What it is and what it does
The Siemens SENTRON 3VA2040-8KP36-0AA0 is a 3-pole molded case circuit breaker (MCCB) rated for 40 A continuous current, designed for line protection in industrial distribution panels. It carries an ETU850 electronic trip unit, which gives you adjustable overload and short-circuit protection curves — not a fixed thermal-magnetic response. The 800 V rated insulation voltage means it can sit on 690 V systems with margin, and the 440 kA breaking capacity at 240 V tells you this breaker can interrupt very high fault currents at lower voltages without self-destructing. The ETU850 release is the key differentiator here: it's a communicating electronic trip unit, so this breaker can report status and trip events over a network — useful for a plant floor where you want remote monitoring of breaker state without walking every panel. The line protection design means the trip curves are shaped for feeder and main breaker duty, not motor starting.
Breaking capacity across voltage — what the numbers mean
Breaking capacity drops as voltage rises: 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's typical for an MCCB — the arc extinguishes harder at higher voltages. For a 400 V distribution board (common in European industrial plants), the 330 kA figure gives substantial headroom above typical 50–65 kA available fault currents. At 690 V, the 52.5 kA still covers most heavy industrial installations. The 40 A continuous rating holds flat across the full ambient range from 40 °C to 70 °C (–), meaning no derating in a hot enclosure.
Panel integration
The breaker measures 105 mm wide, 181 mm high, and 86 mm deep — a standard 3-pole MCCB footprint for DIN-rail or panel-mount installation. The IP40 front protection means it's protected against tools and solid objects larger than 1 mm, but not against water ingress; install in a dry enclosure. Operating temperature range is -25 °C to 70 °C, storage from -40 °C to 80 °C. The 1.2 W maximum power loss is negligible for panel thermal budgeting.