The Siemens SENTRON 3VA1140-3EF32-0AE0 is a 3-pole molded case circuit breaker rated 40 A at 40 °C, with a TM240 thermal-magnetic release designed for line protection in distribution panels. Its interrupting ratings climb to 75.6 kA at 240 V and 52.5 kA at 415 V, so it handles high-fault scenarios common on industrial mains without needing an upstream current-limiting fuse. The 800 V rated insulation voltage means it's comfortable on 480 V or 600 V systems too — just watch the 690 V interrupting curve drops to 11.9 kA.
It only starts to taper above 55 °C — 39 A at 55 °C, 38 A at 65 °C, and 37 A at 70 °C (–). That's a shallow derating curve; in a sealed, warm panel you lose only 3 A at the top end. The maximum power loss is 10.8 W, which is modest for a 40 A frame — helps keep internal temperatures down.
The TM240 release is fixed, so no field-adjustable thermal dial; you set the trip curve at ordering.