The headline number here is the breaking capacity: 85 kA Icu at 500 V AC 50/60 Hz. That's your continuous current rating — the breaker will carry 40 A all day in a 40 °C panel. Above that, the thermal element starts its inverse-time curve. The mechanical durability is rated at 20,000 cycles, and the electrical durability varies by load: 20,000 cycles at 440 V at half-rated current, 10,000 at full 440 V In, and 5,000 at 690 V In. That's a solid lifespan for a panel breaker that isn't switched daily.
The 40 A rating and the 85 kA breaking capacity at 500 V are the two specs that decide fit. The 3-pole (3P) configuration with 3 protected poles (3D) means all three phases are switched and protected. It mounts on a backplate, accepts front-connect wiring, and has a 35 mm connection pitch — standard for panel layouts. The IP40 enclosure rating and IK07 impact resistance mean it's suited for indoor panel installation where occasional tool drops or dust ingress are a concern. Operating altitude is 0–2000 m without derating, 2000–5000 m with derating, so it's fine for most plant locations.