{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RU7126-4NB0","brand":"Siemens","brandSlug":"siemens","productSlug":"3RU7126-4NB0","canonicalUrl":"https://aoctrl.com/siemens/3RU7126-4NB0","factsUrl":"https://aoctrl.com/api/mcp/products/3RU7126-4NB0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS thermal overload relay, 3RU7126-4NB0, S0 size, 28 A rated operational current, Class 10 trip, screw-type terminals, contactor mounting.","salesMarkdown":"It mounts directly onto a matching S0 contactor — no separate DIN-rail bracket needed — saving panel space and wiring time. The 9.6 W typical power loss at rated current means the heat stays manageable inside a closed enclosure, but keep the 6 mm side spacing to grounded parts for derating headroom. The 28 A rated operational current at 690 V covers most three-phase motor circuits up to about 15 kW at 400 V. Class 10 trip means it opens within 10 seconds at 7.2× set current — fast enough for standard induction motor starts but not for high-inertia loads that need a Class 20 or 30 relay. The thermal bimetal design responds to motor heating, not instantaneous spikes, so nuisance tripping on inrush is unlikely. The relay fastens directly to the contactor — no separate mounting base. The 45 mm width and 96 mm depth keep the assembly within a standard 45 mm contactor footprint. Screw-type terminals on both main and auxiliary circuits accept 2× (0.5…1.5 mm²) solid or stranded, or 2× (0.75…2.5 mm²). Terminal torque: 2…2.5 N·m for main contacts, 0.8…1.2 N·m for auxiliaries.","metaTitle":"Siemens 3RU7126-4NB0 SIRIUS Thermal Overload Relay, 28 A, Cl","metaDescription":"Siemens 3RU7126-4NB0 SIRIUS thermal overload relay, 28 A rated current, Class 10 trip, S0 size, contactor-mount. Active production. Quoted to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Overload Relays"],"specifications":{"Depth":"96 mm","Width":"45 mm","Height":"97 mm","at 24 V":"3 A","Per Pole":"3.2 W","at 230 V":"2 A","Trip Class":"CLASS 10","On The Front":"IP20","Of The Terminal":"IP20","lifecycle_stage":"current","During Operation":"-20 ... +55 °C","During Transport":"-25 ... +70 °C","Fastening Method":"Contactor mounting","Mounting Position":"with vertical mounting surface +/-135° rotatable, with vertical mounting surface +/- 45° tiltable to the front and back","Solid Or Stranded":"2x (0.5 ... 1.5 mm²), 2x (0.75 ... 2.5 mm²)","Product Brand Name":"SIRIUS","Product Designation":"Thermal overload relay","Size Of Overload Relay":"S0","For Main Current Circuit":"screw-type terminals","power loss [W] total typical":"9.6 W","Operating Voltage Rated Value":"690 V","Design Of The Overload Release":"thermal","Operating Frequency Rated Value":"50 ... 60 Hz","Operational Current Rated Value":"28 A","For Auxiliary And Control Circuit":"screw-type terminals","Relative Humidity During Operation":"0 ... 90 %","Surge Voltage Resistance Rated Value":"6 kV","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","Type Of Voltage For Main Current Circuit":"AC/DC","For Main Contacts With Screw-Type Terminals":"2 ... 2.5 N·m","shock resistance according to IEC 60068-2-27":"8g / 11 ms","Required Spacing For Grounded Parts At The Side":"6 mm","For Auxiliary Contacts With Screw-Type Terminals":"0.8 ... 1.2 N·m","Size Of Contactor Can Be Combined Company-Specific":"S0","Installation Altitude At Height Above Sea Level Maximum":"2 000 m","operational current of auxiliary contacts at DC-13 at 24 V":"1 A","Arrangement Of Electrical Connectors For Main Current Circuit":"Top and bottom","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":"23 ... 28 A","Design Of The Fuse Link For Short-Circuit Protection Of The Auxiliary Switch Required":"fuse gL/gG: 6 A, quick: 10 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/4e80d22a37804e1d41176218898580d1.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=1534250&mlfb=3RU7126-4NB0","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RU7126-4NB0/alternatives.json"},"ai":{"faq":[{"question":"What is the closest functional second-source for 3RU7126-4NB0?","answer":"The 3RU7126-4NB0 is a Siemens SIRIUS S0 thermal overload relay. The closest functional peer is the 3RT1016-1BB42 contactor it mounts to — they share the S0 frame and screw-terminal pattern. For a direct drop-in replacement, stick with the same 3RU7 series in the S0 size."},{"question":"Will 3RU7126-4NB0 drop into a panel specified around 3RT1016-1BB42?","answer":"Yes — the 3RU7126-4NB0 is designed for contactor mounting onto S0-size contactors like the 3RT1016 series. No rewiring of the main circuit is needed if the contactor terminals match the screw-type pattern."},{"question":"How do I get current pricing and availability for 3RU7126-4NB0?","answer":"Submit an RFQ through this listing. Pricing and stock are confirmed at quote time through independent distribution channels."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RU7126-4NB0","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/3RU7126-4NB0 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-09-02T08:15:54.622Z","lastPublished":"2026-09-02T08:15:54.622Z","indexable":true}}