Siemens 3VA2140-5MN32-0AD0 is a SENTRON molded case circuit breaker (MCCB) built for motor protection duty. It's a 3-pole unit rated 40 A continuous current across the full ambient range from 40 °C to 70 °C — no derating needed up to that ceiling. Breaking capacity hits 121 kA at 415 V, which puts it in the high-interrupting class for industrial distribution panels feeding motor control centers.
What the ratings mean for fit
The 40 A rating is flat from 40 °C to 70 °C, so if you're stuffing this into a hot panel next to drives or transformers, you don't lose headroom. That's unusual for a compact MCCB — many competitors start derating above 40 °C. The 121 kA at 415 V means it can sit upstream of a group of motor starters without needing a current-limiting fuse ahead of it, as long as the available fault current at the panel doesn't exceed that figure. At 240 V it's rated 187 kA, so it handles utility-transformer secondary faults cleanly. Phase failure detection is built in — that's the motor protection variant's job: if one phase drops, the breaker trips before single-phasing cooks the winding. No undervoltage release, no shunt trip, no communication module on this order code; it's a straight thermal-magnetic motor protector with auxiliary switches (3 HQ aux switches included per). The basic switch inside is 3VA21405MN320AA0, so if you're swapping just the internal mechanism, that's the spare part number.
Dimensions and panel fit
Footprint is 105 mm wide, 181 mm tall, 86 mm deep. That's a standard SENTRON 3VA2 frame size — mounts on DIN rail or direct panel via screw terminals. The 105 mm width means it occupies three 35 mm module spaces if you're laying out a DIN-rail enclosure. Depth of 86 mm leaves room for rear-access cabling in a 200 mm deep enclosure without forcing a right-angle bend on the incoming lugs.
Power loss and thermal management
Maximum power loss is 1.6 W at rated load. That's low enough that you don't need forced ventilation in a typical panel — the heat rise from this breaker alone won't push the internal ambient past the 70 °C operating limit. Storage range is -40 °C to 80 °C, so it tolerates warehouse extremes without issue.