The D curve (typically 10–20× In) handles inrush from small transformers, solenoid valves, or motor starters without nuisance tripping — the right choice when the load has a high starting surge but low steady-state draw.
The 5SY4301-8CC11 carries a current-production lifecycle stage, so it remains in active manufacture and standard distribution. No official successor has been issued — the part is the current design.
It accepts solid or stranded conductors from 0.75 to 35 mm² at both top and bottom combined terminals, with a tightening torque of 2.5–3.5 N·m. The installation depth is 70 mm, and the overall depth is 76 mm — check panel clearance if back-mounting. Mounting position is any; the device is sealable and provides touch protection. IP20 applies only with connected conductors.
Rated for ambient temperatures from -40 to +70 °C and storage from -40 to +75 °C, with humidity limits up to 95% at 55 °C. The design is halogen-free and silicon-free, and it is specifically marked for railway applications. The part carries no neutral-conductor switching function — it is a 3-pole device for 3-phase systems without switched neutral.
Multi-phase rating and coordination
In multi-phase operation the rated voltage rises to 440 V AC, which covers the upper end of standard 400 V networks and allows use in 480 V systems with appropriate phase-to-phase coordination. The D-curve selectivity with downstream 1 A MCBs is straightforward — the 10 kA SCCR at 400 V provides adequate headroom for most final sub-circuits in industrial and railway panels.