What it is and what it does
The Siemens 3VA1140-5EF46-0AA0 is a SENTRON molded case circuit breaker (MCCB) built for line protection — it sits in the main or feeder position of a distribution panel and clears faults fast enough to protect downstream gear. Four poles, rated 40 A at 40 °C, with a TM240 thermal-magnetic release that handles overloads and short-circuits without an external trip unit. Breaking capacity is the headline: 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 500 V and 690 V. That 187 kA figure means it can interrupt a massive fault current at 240 V without welding contacts or rupturing the case — critical for high-fault installations like industrial substations or large motor control centers. Rated insulation voltage is 800 V. Power loss maxes at 10.8 W.
Sizing and derating
Current rating holds flat at 40 A from 40 °C up to 50 °C. At 55 °C it drops to 39 A, at 65 °C to 38 A, and at 70 °C to 37 A. That's a shallow derating curve — you can push ambient to 50 °C without losing ampacity, which buys you flexibility in a warm panel or near a heat source. Operating temperature range is -25 °C to 70 °C; storage from -40 °C to 80 °C. The storage range tells you it can sit in an unheated warehouse or truck without damage — the operating limit is what governs running conditions.
Panel fit and wiring
Dimensions: 70 mm deep, 101.6 mm wide, 130 mm tall. That 101.6 mm width is exactly 4 inches. Front protection is IP40 — no ingress of tools or wires larger than 1 mm, but not sealed against dust or water. Fine for a clean indoor panel; don't mount it in a washdown zone without a separate enclosure.