{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY8340-8BB08","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY8340-8BB08","canonicalUrl":"https://aoctrl.com/siemens/5SY8340-8BB08","factsUrl":"https://aoctrl.com/api/mcp/products/5SY8340-8BB08","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SY8340-8BB08, miniature circuit breaker, 3-pole, D tripping characteristic, 25 kA breaking capacity at 400 V AC per IEC 60947-2, magnetic-only trip, 3 modular width units.","salesMarkdown":"The magnetic-only trip (no thermal bimetal) means it reacts solely to short-circuit currents, not overloads, so it's paired with a separate overload relay or motor-protective device. IP20 with connected conductors — standard for panelboard use, not for wet environments. The 25 kA rating at 400 V AC (IEC 60947-2) is the headline number. For UL 1077 / CSA C22.2 No. 235 applications, the rating drops to 5 kA — a common derating when moving from IEC to North American supplementary protector standards. If your panel SCCR calculation depends on this device, the 5 kA figure is the binding limit for UL-listed assemblies. That's higher than a B or C curve, so it won't nuisance-trip on motor start or capacitor bank inrush. But it also means the let-through energy (I²t) is higher during a fault — verify downstream cable and device withstand if coordinating with a smaller branch. ## Panel integration Sealable design allows lockout/tagout provisions. ## Environmental and electrical margins Humidity derating applies above 55 °C: max 95% RH up to 55 °C, then 55% RH to 70 °C, then 35% RH to 75 °C. Vibration resistance per IEC 60068-2-6: ±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz — survives normal machine vibration but not continuous high-frequency shaker tables. For a 3-pole breaker that's 9 W total — negligible for thermal budgeting in most panels, but worth summing if you have dozens of breakers in a sealed enclosure.","metaTitle":"Siemens 5SY8340-8BB08 SENTRON MCB, 3P, D Curve, 25kA @ 400V","metaDescription":"Siemens SENTRON 5SY8340-8BB08 miniature circuit breaker, 3-pole, D tripping characteristic, 25 kA breaking capacity at 400 V AC per IEC 60947-2. Active production, sourced to order","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["3-Pole MCB (DIN Rail)"],"specifications":{"Depth":"76 mm","Width":"54 mm","title":"5SY8340-8BB08","Height":"90 mm","Maximum":"75 °C","Minimum":"-40 °C","Sealable":"Yes","description":"Miniature circuit breaker 400 V 25kA, 3-pole, 40A, D=70 mm only magnetic tripping","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","at AC rated value":"400 V","Installation Depth":"70 mm","Product Brand Name":"SENTRON","Degree Of Pollution":"3","Product Designation":"Miniature circuit breaker","protection class IP":"IP20, with connected conductors","Overvoltage Category":"III","Combined Terminal Top":"Yes","Design Of The Product":"Only magnetic tripping operation","Combined Terminal Bottom":"Yes","Suitability For Operation":"Mechanical engineering / industry","Neutral Conductor Switching":"No","Number Of Modular Width Units":"3","Position Of Power Supply Cord":"Any","Tripping Characteristic Class":"D","according to IEC 60947-2 rated value":"25 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","operating voltage at DC rated value maximum":"72 V","with multi-phase operation at AC rated value":"440 V","with single-phase operation at AC rated value":"440 V","at AC according to UL 1077 and CSA C22.2 No.235":"5 kA","vibration resistance according to IEC 60068-2-6":"±1mm at 5 to 25Hz; 50m/s² at 25 to 150Hz","Mechanical Service Life (Operating Cycles) Typical":"10 000","Product Extension Installable Supplementary Devices":"Yes","power loss [W] for rated value of the current at AC in hot operating state per pole":"3 W"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/00aee9e9d042b50de73790f228acc3fe.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=425910&mlfb=5SY8340-8BB08"},"ai":{"faq":[{"question":"What is the breaking capacity of the 5SY8340-8BB08?","answer":"25 kA at 400 V AC per IEC 60947-2, and 5 kA per UL 1077 / CSA C22.2 No. 235."},{"question":"Where can I buy the 5SY8340-8BB08?","answer":"Sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing confirmed at quote time."},{"question":"What does the D tripping characteristic mean for this MCB?","answer":"The D curve trips magnetically at 10–20 times rated current, making it suitable for loads with high inrush like motors and transformers. It is a magnetic-only trip — no thermal overload element — so it must be paired with a separate overload protection device."},{"question":"Will the 5SY8340-8BB08 fit in a panel designed for a 5SY4310-7CV?","answer":"Both are 3-module-width SENTRON MCBs on the same DIN-rail footprint, so the mechanical fit is identical. The key difference is the 5SY8340-8BB08 is a D-curve magnetic-only breaker with 25 kA breaking capacity, while the 5SY4310-7CV is a different rating/curve — verify the trip characteristic and interrupting rating match your circuit requirements before substituting."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY8340-8BB08","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/5SY8340-8BB08 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}}