The magnetic short-circuit pickup is adjustable via a rotary dial on the front, which lets you coordinate with downstream breakers without swapping the whole unit.
This breaker carries 187 kA interrupting capacity at 240 V AC, dropping to 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at both 500 V and 690 V. In a 480 V panel (common in North America), the 75.6 kA figure at 440 V is the closest published rating — expect similar performance at 480 V. For a 400 V IEC distribution board, 121 kA gives you headroom for high-fault utility feeds.
Thermal derating — real-world current in a warm panel
At 55 °C it derates to 39 A, at 65 °C to 38 A, and at 70 °C to 37 A. That means in a tightly packed panel running 50 °C internal air, you still get full 40 A. Above that, the thermal element tracks the ambient — no surprise, but worth noting if you're sizing for continuous load near the limit in a hot enclosure.
The 3VA1140 frame measures 101.6 mm wide, 130 mm tall, and 70 mm deep. That 4-inch width is the standard 4-pole MCCB footprint for the 3VA1 frame size — it occupies the same panel cutout as other 3VA1 4-pole units.