What you're looking at
The Siemens 3VA1140-5EF32-0AH0 is a SENTRON molded case circuit breaker (MCCB) built for line protection — the main disconnect or feeder breaker in a distribution panel. It's a 3-pole unit rated 40 A continuous at 40 °C, with a TM240 thermal-magnetic trip unit inside. The 'TM' means fixed thermal and magnetic settings, no interchangeable trip — what you see is what protects the circuit. Breaking capacity is the headline here: 187 kA at 240 V AC, 121 kA at 415 V, 75.6 kA at 440 V, and still 17 kA up at 690 V. That's a high-interrupting rating for a 40 A frame — it handles fault currents that would vaporize a standard MCB. For a panel builder, this means you can place it close to a large transformer or upstream of a high-fault bus without worrying about cascading failure.
Thermal derating — the real-world rating
The 40 A rating holds flat from 40 °C up to 50 °C ambient — that's the sweet spot for most enclosed panels. At 55 °C it drops to 39 A, at 65 °C to 38 A, and at 70 °C it's 37 A. If your panel runs hot (poor ventilation, high-density layout), you need to account for that 3 A loss at the top end. The power loss at full load is 10.8 W, which is modest for a 40 A MCCB — it won't cook adjacent devices.
Panel fit and auxiliary options
Dimensions: 130 mm tall, 76.2 mm wide, 70 mm deep — a standard 3-pole MCCB footprint that fits most DIN-rail or panel-mount enclosures. It ships with 2 auxiliary switches plus 1 trip alarm switch (HQ type), so you get remote status indication without ordering add-on modules. No undervoltage release, no ground-fault monitoring, no communication function — this is a straightforward thermal-magnetic breaker, not a smart unit.