The Siemens 5SY7103-8 is a 1-pole miniature circuit breaker from the SENTRON 5SY7 series, rated 3 A at 35 °C with a D tripping characteristic. The D-curve means it tolerates inrush currents 10–20× the rated current — the right choice for motor, transformer, or lighting ballast loads where the starting surge would nuisance-trip a B- or C-curve breaker. The 3 A rating at 35 °C is the baseline; at 40 °C it derates to 2.82 A, at 50 °C to 2.62 A, and at 60 °C to 2.41 A, so the ambient temperature inside the enclosure directly governs the continuous load it can carry.
Sealable for panel-lockout procedures. Halogen-free and silicon-free construction avoids outgassing concerns in sealed enclosures or sensitive environments.