Siemens 5SY4508-5 — SENTRON MCB for panel builders and spares buyers
The Siemens 5SY4508-5 is a 1P+N miniature circuit breaker from the SENTRON series, switching both phase and neutral in a two-module (36 mm wide) package. It carries characteristic A — the fast-trip curve that opens within a few cycles on moderate overloads, suited for protecting semiconductor circuits, control transformers, or sensitive loads where a B-curve would let too much energy through before tripping. Rated breaking capacity is 10 kA per IEC 60898-1 and 20 kA per IEC 60947-2 at 230 VAC, with a DC rating of 15 kA at 60 V per IEC 60947-2. Under UL 1077 it carries 5 kA — enough for most North American supplementary-protection applications. The 76 mm depth (70 mm installation depth) fits standard DIN-rail enclosures with room for wiring. Lifecycle status is current production, so this is a straightforward BOM-line fill — no last-time-buy scramble. Sourced and quoted to order through independent distribution; availability and current pricing confirmed at quote time.
What the ratings mean for fit
Characteristic A trips at 2–3× rated current — faster than the more common B (3–5×) or C (5–10×) curves. That matters when the load is a rectifier input, a UPS bypass, or a control-circuit supply where a short spike from a transformer inrush could nuisance-trip a slower breaker. The 10 kA SCCR at 230 VAC (IEC 60898-1) means it safely interrupts faults up to that level without cascading upstream; the 20 kA rating under IEC 60947-2 gives additional headroom for industrial panel designs that spec to the higher standard. The 1P+N design (two poles, one protected phase plus switched neutral) is common in single-phase final subcircuits where the neutral must be disconnected for isolation. Neutral conductor switching is confirmed, so the breaker opens both poles simultaneously. Rated for pollution degree 3 and overvoltage category III — standard for fixed-installation distribution boards in industrial environments. The IP20 rating (with connected conductors) is typical for enclosed panel mounting; no washdown rating, so keep it behind a gland plate.
Panel integration and environment
Mounts on DIN rail via the quick-assembly system — snaps on, no tools. Two modular width units (36 mm) occupy two slots in a standard distribution board. Any mounting position is allowed, which simplifies layout in tight enclosures. Ambient temperature range is -40 to 75 °C, with humidity derating above 55 °C: max 95% RH at 55 °C, 55% at 70 °C, 35% at 75 °C. Vibration resistance per IEC 60068-2-6: ±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz — enough for machine-mounted panels but not for direct engine mounting without additional damping. Sealable design (provision for a lead seal or lockout tag) supports lockout/tagout procedures. Halogen-free and silicon-free construction matters for clean-room or high-reliability environments where outgassing could contaminate contacts or optics.
Compliance and documentation
Certified to IEC/EN 60898-1 (domestic-style MCB) and IEC/EN 60947-2 (industrial MCCB standard), plus UL 1077 for North American supplementary protection. CSA C22.2 No.235 also listed. The dual-standard rating means the same part can be specified for panels destined for both IEC and UL markets, simplifying BOM consolidation. The manufacturer provides the standard declaration of conformity, CE marking, and the full IEC/UL test reports. RoHS and REACH compliance documentation is available on request through the supply channel.