Sourcing Decision – Active Production, Steady Supply
The 5SY4250-8 is a current-production Siemens SENTRON miniature circuit breaker, standard catalog item with broad channel availability – no lifecycle risk for new BOM builds. Rated 50 A (AC) with D-curve. Breaking capacity: 10 kA and 15 kA. Derate: continuous rating drops to 42.4 A. Case is 36 mm wide, 76 mm deep, mounts in any orientation.
Thermal Management – Ambient Matters
Carries 47.6 A, 45.1 A, and 42.4 A at higher ambients. For 50 A nominal load, lower ambient required. Ambient humidity limit is 95% at 55 °C, tapering to 35% at 75 °C – typical for sealed enclosures with no condensation.
Cross-Reference vs. 5SY4263-5 – Same Footprint, Different Load
Same D-curve, 2-pole, width, and breaking capacity. Higher rating; confirm load at or below 50 A.
Lifecycle & Compliance – No Phase-Out Risk
Current production; no end-of-life notice. Compliance declarations for RoHS, REACH, and UL are available.