{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY4340-8CC","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY4340-8CC","canonicalUrl":"https://aoctrl.com/siemens/5SY4340-8CC","factsUrl":"https://aoctrl.com/api/mcp/products/5SY4340-8CC","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SY4 series, miniature circuit breaker, 3-pole, D characteristic, 40 A rated current, 400 V AC, 10 kA breaking capacity per EN 60898.","salesMarkdown":"Three poles, no neutral switching — it's a straight 3P device for three-phase branch circuits in industrial control panels or distribution boards. Rated breaking capacity is 10 kA per EN 60898, and 5 kA per UL 1077 / CSA C22.2 No. 235. That UL/CSA supplemental-protector rating means it's accepted in North American industrial panels as branch-circuit protection, though not as a full UL 489 listed breaker. The D characteristic governs the magnetic trip threshold: typically 10–20× In (400–800 A instantaneous), so it holds through motor starting without dropping the circuit. If your load is resistive (heaters, lighting), a C curve would suffice and give better selectivity downstream — but for drives, transformers, or high-inrush gear, D is the right call. At 40 A and 400 V AC three-phase, this breaker covers a motor load up to roughly 22 kW (assuming 0.85 PF and 0.9 efficiency). The 440 V rating for both single-phase and multi-phase operation gives headroom on a 400 V nominal system. DC rating maxes at 72 V — not for 125 V DC control buses. Temperature derating matters: the breaker is rated for ambient -40 to 75 °C, but the thermal-magnetic trip calibrates at 30 °C. Above 40 °C, the continuous current capability drops per the influence curve (95% RH at 55 °C, 55% at 70 °C, 35% at 75 °C). In a hot enclosure near a drive or transformer, derate or upsize the frame. Sealable (can be locked in OFF position for lockout/tagout). Touch protection on the terminals means finger-safe to IPXXB when wired.","metaTitle":"Siemens 5SY4340-8CC SENTRON MCB, D Curve, 40 A, 3-Pole","metaDescription":"Siemens 5SY4340-8CC SENTRON miniature circuit breaker, 40 A, 3-pole, D tripping characteristic, 10 kA (EN 60898), 400 V AC. Active production. Quoted to order.","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":"5SY4340-8CC","Height":"90 mm","Maximum":"75 °C","Minimum":"-40 °C","Sealable":"Yes","Rated Value":"50/60 Hz","description":"Miniature circuit breaker 400 V 10kA, 3-pole, D, 40 A","Halogen-Free":"Yes","Silicon-Free":"Yes","Mounting type":"Quick assembly system","Number of poles":"3","Type of voltage":"AC","lifecycle_stage":"current","Mounting position":"any","Installation depth":"70 mm","Product brand name":"SENTRON","Degree of pollution":"3","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","Number of width units":"3","Number of poles / Note":"3P","acc. to DIN EN 61346-2":"F","acc. to DIN EN 81346-2":"F","Combined Terminal Bottom":"Yes","circuit-breaker / Design":"5SY4CC","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","at AC / acc. to UL 1077 and CSA C22.2 No.235":"5 kA","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"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/9fe70d50780694db3ca07e255849a3f6.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=141712&mlfb=5SY4340-8CC"},"ai":{"faq":[{"question":"What is the breaking capacity of the 5SY4340-8CC?","answer":"10 kA per EN 60898 at 400 V AC, and 5 kA per UL 1077 / CSA C22.2 No. 235. The UL/CSA rating is the one to verify against your panel's available fault current if the installation is in North America."},{"question":"Does the 5SY4340-8CC switch the neutral?","answer":"No. It is a 3-pole device with no neutral switching function. For a 3P+N application you would need a separate neutral bar or a 4-pole variant."},{"question":"Where can I buy the 5SY4340-8CC?","answer":"Sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time."},{"question":"How does the 5SY4340-8CC compare to the 5SY7140-8CC?","answer":"The 5SY7140-8CC is a functionally similar SENTRON MCB with the same 40 A, D curve, and 3-pole configuration, but it belongs to a different series (5SY7 vs 5SY4). The 5SY4340-8CC is the current-production design (5SY4CC); the 5SY7 series is an older generation. Both share the same DIN-rail footprint and terminal layout, so one can typically replace the other without rewiring, but verify the breaking capacity rating on the nameplate matches your coordination study."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY4340-8CC","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/5SY4340-8CC 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}}