{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY4120-8","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY4120-8","canonicalUrl":"https://aoctrl.com/siemens/5SY4120-8","factsUrl":"https://aoctrl.com/api/mcp/products/5SY4120-8","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SY4120-8, miniature circuit breaker, D tripping characteristic, 1-pole, 10 kA per EN 60898, 20 kA per IEC 60947-2, 400 V AC, 60 V DC.","salesMarkdown":"## What it is and what it does The Siemens SENTRON 5SY4120-8 is a 1-pole miniature circuit breaker with a D tripping characteristic, designed for protecting circuits against overcurrent and short circuits in industrial control panels. It occupies a single 18 mm modular width unit on a DIN rail, with a quick assembly system for snap-on mounting in any position. The D curve means it tolerates high inrush currents — typically used for motor loads, transformers, or capacitive loads where the start-up surge would trip a B or C curve breaker. ## Breaking capacity and standards Rated breaking capacity is 10 kA per EN 60898-1 and 20 kA per IEC 60947-2 at 400 V AC. For DC circuits, it interrupts 15 kA at 60 V per IEC 60947-2. Under UL 1077 and CSA C22.2 No.235, the rating is 5 kA. These figures tell you the maximum fault current the breaker can safely clear — the 20 kA IEC rating gives headroom for high-fault installations where the prospective short-circuit current exceeds 10 kA. Overvoltage category III and pollution degree 3 suit it for fixed industrial installations, not just residential panels. ## Environmental and mounting Rated for ambient temperatures from -40 °C to 75 °C, with humidity derating above 55 °C. IP20 with connected conductors — fine for enclosed panels, not for wet washdown areas. Halogen-free and silicon-free construction matters for sensitive environments like semiconductor fabs or clean rooms where outgassing contaminates processes. Vibration resistance per IEC 60068-2-6: ±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz — survives the shake of a conveyor line or compressor skid. Combined terminals top and bottom accept supply from either direction.","metaTitle":"Siemens 5SY4120-8 SENTRON MCB, D Curve, 1 Pole, 10 kA","metaDescription":"Siemens SENTRON 5SY4120-8 miniature circuit breaker, D tripping characteristic, 1-pole, 10 kA per EN 60898, 20 kA per IEC 60947-2. Active production. Sourced to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["1-Pole MCB (DIN Rail)"],"specifications":{"Depth":"76 mm","Width":"18 mm","title":"5SY4120-8","Height":"90 mm","Maximum":"75 °C","Minimum":"-40 °C","Sealable":"Yes","Standard":"IEC / EN 60898-1, IEC / EN 60947-2 / UL1077","description":"Miniature circuit breaker 230/400 V 10kA, 1-pole, D, 20 A, D=70 mm","Halogen-Free":"Yes","Silicon-Free":"Yes","Design Of Pole":"1P","Number Of Poles":"1","lifecycle_stage":"current","Fastening Method":"Quick assembly system","Mounting Position":"any","at AC rated value":"400 V","at DC rated value":"60 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","Combined Terminal Bottom":"Yes","Suitability For Operation":"Mechanical engineering / industry","Neutral Conductor Switching":"No","Number Of Modular Width Units":"1","Position Of Power Supply Cord":"Any","Tripping Characteristic Class":"D","according to EN 60898 rated value":"10 kA","according to IEC 60947-2 rated value":"20 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","at DC according to IEC 60947-2 rated value":"15 kA","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","supply voltage with single-phase operation at AC rated value":"230 V","power loss [W] for rated value of the current at AC in hot operating state per pole":"1.6 W"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$17.78","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/511f189cfc2e406f244330c3691663a9.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=518164&mlfb=5SY4120-8"},"ai":{"faq":[{"question":"Where can I buy 5SY4120-8?","answer":"This part is sourced and quoted to order against an RFQ through independent distribution channels. Availability and current pricing are confirmed at quote time — submit an RFQ for a firm commitment."},{"question":"What standards does 5SY4120-8 comply with?","answer":"It complies with IEC / EN 60898-1, IEC / EN 60947-2, and UL 1077 / CSA C22.2 No.235. This covers both IEC and North American installations, with breaking capacities of 10 kA (EN), 20 kA (IEC), and 5 kA (UL/CSA)."},{"question":"What is the D tripping characteristic used for?","answer":"The D curve (10–20× In) is designed for circuits with high inrush currents — motor starters, transformers, welding equipment, and capacitive loads. It avoids nuisance tripping on start-up surges that would trip a B or C curve breaker."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY4120-8","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/5SY4120-8 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}}