{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY4450-8","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY4450-8","canonicalUrl":"https://aoctrl.com/siemens/5SY4450-8","factsUrl":"https://aoctrl.com/api/mcp/products/5SY4450-8","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SY4450-8, 4-pole miniature circuit breaker, 50 A rated current, D tripping characteristic, 10 kA / 15 kA breaking capacity, 4 MW DIN-rail mount.","salesMarkdown":"## 50 A D-curve for motor and transformer circuits The Siemens 5SY4450-8 is a 4-pole miniature circuit breaker rated 50 A with a D tripping characteristic, meaning it tolerates the high inrush currents of motor starters, transformers, and welding equipment without nuisance tripping — the D curve trips at 10–20× rated current, so a 50 A breaker holds a 500–1000 A inrush for the brief start-up period. Breaking capacity is 10 kA per EN 60898-1 and 15 kA per IEC 60947-2 / UL 1077 — the higher figure applies when the breaker is specified as a supplementary protector under UL 1077, giving headroom for industrial panel fault currents. At 40 °C ambient the 50 A rating derates to 48 A; at 50 °C it drops to 45.95 A, and at 60 °C to 43.8 A — if the panel runs warm, size the breaker for the actual ambient, not the nameplate 50 A. The breaker is rated for ambient temperatures from -40 °C to 75 °C, with humidity limits of 95 % up to 55 °C, tapering to 35 % at 75 °C — this covers outdoor enclosures in cold climates and warm indoor switchgear alike.","metaTitle":"Siemens 5SY4450-8 4-Pole MCB, 50 A D Curve","metaDescription":"Siemens 5SY4450-8 SENTRON 4-pole MCB, 50 A, D tripping characteristic. Breaking capacity 10 kA (EN 60898) / 15 kA (IEC 60947-2). Active production.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Miniature Circuit Breakers (MCB)"],"specifications":{"Depth":"76 mm","Width":"72 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":"4P","Number Of Poles":"4","lifecycle_stage":"current","Fastening Method":"Quick assembly system","Mounting Position":"any","Installation Depth":"70 mm","Product Brand Name":"SENTRON","Degree Of Pollution":"3","Product Designation":"Miniature circuit breaker","at AC / rated value":"50 A","protection class IP":"IP20, with connected conductors","Overvoltage Category":"III","Combined Terminal Top":"Yes","according to EN 61346-2":"F","at 35 °C / rated value":"50 A","at 40 °C / rated value":"48 A","at 45 °C / rated value":"47 A","at 50 °C / rated value":"45.95 A","at 55 °C / rated value":"44.9 A","at 60 °C / rated value":"43.8 A","Combined Terminal Bottom":"Yes","according to IEC 81346-2":"F","Suitability For Operation":"Mechanical engineering / industry","Neutral Conductor Switching":"No","Number Of Modular Width Units":"4","Tripping Characteristic Class":"D","Position / Of Power Supply Cord":"Any","according to EN 60898 / rated value":"10 kA","according to IEC 60947-2 / rated value":"15 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","Value Range / Of The Supply Voltage Frequency":"50/60 Hz","at DC / according to IEC 60947-2 / rated value":"15 kA","with multi-phase operation / at AC / rated value":"440 V","operating voltage / at DC / rated value / maximum":"72 V","vibration resistance / according to IEC 60068-2-6":"±1mm at 5 to 25Hz; 50m/s² at 25 to 150Hz","with single-phase operation / at AC / rated value":"440 V","Mechanical Service Life (Switching Cycles) / Typical":"10 000"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$134.62","priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/2f2d9fe6a1095ae755d4590d56b00974.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=81614&mlfb=5SY4450-8","alternativesUrl":"https://aoctrl.com/api/mcp/products/5SY4450-8/alternatives.json"},"ai":{"faq":[{"question":"Does the 5SY4450-8 come with seals?","answer":"Yes, the breaker is sealable — it accepts a sealing cap or wire seal over the toggle to prevent unauthorized operation after commissioning."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY4450-8","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/5SY4450-8 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}}