That 400 A is the full-load handle rating — it carries that current indefinitely in a 40 °C ambient without tripping. Above 55 °C you need to derate: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. Breaking capacity is the other headline. At 240 V it interrupts 187 kA — that's high enough for most service-entrance and large feeder applications. At 415 V it's still 121 kA, and at 690 V it drops to 7.5 kA. This is a line-protection design, meaning the trip curve and thermal-magnetic or electronic trip unit are set for protecting cables and busbars, not motor overloads. The basic switch supplied is 3VA2340-5HN32-0AA0.
Mounting dimensions and panel fit
If you're swapping into an existing panel, check the gland-plate cutout and the busbar spacing against the 110 mm depth; the undervoltage release module adds a few mm behind the breaker body.