It's designed for line protection — the primary role of a main breaker on a distribution panel or a large motor branch circuit. The ETU320 gives you adjustable long-time and short-time pickup, plus instantaneous and ground-fault (if enabled), so you can coordinate selectively downstream without nuisance trips. The interrupting capacity is what you size a breaker for: 242 kA at 240 V, 187 kA at 415 V and 440 V, 121 kA at 500 V, and 7.5 kA at 690 V. At 400 V class, 187 kA is high-end — it handles large transformer-fed faults without cascading upstream. The 690 V figure (7.5 kA) is lower, but that's typical for a 400 A frame at high voltage; most applications at 690 V are smaller sources. Thermal derating is published stepwise: full 400 A up to 50 °C ambient, then 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C.
The 3VA2340-6HL32-0AA0 measures 248 mm high by 138 mm wide by 110 mm deep. Maximum power loss is 96 W at rated current. That's within the typical heat budget for a 400 A breaker, but if you're packing multiple breakers in a small enclosure, factor that into the ventilation calculation. The storage range is wider than operation — that's the handling and shipping limit, not the running condition.