What it is and what it does
The Siemens 3VA1140-6EF36-0AH0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection — the primary role is to clear faults on distribution feeders and branch circuits before they damage downstream gear or start a fire. It carries a 40 A continuous rating at 40 °C, and the thermal-magnetic TM240 release means the thermal element handles overloads and the magnetic element handles short-circuits — no electronic adjustment, just reliable bimetal and solenoid action. Breaking capacity is the headline: 220 kA at 240 V, 154 kA at 415 V, 121 kA at 440 V, and still 17 kA at 690 V. That 220 kA figure at 240 V is what lets this breaker sit on a high-fault panelboard or transformer secondary without needing a current-limiting fuse upstream — it self-protects. Rated insulation voltage is 800 V.
Thermal derating and real-world current
The 40 A rating holds from 40 °C through 50 °C. At 55 °C it drops to 39 A, at 65 °C to 38 A, and at 70 °C to 37 A. If your panel runs hot — say 55 °C ambient inside the enclosure — you lose 1 A of headroom. That matters when sizing for a continuous load near the limit. Power loss at full load is 10.8 W maximum.
Mounting and integration
Three-pole, 70 mm deep, 76.2 mm wide, 130 mm tall. The width is a standard 3-inch (76.2 mm) footprint — drops into a 3-pole MCCB slot on a DIN rail or panel-mount base without adapters. Comes with two auxiliary switches and one trip alarm switch (HQ type) built in — that gives you remote status for open/closed and tripped conditions without adding external modules. No undervoltage release, no ground-fault monitoring, no communication function. This is a plain-vanilla thermal-magnetic breaker — no electronics to fail, but also no remote trip or GFCI capability.