The Siemens SENTRON 3VA1040-2ED42-0AA0 is a 4-pole molded case circuit breaker rated 40 A continuous at 40 °C, with a TM210 thermal-magnetic release — meaning the thermal pickup is fixed, and the magnetic short-circuit trip is set at 10× In (400 A). It's a line-protection version, so it's built for feeder and distribution duty rather than motor-circuit protection. The interrupting ratings climb to 52.5 kA at 240 V and 32 kA at 415 V, which gives you real fault-clearing headroom in a 400 V distribution panel without worrying about cascading upstream. The 4-pole design lets you switch the neutral, which matters in TN-S or TT systems where you need full isolation. Power loss tops out at 10.8 W, so heat buildup in a crowded enclosure is manageable.
Sizing and derating for real-world temps
Above that it starts to taper: 39 A at 55 °C and 60 °C, 38 A at 65 °C, and 37 A at 70 °C. The TM210 release doesn't need an external adjustment, so what you see on the label is what you get for thermal protection.
Where it fits — dimensions and mounting
That's a 4-inch width on the DIN rail, matching the standard SENTRON 3VA footprint.