It is designed for line protection duty — meaning it sits on the feeder side of a panel, protecting cable and bus from overloads and short circuits, not as a motor-protective device with integrated overload class. At 240 V it interrupts 75.6 kA; at 415 V, 52.5 kA; at 440 V, 32 kA; at 500 V and 690 V, 11.9 kA. For a 40 A frame, those numbers give substantial headroom over typical available fault current in a distribution panel — you are not riding the edge of the rating curve. If your BOM calls for adjustable long-time or short-time pickup, you need the electronic release variant in the 3VA family.
Rated current holds at 40 A from 40 °C through 50 °C, then derates to 39 A at 55–60 °C, 38 A at 65 °C, and 37 A at 70 °C. In a crowded panel with multiple breakers side-by-side, expect the internal temperature to sit above ambient — plan your ganging per Siemens mounting rules to stay within the 40 A rating at your actual enclosure temperature. Dimensions are 70 mm deep, 101.6 mm wide, 130 mm high — a 4-pole MCCB that fits the standard 3VA frame footprint. Maximum power loss is 10.8 W. That is the heat the breaker dissipates at full rated current — factor it into your panel thermal budget, especially if grouping several breakers in a small enclosure.