The Siemens 5SY4210-7CV is a 2-pole miniature circuit breaker with C-curve tripping characteristic, rated 10 A at 35 °C and 440 V AC multi-phase, with a 15 kA breaking capacity per IEC 60947-2.
Thermal derating — the real ampacity
The 10 A rating holds at 35 °C ambient. At 40 °C it derates to 8.89 A, at 45 °C to 8.28 A, at 50 °C to 7.6 A, and at 55 °C to 6.91 A. The breaker is rated for a maximum ambient of 75 °C and a minimum of -40 °C, with humidity limits of 95% up to 55 °C, 55% up to 70 °C, and 35% up to 75 °C.
Vibration and mechanical endurance
Vibration resistance per IEC 60068-2-6: ±1 mm at 5 to 25 Hz, 50 m/s² at 25 to 150 Hz. The quick-assembly fastening system and combined top/bottom terminals simplify panel wiring — strip length and torque are per the terminal marking.