{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RU6126-4FB0","brand":"Siemens","brandSlug":"siemens","productSlug":"3RU6126-4FB0","canonicalUrl":"https://aoctrl.com/siemens/3RU6126-4FB0","factsUrl":"https://aoctrl.com/api/mcp/products/3RU6126-4FB0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RU6126-4FB0 thermal overload relay, 34-40 A, Class 10, size S0, screw-type terminals, for contactor mounting.","salesMarkdown":"The Siemens SIRIUS 3RU6126-4FB0 is a thermal overload relay sized for motor protection, with an adjustable current response range of 34 to 40 A. It is designed for direct mounting onto size S0 contactors, forming a compact motor starter combination for panel builds. This is the figure that governs whether the relay coordinates with your motor's acceleration time. Rated operational current is 40 A, operating voltage up to 690 V at 50/60 Hz, with a total typical power loss of 7.5 W (9.6 W at rated current in hot operating state). Mounts directly onto the contactor via the fastening method (contactor mounting), no DIN rail needed for the relay itself — it clips onto the contactor and the assembly snaps onto the DIN rail. The S0 contactor size is the pairing constraint: this relay mates with S0-frame contactors like the 3RT1023 series. Side spacing to grounded parts requires 6 mm clearance. Main contacts accept 2×(0.5…1.5 mm²) solid/stranded or 2×(0.75…2.5 mm²), with AWG equivalents 2×(16…12) and 2×(14…8). Tightening torque is 2 to 2.5 N·m. Auxiliary contacts use smaller gauge: 2×(20…16) and 2×(18…14) AWG. Relative humidity during operation is 0 to 90 %. Shock resistance is 8g / 11 ms per IEC 60068-2-27. Maximum installation altitude is 2000 m above sea level.","metaTitle":"Siemens 3RU6126-4FB0 SIRIUS Overload Relay, 34-40 A, Class 1","metaDescription":"Siemens SIRIUS 3RU6126-4FB0 thermal overload relay, 34-40 A adjustable, Class 10, size S0, screw terminals. Current production. Sourced to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Overload Relays"],"specifications":{"Depth":"85 mm","Width":"45 mm","title":"3RU6126-4FB0","Height":"85 mm","at 24 V":"2 A","Per Pole":"3.2 W","at 110 V":"0.22 A","at 230 V":"2 A","Trip Class":"CLASS 10","description":"Overload relay 34...40 A size S0, class 10, for motor protection for mounting onto contactors main circuit: screw terminal AUX. circuit: screw terminal manual automatic reset","lifecycle_stage":"current","During Operation":"-40 ... +70 °C","During Transport":"-55 ... +80 °C","Fastening Method":"Contactor mounting","Mounting Position":"any","Solid Or Stranded":"2x (0.5 ... 1.5 mm²), 2x (0.75 ... 2.5 mm²)","Product Brand Name":"SIRIUS","Product Designation":"Thermal overload relay","For Main Current Circuit":"screw-type terminals","power loss [W] total typical":"7.5 W","Operating Voltage Rated Value":"690 V","Substance Prohibitance (Date)":"05/01/2012","Design Of The Overload Release":"thermal","Operating Frequency Rated Value":"50 ... 60 Hz","Operational Current Rated Value":"40 A","for AWG cables for main contacts":"2x (16 ... 12), 2x (14 ... 8)","For Auxiliary And Control Circuit":"screw-type terminals","Relative Humidity During Operation":"0 ... 90 %","Surge Voltage Resistance Rated Value":"6 kV","for AWG cables for auxiliary contacts":"2x (20 ... 16), 2x (18 ... 14)","Finely Stranded With Core End Processing":"2x (0.5 ... 1.5 mm²), 2x (0.75 ... 2.5 mm²)","Number Of Poles For Main Current Circuit":"3","shock resistance according to IEC 60068-2-27":"8g / 11 ms","Required Spacing For Grounded Parts At The Side":"6 mm","Size Of Contactor Can Be Combined Company-Specific":"S0","Installation Altitude At Height Above Sea Level Maximum":"2 000 m","Arrangement Of Electrical Connectors For Main Current Circuit":"Top and bottom","Tightening Torque For Main Contacts With Screw-Type Terminals":"2 ... 2.5 N·m","insulation voltage with degree of pollution 3 at AC rated value":"690 V","power loss [W] for rated value of the current at AC in hot operating state":"9.6 W","Adjustable Current Response Value Current Of The Current-Dependent Overload Release":"34 ... 40 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/4ce305b9d6f72557599901cfc8b4bbdb.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=621549&mlfb=3RU6126-4FB0"},"ai":{"faq":[{"question":"What is the adjustable current range of this overload relay?","answer":"The adjustable current response value is 34 to 40 A, set via the dial on the front face."},{"question":"What contactor size does this relay mount onto?","answer":"It is designed for size S0 contactors (company-specific combination size S0), such as the 3RT1023 series. It clips directly onto the contactor."},{"question":"What compliance documentation is available for this part?","answer":"The part is RoHS compliant with a substance prohibition date of 05/01/2012. It also carries a surge voltage resistance of 6 kV and insulation voltage of 690 V at pollution degree 3."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RU6126-4FB0","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/3RU6126-4FB0 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}}