Thermal derating and real-world current
The 3VA1150-5EE32-0AA0: The 50 A rating holds flat from 40 °C up to 50 °C — no derating in a warm panel. At 55 °C it drops to 49 A, at 60 °C to 48 A, at 65 °C to 46 A, and at 70 °C to 45 A. If your enclosure sits near a drive or transformer, that 45 A at 70 °C is the number to size against, not the catalog 50 A. Power loss at full load is 14.6 W — negligible for a single breaker, but if you're packing six of these side-by-side in a 600 mm wide panel, the cumulative heat matters for the ventilation budget.