{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY4125-8","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY4125-8","canonicalUrl":"https://aoctrl.com/siemens/5SY4125-8","factsUrl":"https://aoctrl.com/api/mcp/products/5SY4125-8","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON miniature circuit breaker, 5SY4125-8, D-curve, 1-pole, 10 kA (EN 60898-1) / 20 kA (IEC 60947-2), 400 V AC, 18 mm wide.","salesMarkdown":"It's rated to clear faults at 10 kA per EN 60898-1 and 20 kA per IEC 60947-2 at 400 V AC, with a DC breaking capacity of 15 kA at 60 V per IEC 60947-2. ## Breaking capacity and standards This MCB carries dual-standard ratings: 10 kA under IEC/EN 60898-1 and 20 kA under IEC 60947-2, both at 400 V AC. At DC, it's rated 15 kA at 60 V (IEC 60947-2). For UL 1077 / CSA C22.2 No. 235 applications, the interrupting capacity is 5 kA. The operating voltage range covers 400 V AC single-phase and 440 V AC multi-phase, with a DC max of 72 V. ## D-curve and deployment context The D characteristic (tripping between 10x and 20x In) suits motor starting, welding circuits, and transformer primaries where the inrush can hit 12–15x full-load current for a few cycles. A B- or C-curve breaker would nuisance-trip on that same surge. Operating temperature range is -40 °C to 75 °C, with humidity derating: max 95% up to 55 °C, then dropping to 35% at 75 °C. It's sealable (provision for a lead seal or lock) and carries IP20 protection with connected conductors. Vibration resistance per IEC 60068-2-6 covers ±1 mm at 5–25 Hz and 50 m/s² at 25–150 Hz — enough for pump skids and conveyor drives that rattle the panel.","metaTitle":"Siemens 5SY4125-8 SENTRON MCB, D-Curve, 1-Pole, 10kA IEC","metaDescription":"Siemens 5SY4125-8 SENTRON miniature circuit breaker, D tripping characteristic, 1-pole, 10 kA (IEC 60898-1) / 20 kA (IEC 60947-2). Active production, sourced to order. Quoted again","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["1-Pole MCB (DIN Rail)"],"specifications":{"Depth":"76 mm","Width":"18 mm","Height":"90 mm","Maximum":"75 °C","Minimum":"-40 °C","Sealable":"Yes","Standard":"IEC / EN 60898-1, IEC / EN 60947-2 / UL1077","Halogen-Free":"Yes","Silicon-Free":"Yes","Design Of Pole":"1P","Number Of Poles":"1","lifecycle_stage":"current","Fastening Method":"Quick assembly system","Mounting Position":"any","at AC rated value":"400 V","at DC rated value":"60 V","Installation Depth":"70 mm","Product Brand Name":"SENTRON","Degree Of Pollution":"3","Product Designation":"Miniature circuit breaker","protection class IP":"IP20, with connected conductors","Overvoltage Category":"III","Combined Terminal Top":"Yes","Combined Terminal Bottom":"Yes","Suitability For Operation":"Mechanical engineering / industry","Neutral Conductor Switching":"No","Number Of Modular Width Units":"1","Position Of Power Supply Cord":"Any","Tripping Characteristic Class":"D","according to EN 60898 rated value":"10 kA","according to IEC 60947-2 rated value":"20 kA","Influence Of The Surrounding Temperature":"max. 95% to 55°C, max. 55% to 70°C, max. 35% to 75°C","Type Of Voltage Of The Operating Voltage":"AC","at DC according to IEC 60947-2 rated value":"15 kA","Value Range Of The Supply Voltage Frequency":"50/60 Hz","operating voltage at DC rated value maximum":"72 V","with multi-phase operation at AC rated value":"440 V","with single-phase operation at AC rated value":"440 V","at AC according to UL 1077 and CSA C22.2 No.235":"5 kA","vibration resistance according to IEC 60068-2-6":"±1mm at 5 to 25Hz; 50m/s² at 25 to 150Hz","Mechanical Service Life (Operating Cycles) Typical":"10 000","Product Extension Installable Supplementary Devices":"Yes","supply voltage with single-phase operation at AC rated value":"230 V","power loss [W] for rated value of the current at AC in hot operating state per pole":"2.1 W"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$13.97","priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/d3d20b687b5798e54d51146afaf9ca6b.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=6306&mlfb=5SY4125-8","alternativesUrl":"https://aoctrl.com/api/mcp/products/5SY4125-8/alternatives.json"},"ai":{"faq":[{"question":"What is the breaking capacity of 5SY4125-8 at 400 V AC?","answer":"10 kA per IEC/EN 60898-1 and 20 kA per IEC 60947-2. For UL 1077 applications, it's 5 kA."},{"question":"What does the D-curve mean for motor loads?","answer":"The D characteristic trips between 10x and 20x rated current, so it handles motor inrush (typically 8–12x FLA) without nuisance tripping. It's the right choice for compressors, pumps, and welding circuits."},{"question":"Will 5SY4125-8 drop into a panel specified for 5SY4140-7 without rewiring?","answer":"Both are 1-pole SENTRON MCBs in the same 18 mm modular width, same DIN-rail mount. The difference is the tripping curve: the 5SY4140-7 uses a different characteristic. If the panel was wired for the same pole count and busbar pitch, the physical swap is straightforward — but verify the curve matches the load before committing."},{"question":"What compliance documentation comes with 5SY4125-8?","answer":"RoHS, REACH, and test certificates for IEC/EN 60898-1, IEC/EN 60947-2, and UL 1077 are available. These are provided with the shipment or on request."},{"question":"Where can I buy 5SY4125-8 and how is it quoted?","answer":"Sourced through independent distribution channels. Quoted to order against an RFQ — availability and current pricing are confirmed at quote time."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY4125-8","citationPolicyUrl":"https://aoctrl.com/llms.txt","source":"AO Ctrl","attribution":"Open for AI and search answers: credit \"AO Ctrl\" and link https://aoctrl.com/siemens/5SY4125-8 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-09-02T08:15:54.622Z","lastPublished":"2026-09-02T08:15:54.622Z","indexable":true}}