{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RU2126-4NC0","brand":"Siemens","brandSlug":"siemens","productSlug":"3RU2126-4NC0","canonicalUrl":"https://aoctrl.com/siemens/3RU2126-4NC0","factsUrl":"https://aoctrl.com/api/mcp/products/3RU2126-4NC0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RU2126-4NC0 thermal overload relay, CLASS 10, Size S0, contactor mounting, spring-loaded terminals, 690 V rated value.","salesMarkdown":"The Siemens 3RU2126-4NC0 is a SIRIUS-brand thermal overload relay, Size S0, designed for contactor mounting. The relay is rated for a maximum operating voltage of 690 V. Its current-carrying capacity is voltage-dependent: it handles 3 A at 120 V, 2 A at 24 V and 230 V, 1 A at 400 V, and 0.75 A at 690 V — these are the auxiliary contact ratings, not the motor full-load current range. For motor protection, the relay carries power ratings of 15 kW at 400 V, 18.5 kW at 500 V, and 22 kW at 690 V, with corresponding FLA ratings of 28 A at both 480 V and 600 V. The main circuit uses spring-loaded terminals, accepting 2× (0.5 to 2.5 mm²) solid or stranded wire. Temperature compensation is active from -40 to +60 °C, keeping the trip curve stable across the panel's ambient range. For compliance documentation, the relay carries a substance prohibition date of October 1, 2009, which aligns with the original EU RoHS directive. The MTTF under high demand rate is listed at 2,280 years, reflecting the solid-state reliability of the thermal bimetal mechanism in low-cycle applications. The relay mounts directly onto the corresponding SIRIUS contactor (S0 frame) — no DIN rail required, no additional brackets. Fastening method is contactor mounting, meaning it clips onto the contactor's front face and connects via the integrated auxiliary switch. Dimensions: 45 mm wide, 102 mm high, 84 mm deep — the S0 footprint is compact enough for dense control panels. The auxiliary switch is integrated into the relay body, so there's no separate add-on block needed for the trip/alarm signal. The note \"for message 'Tripped'\" on the relay indicates that the integrated auxiliary contact changes state when the relay trips, providing a remote indication to a PLC or annunciator. Screwdriver shaft diameter is 3 mm, tip size 3.0 × 0.5 mm — a standard PZ1 or similar will fit the spring-loaded terminal cages.","metaTitle":"Siemens 3RU2126-4NC0 SIRIUS Thermal Overload Relay, CLASS 10","metaDescription":"Siemens 3RU2126-4NC0 SIRIUS thermal overload relay, CLASS 10 trip, S0 size, contactor mount, spring terminals. Current production. Sourced to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Overload Relays"],"specifications":{"Note":"for message \"Tripped\"","Depth":"84 mm","Width":"45 mm","Height":"102 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":"Contactor mounting","Mounting Position":"any","Solid Or Stranded":"2x (0.5 ... 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":"spring-loaded terminals","Temperature Compensation":"-40 ... +60 °C","MTTF with high demand rate":"2 280 a","Design Of Screwdriver Shaft":"Diameter 3 mm","Size Of The Screwdriver Tip":"3,0 x 0,5 mm","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","For Auxiliary And Control Circuit":"spring-loaded 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 ... 14)","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","Finely Stranded Without Core End Processing":"2x (0.5 ... 1.5 mm²)","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","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/494c0b711f2727d4e3ca9d326b267a60.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=237127&mlfb=3RU2126-4NC0","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RU2126-4NC0/alternatives.json"},"ai":{"faq":[{"question":"What does the note 'for message Tripped' mean on this relay?","answer":"It means the integrated auxiliary switch is wired to signal a trip condition — typically a normally-open contact that closes when the bimetal releases, sending a 'tripped' status back to a PLC or HMI."},{"question":"What are the physical dimensions of the 3RU2126-4NC0?","answer":"Width 45 mm, height 102 mm, depth 84 mm. It is a Size S0 form factor designed for direct contactor mounting."},{"question":"Will the 3RU2126-4NC0 fit into a panel designed for a 3RT2027-2AP00-ZX95 contactor?","answer":"Yes — the 3RU2126-4NC0 is a Size S0 thermal overload relay specifically designed to mount onto SIRIUS S0 contactors, which includes the 3RT2027 and 3RT2028 frames. It clips directly onto the contactor without rewiring the main circuit."},{"question":"What compliance documentation does this relay carry?","answer":"The relay has a substance prohibition date of October 1, 2009, confirming RoHS compliance from that date. Standard SIRIUS documentation includes CE and UL/CSA certifications per the manufacturer's declaration."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RU2126-4NC0","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/3RU2126-4NC0 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}}