It is designed for line protection — the primary feeder or main disconnect in a distribution panel, not for motor or generator protection. The ETU340 release gives you adjustable long-time, short-time, instantaneous, and ground-fault protection curves, which means you can coordinate it downstream of a larger feeder breaker and upstream of branch panel MCCBs without nuisance tripping.
This breaker carries a rated ultimate short-circuit breaking capacity (Icu) of 440 kA at 240 V AC, 330 kA at 415 V and 440 V, 220 kA at 500 V, and 52.5 kA at 690 V. At 690 V, the 52.5 kA rating still covers most industrial motor control center bus faults. The 5 500 A minimum and maximum short-time withstand (Icw) rating tells you the breaker can hold closed under fault for at least the short-time delay setting, which is essential for selective coordination.
Temperature derating — don't size by the 40 °C number alone
At 55 °C it derates to 477 A, at 60 °C to 455 A, at 65 °C to 432 A, and at 70 °C to 410 A. The maximum power loss is 99 W — that's the heat you need to vent through the enclosure. Panel builders should account for this in the thermal budget, especially in a sealed NEMA 12 enclosure.
That 184 mm width across four poles is wider than a typical 3-pole MCCB of the same frame — verify the DIN-rail or mounting-plate space before committing the panel layout.