The 3-module-width footprint (54 mm) and 70 mm installation depth mean it fits the same cutout as any other 3-pole SENTRON MCB; no panel rework needed if you're swapping from another 3-pole unit in the same family.
Derating and ambient temperature — the real-world current rating
The 40 A nameplate rating holds at 35 °C ambient. Above that, the continuous current must be derated: 38.4 A at 40 °C, 37.6 A at 45 °C, 36.76 A at 50 °C, 35.92 A at 55 °C. If the panel runs hot — say, inside a non-ventilated enclosure near transformers or drives — size the upstream protection or load accordingly. The operating range is -40 °C to 75 °C, with humidity limits: max 95% RH up to 55 °C, then derated to 55% at 70 °C and 35% at 75 °C. That covers outdoor cabinets in cold climates and warm indoor switchgear rooms.
Where it goes and what it guards
This MCB is designed for AC circuits only — the operating voltage type is AC. Typical deployment is in sub-distribution boards for lighting, socket outlets, small HVAC units, and control transformers in mechanical engineering and industrial settings.