{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RU2126-4NB1","brand":"Siemens","brandSlug":"siemens","productSlug":"3RU2126-4NB1","canonicalUrl":"https://aoctrl.com/siemens/3RU2126-4NB1","factsUrl":"https://aoctrl.com/api/mcp/products/3RU2126-4NB1","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RU2126-4NB1 thermal overload relay, S0 size, Class 10, 690 V rated, screw terminals.","salesMarkdown":"Siemens 3RU2126-4NB1 is a SIRIUS thermal overload relay, S0 size, Class 10 trip. Rated for 690 V (AC-3e) and carrying motor power ratings of 15 kW at 400 V, 18.5 kW at 500 V, and 22 kW at 690 V, this relay covers a solid band of European and IEC motor loads. The current ratings at 480 V and 600 V are both 28 A, which aligns with typical North American NEMA motor frames in that power band. ## S0 Footprint and Panel Fit Screw terminals accept 2× (0.5...1.5 mm²) or 2× (0.75...2.5 mm²) solid or stranded wire; a Pozidriv PZ 2 bit with 5–6 mm shaft diameter is the field tool. Mountable in any position with stand-alone installation, and temperature-compensated from -40 to +60 °C — so no derating headache for outdoor enclosures or unventilated cabinets near ovens. The Class 10 trip curve is the key selection parameter: it's the standard for general-purpose induction motors (DOL starting, moderate inertia loads). If your motor has a long acceleration time (high-inertia fan or centrifuge), you'd step to Class 20 — but for the vast majority of pump, conveyor, and compressor applications, Class 10 is the right call. The 690 V rated value (AC-3e) covers 400 V three-phase systems with headroom for 480 V and 600 V installations. The MTTF of 2,280 years (high-demand rate) reflects a robust bimetal design with no electronics to fail — the failure mode is mechanical wear on the trip mechanism, not semiconductor drift.","metaTitle":"Siemens 3RU2126-4NB1 SIRIUS Thermal Overload Relay, Class 10","metaDescription":"Siemens 3RU2126-4NB1 SIRIUS thermal overload relay, S0 size, Class 10 trip, 690 V rated. Current lifecycle stage. Sourced to order against RFQ. RoHS compliant per 10/01/2009.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Overload Relays"],"specifications":{"Note":"for message \"Tripped\"","Depth":"95 mm","Width":"45 mm","Height":"97 mm","at 24 V":"2 A","at 60 V":"0.3 A","Per Pole":"3.2 W","at 110 V":"0.22 A","at 120 V":"3 A","at 125 V":"0.22 A","at 220 V":"0.11 A","at 230 V":"2 A","at 400 V":"1 A","at 690 V":"0.75 A","Trip Class":"CLASS 10","Rated Value":"690 V","During Storage":"-55 ... +80 °C","lifecycle_stage":"current","During Operation":"-40 ... +70 °C","During Transport":"-55 ... +80 °C","Fastening Method":"stand-alone installation","For Main Contacts":"M4","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","at 400 V rated value":"15 kW","at 480 V rated value":"28 A","at 500 V rated value":"18.5 kW","at 600 V rated value":"28 A","at 690 V rated value":"22 kW","Size Of Overload Relay":"S0","For Main Current Circuit":"screw-type terminals","Temperature Compensation":"-40 ... +60 °C","MTTF with high demand rate":"2 280 y","Design Of Screwdriver Shaft":"Diameter 5 ... 6 mm","Size Of The Screwdriver Tip":"Pozidriv PZ 2","at AC-3e rated value maximum":"690 V","Substance Prohibitance (Date)":"10/01/2009","Design Of The Auxiliary Switch":"integrated","Design Of The Overload Release":"thermal","Operating Frequency Rated Value":"50 ... 60 Hz","Operational Current Rated Value":"28 A","at AWG cables for main contacts":"2x (16 ... 12), 2x (14 ... 8)","For Auxiliary And Control Circuit":"screw-type terminals","Between Main And Auxiliary Circuit":"440 V","Relative Humidity During Operation":"10 ... 95 %","Display Version For Switching Status":"Slide switch","Surge Voltage Resistance Rated Value":"6 kV","at AWG cables for auxiliary contacts":"2x (20 ... 16), 2x (18 ... 14)","Of The Auxiliary And Control Contacts":"M3","Between Auxiliary And Auxiliary Circuit":"440 V","reference code according to IEC 81346-2":"F","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","For Main Contacts With Screw-Type Terminals":"2 ... 2.5 N·m","number of CO contacts for auxiliary contacts":"0","number of NC contacts for auxiliary contacts":"1","number of NO contacts for auxiliary contacts":"1","shock resistance according to IEC 60068-2-27":"8g / 11 ms","For Auxiliary Contacts With Screw-Type Terminals":"0.8 ... 1.2 N·m","operational current at AC-3e at 400 V rated value":"28 A","Size Of Contactor Can Be Combined Company-Specific":"S0","contact rating of auxiliary contacts according to UL":"B600 / R300","Installation Altitude At Height Above Sea Level Maximum":"2 000 m","Arrangement Of Electrical Connectors For Main Current Circuit":"Top and bottom","For Short-Circuit Protection Of The Auxiliary Switch Required":"fuse gG: 6 A, quick: 10 A","insulation voltage with degree of pollution 3 at AC rated value":"690 V","Product Component Removable Terminal For Auxiliary And Control Circuit":"No","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"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/fb0583ec1de48966edcdfac9bdba4715.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=298790&mlfb=3RU2126-4NB1","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RU2126-4NB1/alternatives.json"},"ai":{"faq":[{"question":"What compliance documentation is available for 3RU2126-4NB1?","answer":"The substance prohibitance date of 10/01/2009 indicates RoHS compliance from that date. The SIRIUS series carries CE, UL, CSA, and IEC certifications per standard Siemens documentation."},{"question":"Will 3RU2126-4NB1 drop into a panel specified around 3RU2116-1FC1?","answer":"Both are S0-size SIRIUS overload relays with the same 45 mm width and screw-terminal pattern, so mechanical fit and wiring are identical. The difference is the current range — verify that 3RU2126-4NB1 covers your motor FLA before swapping."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RU2126-4NB1","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/3RU2126-4NB1 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}}