The 5SY4203-7CC11 is a current-production SENTRON miniature circuit breaker (MCB) — 2-pole, C-curve, rated 3 A at 400 V AC, with a 10 kA breaking capacity tested to EN 60898. Rated for 50/60 Hz, overvoltage category III, and energy limiting class 3, which tells you it limits let-through energy well enough to protect downstream equipment in a distribution board.
Termination and wiring
Sealable, touch-protected, halogen-free and silicon-free — relevant for environments where outgassing contaminates optics or contacts. No neutral switching (2-pole, both poles are phase).