{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY4240-8FA","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY4240-8FA","canonicalUrl":"https://aoctrl.com/siemens/5SY4240-8FA","factsUrl":"https://aoctrl.com/api/mcp/products/5SY4240-8FA","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SY4240-8FA, 2-pole miniature circuit breaker, D tripping characteristic, 40 A rated current, 10 kA breaking capacity at 400 V AC, 2 width units (36 mm).","salesMarkdown":"The Siemens 5SY4240-8FA is a 2-pole miniature circuit breaker from the SENTRON series, rated 40 A with a D tripping characteristic. The 10 kA breaking capacity at 400 V AC (per EN 60898) tells you it can safely interrupt a fault up to that level without welding the contacts or cascading upstream. Mounts on DIN rail, occupies 2 width units (36 mm), and accepts conductors up to 35 mm² solid or stranded. The D-curve's magnetic trip threshold (10–20× In) is what keeps it from dropping out on motor start — a 7.5 kW motor drawing 120 A locked-rotor for 200 ms stays below the instantaneous trip point, while a hard short still clears in under 10 ms. The 10 kA SCCR at 400 V means the breaker itself is rated to interrupt a 10 kA prospective fault current; if your panel's available fault current exceeds that, you need an upstream current-limiting device to coordinate. The 2-pole configuration switches both phase conductors simultaneously — no neutral switching (confirms neutral conductor switching is not a function of this unit). Depth is 76 mm, installation depth 70 mm — leaves 6 mm clearance behind the rail for wiring. Height 90 mm, width 36 mm (2 width units). Terminal torque spec is 3.5 N·m; accepts 0.75 to 35 mm² solid or stranded. Ambient operating range -25 to +55 °C; storage range -40 to +75 °C. Halogen-free and silicon-free construction. Sealable for tamper-proofing in metering or rental applications.","metaTitle":"Siemens 5SY4240-8FA SENTRON MCB, 2P D 40 A 10 kA","metaDescription":"Siemens 5SY4240-8FA SENTRON miniature circuit breaker, 2-pole, D-curve, 40 A, 10 kA breaking capacity per EN 60898. Active production. Sourced to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["2-Pole MCB (DIN Rail)"],"specifications":{"Depth":"76 mm","Solid":"0.75 ... 35 mm²","Width":"36 mm","title":"5SY4240-8FA","Height":"90 mm","Sealable":"Yes","Stranded":"0.75 ... 35 mm²","Rated Value":"50/60 Hz","description":"Miniature circuit breaker 400 V 10kA, 2-pole, 40A, D=70 mm as counter preliminary miniature circuit breaker","Halogen-Free":"Yes","Silicon-Free":"Yes","Mounting type":"Quick assembly system","During Storage":"-40 ... +75 °C","Number of poles":"2","Type of voltage":"AC","lifecycle_stage":"current","Mounting position":"any","Installation depth":"70 mm","Product brand name":"SENTRON","Ambient temperature":"-25 ... +55 °C","Product designation":"Miniature circuit breaker","Protection class IP":"IP20, with connected conductors","at AC / rated value":"400 V","Overvoltage category":"III","Combined Terminal Top":"Yes","Design of the product":"As automatic meter","Number of width units":"2","Number of poles / Note":"2P","acc. to DIN EN 81346-2":"F","Combined Terminal Bottom":"Yes","Suitability for operation":"Mechanical engineering / industry","Current / at AC / rated value":"40 A","Tripping characteristic class":"D","at DC / rated value / maximum":"72 V","acc. to EN 60898 / rated value":"10 kA","Position / of power supply cord":"Any","Product feature / Touch protection":"Yes","Influence of the surrounding temperature":"max. 95% to 55°C, max. 55% to 70°C, max. 35% to 75°C","Tightening torque / with screw-type terminals":"3.5 N·m","Product function / neutral conductor switching":"No","with multi-phase operation / at AC / rated value":"440 V","with single-phase operation / at AC / rated value":"440 V","Mechanical service life (switching cycles) / typical":"10 000","Tightening torque [lbf·in] / with screw-type terminals":"31 lbf·in","AWG number / as coded connectable conductor cross section":"18 ... 4"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/e9cf402fbdc6bb0eeca046d56f62e11c.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=7260&mlfb=5SY4240-8FA"},"ai":{"faq":[{"question":"What is the 5SY4240-8FA's breaking capacity?","answer":"10 kA at 400 V AC per EN 60898. That is the maximum fault current it can safely interrupt at that voltage."},{"question":"Where can I buy the 5SY4240-8FA?","answer":"Sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing confirmed at quote time."},{"question":"What is the difference between the 5SY4240-8FA and the 5SY7140-8CC?","answer":"The 5SY7140-8CC is a 1-pole + N breaker with a C-curve, also 40 A. The 5SY4240-8FA is a 2-pole D-curve. The D-curve handles higher inrush (motor/transformer loads) while the C-curve is for general-purpose inductive loads. The 5SY4240-8FA will not drop into a panel wired for the 5SY7140-8CC without rewiring because the pole count and busbar arrangement differ."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY4240-8FA","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/5SY4240-8FA when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-08-11T15:51:03.652Z","lastPublished":"2026-08-11T15:51:03.652Z","indexable":true}}