The Siemens SENTRON 5SY7108-8 is a 1-pole miniature circuit breaker with D-curve tripping, rated 8 A at 35 °C and 400 V AC. It provides 15 kA breaking capacity per EN 60898 and 30 kA per IEC 60947-2, with a DC rating of 15 kA per IEC 60947-2. That 30 kA IEC figure gives you headroom for high-fault industrial panels where the utility transformer is close — the EN rating is the standard residential/commercial floor, but the IEC rating is what matters for selectivity studies in an industrial distribution board. At 8 A, this is sized for a small motor circuit or a control transformer primary, not a main feeder.
Panel fit & environment
Occupies 1 modular width unit (18 mm) on DIN rail. Mount in any position; fastens via the quick-assembly system (snap-on). IP20 with connected conductors — enclosed in a panel, not open-terminal. Current derates above 35 °C: 7.26 A at 45 °C, 6.99 A at 50 °C, 6.72 A at 55 °C, 6.43 A at 60 °C. If your panel ambient runs 50 °C, plan for the 7 A effective rating, not the 8 A nameplate. Halogen-free and silicon-free construction — important for clean-room or semiconductor-adjacent installations where outgassing contaminates processes.
Sealable (can be locked in OFF position for LOTO). Touch-protected terminals. Combined terminal top and bottom accept standard wiring. Rated for mechanical engineering/industrial operation per the suitability listing. The part carries designations per IEC 81346-2 and DIN EN 61346-2 (function code F).