The Siemens 5SY4204-7CV is a 2-pole miniature circuit breaker with C-curve tripping characteristic, rated 4 A at AC and carrying a 15 kA breaking capacity per IEC/EN 60947-2 — that's the fault-clearing capability you need for downstream coordination in a 440 V AC distribution panel.
Temperature derating and environmental limits
The breaker's rated current of 4 A at 35 °C derates to 3.71 A at 40 °C, 3.55 A at 45 °C, 3.4 A at 50 °C, and 3.22 A at 55 °C — so if your panel ambient runs at 50 °C, size the load to stay under 3.4 A per pole. The operating temperature range spans -40 °C to 75 °C, and the unit withstands vibration per IEC 60068-2-6 (±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz).