What this MCCB carries and where it fits
The Siemens SENTRON 3VA2040-7HN36-0AA0 is a 3-pole molded case circuit breaker (MCCB) rated for 40 A continuous current, built around the ETU350 electronic trip unit. That trip unit gives you adjustable overload and short-circuit protection curves — not a fixed thermal-magnetic bimetal — so you can dial in coordination with downstream breakers on a distribution panel or motor control center. Breaking capacity runs 330 kA at 240 V, 242 kA at 415 V and 440 V, 187 kA at 500 V, and 3 kA at 690 V. At 240 V that's enough to clear a fault on the secondary side of a large step-down transformer without the upstream breaker seeing it. The 3 kA at 690 V tells you this isn't the breaker for a 690 V motor feeder — that's a different frame size. Rated insulation voltage is 800 V, so the internal clearances and creepage are sized for 690 V systems with margin. IP40 on the front means it's protected against tools and wires larger than 1 mm — standard for a panel-mounted device, not for washdown areas.
Panel fit and dimensions
The 3VA2040-7HN36-0AA0 measures 105 mm wide, 181 mm high, and 86 mm deep. That's a standard 3-pole MCCB footprint for the 3VA platform — mounts on a DIN rail or panel-mount base. The 86 mm depth means it clears most shallow enclosures, but check the door clearance if you're adding rotary handles or auxiliary contacts.
What the ETU350 trip unit means for coordination
The ETU350 is an electronic trip unit with LSI protection — long-time (overload), short-time (short-circuit with delay), and instantaneous. That short-time delay is the key feature for selective coordination: you can set a delay so a downstream fault clears first, and this breaker only trips if the fault persists. Fixed thermal-magnetic breakers can't do that.