Siemens SENTRON 5SY6350-8 — 50 A D-Curve MCB for High-Inrush Loads
The D curve means the magnetic trip operates at 10–20× In (500–1000 A), so it rides through the starting surge of a 50 A motor load while still clearing a hard short. Rated for 400 V AC and up to 72 V DC (max per IEC 60947-2), this breaker suits both three-phase AC distribution and DC control circuits. The 3-pole block handles a three-phase feeder in one DIN-rail footprint — 3 width units at 54 mm wide, 76 mm deep, 90 mm tall.
Integration & Mounting Notes
The 54 mm width (3 width units) fits a standard 18 mm/module grid. Combined terminal top and bottom — line and load can enter from either direction, which simplifies busbar routing in a crowded panel. Sealable for lockout/tagout. Halogen-free and silicon-free construction.
Selectivity & Coordination
The D characteristic (10–20× In magnetic trip) is the key selectivity differentiator versus a C-curve breaker. For a 50 A feeder feeding downstream sub-circuits with motor loads, the D curve provides enough magnetic-trip separation to avoid cascading trips on start-up. The 10 kA IEC 60947-2 rating gives SCCR headroom for most industrial panel designs — the 6 kA EN 60898 rating is the residential/commercial floor, but the higher IEC figure governs when the breaker is applied per IEC 60947-2 in an industrial context.