Siemens 5SY6311-7 — 3-pole C-curve MCB at 5 A
The Siemens 5SY6311-7 is a SENTRON miniature circuit breaker, 3-pole, C-curve, rated 5 A at AC. It breaks 6 kA per EN 60898 and 30 kA per IEC 60947-2 — the higher figure governs industrial panel coordination where fault current can exceed the domestic standard. Overvoltage category III and pollution degree 3 mean it's rated for permanent connection to the mains supply inside a distribution board, not just a clean-room subpanel.
Mounting and integration
Snaps onto DIN rail via the quick-assembly system; occupies 3 modular width units (54 mm). Installation depth is 70 mm; overall depth 76 mm. Any mounting position is allowed, and the combined top/bottom terminals accept wiring without reorienting the breaker. Touch protection is built in — no separate finger-safe covers needed for the line side.
Thermal derating and environmental limits
Rated 5 A at 35 °C; at 40 °C the continuous current drops to 4.76 A, at 50 °C to 4.51 A, and at 55 °C to 4.38 A. If the panel ambient runs hot, size the upstream protection for the derated value, not the nameplate 5 A. Ambient range is -40 °C to 75 °C; humidity limit is 95% up to 55 °C, tapering to 35% at 75 °C. Halogen-free and silicon-free construction matters for clean-room or corrosive-environment installs.