an existing assembly. The 4-pole format means it switches all three phases plus neutral; the N-conductor protection can be set to OFF (no neutral protection) or 100% (full neutral protection) via the ETU350 settings. Power loss is 1.2 W maximum — negligible for thermal budgeting in a crowded enclosure. Operating temperature range is -25 °C to 70 °C; storage from -40 °C to 80 °C. The 40 A rating is continuous at any temperature in that operating range, so no summer derating worry.