{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY4303-8","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY4303-8","canonicalUrl":"https://aoctrl.com/siemens/5SY4303-8","factsUrl":"https://aoctrl.com/api/mcp/products/5SY4303-8","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SY4303-8 miniature circuit breaker, 3-pole, 3 A rated current, D tripping characteristic, 10 kA breaking capacity per EN 60898, 35 kA per IEC 60947-2, 3 modular width units (54 mm), IP20, sealable.","salesMarkdown":"## 3 A D-Curve MCB for High-Inrush Three-Phase Loads The Siemens 5SY4303-8 is a 3-pole miniature circuit breaker from the SENTRON series, rated 3 A at AC with a D tripping characteristic. The D curve means it tolerates short-duration inrush currents 10–20 times the rated current — the right choice for motor starters, transformers, or solenoid banks where the startup surge would nuisance-trip a B or C curve breaker. Breaking capacity is 10 kA per EN 60898 for general distribution, 35 kA per IEC 60947-2 for industrial panel duty, 15 kA at DC per IEC 60947-2, and 5 kA per UL 1077 / CSA C22.2 No.235. The 35 kA figure is the one that matters for high-fault-current industrial switchboards — it clears a bolted fault without cascading upstream. ## Panel Fit and Temperature Derating Width is 54 mm (3 modular units on a DIN rail), depth 76 mm, height 90 mm. The quick-assembly fastening method snaps onto the rail without tools; mounting position is any orientation. Installation depth of 70 mm means it sits flush in a standard 80 mm deep enclosure with room for wiring behind. Rated current derates with ambient temperature: 3 A at 35 °C, 2.78 A at 45 °C, 2.71 A at 50 °C, 2.62 A at 55 °C, 2.54 A at 60 °C. If the panel ambient runs above 35 °C, the load current must be reduced accordingly — a common oversight in sealed enclosures with multiple breakers ganged together. ## Active Production — Sourced to Order Sourced through independent distribution against an RFQ. For a project milestone, submit the BOM quantity and target delivery date — the supply channel can lock in the allocation to protect the commissioning window.","metaTitle":"Siemens 5SY4303-8 SENTRON MCB, 3-Pole, 3 A, D Curve","metaDescription":"Siemens 5SY4303-8 SENTRON 3-pole MCB, 3 A rated, D tripping characteristic. Breaking capacity 10 kA (EN 60898) / 35 kA (IEC 60947-2).","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":"5SY4303-8","Height":"90 mm","Maximum":"75 °C","Minimum":"-40 °C","Sealable":"Yes","description":"Miniature circuit breaker 400 V 10kA, 3-pole, D, 3 A, D=70 mm","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","acc. to IEC 81346-2":"F","at AC / rated value":"3 A","protection class IP":"IP20, with connected conductors","Overvoltage Category":"III","Combined Terminal Top":"Yes","acc. to DIN EN 61346-2":"F","at 35 °C / rated value":"3 A","at 45 °C / rated value":"2.78 A","at 50 °C / rated value":"2.71 A","at 55 °C / rated value":"2.62 A","at 60 °C / rated value":"2.54 A","Combined Terminal Bottom":"Yes","Suitability For Operation":"Mechanical engineering / industry","Number Of Modular Width Units":"3","Tripping Characteristic Class":"D","acc. to EN 60898 / rated value":"10 kA","Position / Of Power Supply Cord":"Any","acc. to IEC 60947-2 / rated value":"35 kA","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 DC / acc. to IEC 60947-2 / rated value":"15 kA","Type Of Voltage / Of The Operating Voltage":"AC","at AC / acc. to UL 1077 and CSA C22.2 No.235":"5 kA","vibration resistance / acc. to IEC 60068-2-6":"±1mm at 5 to 25Hz; 50m/s² at 25 to 150Hz","Product Component / Neutral Conductor Switching":"No","with multi-phase operation / at AC / rated value":"440 V","operating voltage / at DC / rated value / maximum":"72 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":"$119.38 – $240.21","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/74f9512332bd6559d99c4effd708f6eb.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=309984&mlfb=5SY4303-8"},"ai":{"faq":[{"question":"Where can I buy the 5SY4303-8 and get a price?","answer":"This part is sourced to order against an RFQ through independent distribution."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY4303-8","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/5SY4303-8 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}}