The Siemens SENTRON 5SY7204-8 is a 2-pole miniature circuit breaker (MCB) with a D tripping characteristic, rated 4 A at AC 50/60 Hz.
Where it fits and how it mounts
Thermal derating and environmental range
The 4 A rating holds at 35 °C ambient. Above that, you must derate: 3.76 A at 40 °C, 3.63 A at 45 °C, 3.5 A at 50 °C, 3.36 A at 55 °C, and 3.22 A at 60 °C. If the panel runs hot — near a drive or transformer — size the breaker for the actual ambient, not the base rating. The operating range spans -40 °C to 75 °C, with humidity limits of 95% up to 55 °C, 55% up to 70 °C, and 35% up to 75 °C.