Siemens SENTRON 5SY4413-8 — 4-pole D-curve MCB, 13 A
The Siemens SENTRON 5SY4413-8 is a 4-pole miniature circuit breaker with a D tripping characteristic, rated 13 A at AC and 50/60 Hz. It's designed for branch-circuit protection in industrial control panels, particularly where high inrush currents from motor or transformer loads are expected — the D-curve holds through the start-up surge without nuisance tripping, then clears fast on a hard fault. That 20 kA IEC rating gives headroom for higher-fault installations — useful when the panel sits close to a large transformer or the supply-side SCCR is above 10 kA.
Installation depth is 70 mm — the extra 6 mm accounts for the terminal screws and wire bend radius. Mounts in any position, quick-assembly system snaps onto the DIN rail without tools.
The 13 A rating is at 35 °C ambient. At 40 °C it's 12.38 A, at 50 °C it's 11.73 A, and at 60 °C it drops to 11.02 A. If the panel runs hot — say 55 °C inside the enclosure — the breaker is good for 11.38 A continuous. That's the number to use for the BOM, not the 13 A nameplate. The ambient influence spec also limits humidity: 95% up to 55 °C, then derated to 55% at 70 °C and 35% at 75 °C.