{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY4340-8FA","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY4340-8FA","canonicalUrl":"https://aoctrl.com/siemens/5SY4340-8FA","factsUrl":"https://aoctrl.com/api/mcp/products/5SY4340-8FA","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SY4 series, miniature circuit breaker, 3-pole, 40 A, D tripping characteristic, 10 kA breaking capacity at 400 V AC per EN 60898, 440 V AC multi-phase rated voltage, IP20 with connected conductors, 3 MW units wide.","salesMarkdown":"The Siemens 5SY4340-8FA is a SENTRON miniature circuit breaker (MCB) with a D tripping characteristic, rated 40 A at 35 °C, 3-pole construction, and a 10 kA breaking capacity per EN 60898 at 400 V AC. Multi-phase operating voltage is 440 V AC. The IP20 rating applies once conductors are connected — standard for enclosed panel installation. The 40 A rating holds at 35 °C ambient. At 40 °C it derates to 38.08 A; at 45 °C to 37.08 A; at 50 °C to 36.08 A; at 55 °C to 35 A. Maximum ambient is 75 °C, minimum -40 °C. Depth is 76 mm, height 90 mm, width 54 mm (3 MW). Installation depth 70 mm. Sealable design allows lockout/tagout on the toggle.","metaTitle":"Siemens 5SY4340-8FA SENTRON MCB, 40 A, 3P, D-Curve, 10 kA","metaDescription":"Siemens 5SY4340-8FA SENTRON miniature circuit breaker, 40 A, 3-pole, D tripping characteristic, 10 kA breaking capacity per EN 60898. Active production. Sourced to order against RF","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["3-Pole MCB (DIN Rail)"],"specifications":{"Depth":"76 mm","Width":"54 mm","title":"5SY4340-8FA","Height":"90 mm","Maximum":"75 °C","Minimum":"-40 °C","Sealable":"Yes","description":"Miniature circuit breaker 400 V 10kA, 3-pole, 40A, D=70 mm as counter preliminary miniature circuit breaker","Halogen-Free":"Yes","Silicon-Free":"Yes","Design Of Pole":"3P","Number Of Poles":"3","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":"40 A","protection class IP":"IP20, with connected conductors","Overvoltage Category":"III","Combined Terminal Top":"Yes","Design Of The Product":"As automatic meter","at 35 °C / rated value":"40 A","at 40 °C / rated value":"38.08 A","at 45 °C / rated value":"37.08 A","at 50 °C / rated value":"36.08 A","at 55 °C / rated value":"35 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":"3","Tripping Characteristic Class":"D","Position / Of Power Supply Cord":"Any","according to EN 60898 / rated value":"10 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","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":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/e1dd10680dd76dd0a917c5155942a18e.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=435841&mlfb=5SY4340-8FA"},"ai":{"faq":[{"question":"Where can I buy 5SY4340-8FA and how do I get a price?","answer":"This part is sourced and quoted to order against an RFQ through independent distribution. Submit an RFQ for current availability and pricing — no stock count or price is published here."},{"question":"What is the D-curve on this MCB used for?","answer":"The D tripping characteristic (10 to 20 times In) is designed for circuits with high inrush currents — motor starters, transformers, welding equipment — where a B or C curve would nuisance-trip on startup."},{"question":"What is the breaking capacity of the 5SY4340-8FA?","answer":"10 kA per EN 60898 at 400 V AC. That is the rated short-circuit capacity for the MCB — it can safely interrupt faults up to 10 kA without welding or rupturing."},{"question":"Will 5SY4340-8FA drop into a panel that was specified around 5SY7210-7CC without rewiring?","answer":"Both are 3-pole SENTRON MCBs on the same DIN-rail footprint (3 MW wide), so mechanical fit is identical. The 5SY4340-8FA is a 40 A D-curve; the 5SY7210-7CC is a different rating and curve — verify the branch circuit's load and coordination before swapping."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY4340-8FA","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/5SY4340-8FA 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}}