{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY7303-8MA","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY7303-8MA","canonicalUrl":"https://aoctrl.com/siemens/5SY7303-8MA","factsUrl":"https://aoctrl.com/api/mcp/products/5SY7303-8MA","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SY7303-8MA miniature circuit breaker, 3 A, D tripping characteristic, 30 kA at 400 V AC, 3-pole, magnetic-only operation.","salesMarkdown":"## What this 3 A D-curve MCB does in a panel That D-curve means it tolerates the high inrush of motor-starting or transformer loads — the magnetic trip holds off until roughly 10–14 times rated current, so you don't get nuisance trips on a compressor or conveyor start. It's magnetic-only — no thermal bimetal — so it's sized for applications where overload protection is handled upstream or by the load itself, and the breaker is there strictly for short-circuit isolation. ## Mounting and wiring in a dusty enclosure The screw terminals accept solid or stranded copper from 0.75 mm² up to 35 mm², torqued to 2.5–3.5 N·m. Both top and bottom have combined terminals (busbar and conductor in the same clamp), which keeps the wiring tidy when you're feeding a common bus. IP20 with connected conductors — fine inside a sealed enclosure, but not for open-panel washdown areas. The sealable cover (padlockable) lets you lock out the handle for LOTO compliance. ## Environmental tolerance for the hot, humid control room That covers the inside of a cement plant or brewery control cabinet that sees 50 °C in summer and condensation cycles. Humidity tolerance is rated: max 95% RH at 55 °C, derating to 55% at 70 °C and 35% at 75 °C.","metaTitle":"Siemens 5SY7303-8MA SENTRON MCB, 3A D-curve, 30kA, 3-pole","metaDescription":"Siemens 5SY7303-8MA SENTRON miniature circuit breaker, 3 A, D tripping characteristic, 30 kA at 400 V AC, 3-pole, magnetic-only. Active production. Sourced 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","Solid":"0.75 ... 35 mm²","Width":"54 mm","title":"5SY7303-8MA","Height":"90 mm","Sealable":"Yes","Stranded":"0.75 ... 35 mm²","Rated Value":"50/60 Hz","description":"Miniature circuit breakers 400v Icu 30kA 3-pole, 3 A, only magnetic","Halogen-Free":"Yes","Silicon-Free":"Yes","Mounting type":"Quick assembly system","During Storage":"-40 ... +75 °C","Number of poles":"3","Type of voltage":"AC","lifecycle_stage":"current","Mounting position":"any","Installation depth":"70 mm","Product brand name":"SENTRON","Ambient temperature":"-35 ... +70 °C","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","Design of the product":"Only magnetic tripping operation","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":"5SY7MA","Suitability for operation":"Industry","Current / at AC / rated value":"3 A","Tripping characteristic class":"D","at DC / rated value / maximum":"72 V","Position / of power supply cord":"Any","acc. to IEC 60947-2 / rated value":"30 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","Tightening torque / with screw-type terminals":"2.5 ... 3.5 N·m","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","Tightening torque [lbf·in] / with screw-type terminals":"22 ... 31 lbf·in"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/346e59c7f3d2d214f11ec07620f14417.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=696506&mlfb=5SY7303-8MA"},"ai":{"faq":[{"question":"What is the breaking capacity of the 5SY7303-8MA?","answer":"Rated 30 kA at 400 V AC per IEC 60947-2, which is the standard for industrial MCBs in high-fault-current panels."},{"question":"Will the 5SY7303-8MA drop into a panel wired for a 5SY6602-8?","answer":"Both are 3-pole SENTRON MCBs on the same DIN-rail footprint, so the mechanical fit is identical. The key difference is the tripping characteristic: the 5SY7303-8MA is D-curve (magnetic-only), while the 5SY6602-8 is a different characteristic — verify the upstream selectivity and load inrush before swapping without re-coordination."},{"question":"Where can I buy the 5SY7303-8MA?","answer":"Sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time."},{"question":"What compliance documentation does Siemens provide for the 5SY7303-8MA?","answer":"The product carries IEC 60947-2 certification (30 kA rating) and is designed for industrial use. Halogen-free and silicon-free materials are confirmed. For RoHS, REACH, and UL declarations, request the manufacturer's compliance pack at quote time — these are typically provided with the shipment documentation."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY7303-8MA","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/5SY7303-8MA 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}}