That 800 A holds flat from 40 °C through 60 °C — per the datasheet, it derates to 767 A at 65 °C and 703 A at 70 °C, so the thermal margin is there for a warm enclosure if you keep ambient under 60 °C. The interrupting capacity tells you what fault it can clear: 187 kA at 240 V, 121 kA at 415 V, and 53 kA at 690 V. The ETU550 electronic trip unit gives you adjustable response times: short-time delay tsd from 0.05 s to 0.5 s, and long-time delay tr from 0.5 s to 25 s. That lets you coordinate selectively with downstream breakers — set the tsd long enough to ride through a motor start inrush without nuisance tripping. The adjustable current Ir goes up to 800 A, matching the frame rating.
Dimensions are 210 mm wide, 320 mm high, 120 mm deep — that is 8.3 by 12.6 by 4.7 inches. The IP40 front protection means it is splash-safe on the operator face but not sealed for washdown; mount it inside a cabinet with a door.