That 400 A holds from 40 °C all the way up to 50 °C — no derating needed until you cross 55 °C, where it steps down to 385 A, then 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. Breaking capacity is where this breaker earns its keep. At 240 V it handles 187 kA, at 415 V it's 121 kA, at 440 V it's 55 kA, at 500 V it's 36 kA, and at 690 V it's 7.5 kA. That kind of headroom on a 400 A frame means it can sit upstream of a big transformer or feed a high-fault bus without worrying about cascading failure. The 3-pole design handles three-phase loads straight out of the box. The ETU320 is an electronic trip unit with adjustable long-time pickup (Ir) from 0.5 to 17 seconds and a short-time delay. That gives you selectivity coordination with downstream feeders — you can set it to ride through inrush without nuisance tripping. No communication module on this version, but it accepts a motor drive accessory if you need remote operation.
The 3VA2340-5HL32-0BB0 measures 248 mm tall, 138 mm wide, and 110 mm deep — about 9.8 by 5.4 inches. It fits standard SENTRON panelboards or DIN-rail adapters.