{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY4340-8CV","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY4340-8CV","canonicalUrl":"https://aoctrl.com/siemens/5SY4340-8CV","factsUrl":"https://aoctrl.com/api/mcp/products/5SY4340-8CV","rawCanonicalId":null},"summary":{"shortDescription":"Siemens 5SY4340-8CV, MCB, 3-pole D40, Icu=15kA at 400V, current lifecycle stage.","salesMarkdown":"The Siemens 5SY4340-8CV is a 3-pole miniature circuit breaker with a D40 trip characteristic and a rated ultimate breaking capacity (Icu) of 15 kA at 400 V AC. The D curve means it tolerates the inrush of motor and transformer loads — typically 10 to 20 times rated current — before tripping magnetically, so it's a fit for motor branch circuits, not general lighting or resistive loads where a B or C curve would trip sooner on startup. ## What the ratings mean for fit The 15 kA Icu at 400 V tells you the breaker can safely interrupt a fault current up to that level without welding its contacts or rupturing the housing — critical for panel SCCR compliance when the available fault current at the panelboard is known. The D40 rating (40 A continuous, D-trip) is sized for a motor full-load current around 32–36 A, allowing the magnetic trip to ride out the locked-rotor surge without nuisance tripping. Three-pole construction covers a three-phase load; the neutral is not switched, so this is for a 3-wire delta or a 4-wire wye where the neutral is bonded separately.","metaTitle":"Siemens 5SY4340-8CV MCB, 3P D40, 15kA @ 400V","metaDescription":"Siemens 5SY4340-8CV miniature circuit breaker, 3-pole D40 curve, 15kA breaking capacity at 400V. Current lifecycle stage: active production. Sourced to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Miniature Circuit Breakers (MCB)"],"specifications":{"title":"5SY4340-8CV","description":"MCB Icu=15KA 400V 3P D40","lifecycle_stage":"current"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/35ab4ea4cb64c9184df21c6cfc1de9a2.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=1531601&mlfb=5SY4340-8CV"},"ai":{"faq":[{"question":"What is the breaking capacity of the 5SY4340-8CV?","answer":"The rated ultimate breaking capacity (Icu) is 15 kA at 400 V AC, three-pole. That is the maximum fault current the breaker can safely interrupt under standard test conditions."},{"question":"Where can I buy the 5SY4340-8CV and how is it quoted?","answer":"The 5SY4340-8CV is sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time — no stock count or price is published here."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY4340-8CV","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/5SY4340-8CV 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}}