{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RU2126-1EC0","brand":"Siemens","brandSlug":"siemens","productSlug":"3RU2126-1EC0","canonicalUrl":"https://aoctrl.com/siemens/3RU2126-1EC0","factsUrl":"https://aoctrl.com/api/mcp/products/3RU2126-1EC0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS thermal overload relay, 3RU2126-1EC0, CLASS 10, S0 frame, spring-loaded terminals, 45 mm width.","salesMarkdown":"The Siemens 3RU2126-1EC0 is a SIRIUS thermal overload relay — a CLASS 10 device meaning it trips within 10 seconds at 7.2× the set current, fast enough to protect standard induction motors from locked-rotor heating without nuisance tripping on normal start-up. It mounts directly to a contactor (contactor mounting) and uses spring-loaded terminals for the main circuit, so no screwdriver needed for the power connections — just strip and push. The AC-3e maximum operating voltage is 690 V. Power ratings at various voltages tell you the motor size it can protect: 1.5 kW at 400 V, 2.2 kW at 500 V, 3 kW at 690 V. That's a 2 to 4 HP range in practice — sized for small pumps, fans, conveyors. Auxiliary contact ratings span 24 V (2 A) through 400 V (1 A) — enough to switch a PLC input or a contactor coil directly. The integrated auxiliary switch means no add-on block for the basic trip-signal feedback. Temperature compensation is active from -40 to +60 °C, so the trip curve stays accurate in unheated enclosures or near hot ductwork. No official successor has been issued because none is needed — the 3RU2126-1EC0 is the active variant for its rating window. If you see a date-code mismatch between this and another S0 relay in the same panel, verify only that the trip current range matches; the mounting and wiring are identical across the S0 family. ## Installation and wiring notes The auxiliary contact is integrated, so no separate block to order for the basic trip-indication circuit. For message 'Tripped' — that's the contact state when the relay has operated; wire it to the PLC or HMI input for fault annunciation. Power dissipation per pole is 1.9 W. In a dense panel with multiple S0 relays side by side, account for that heat in the enclosure thermal budget — not a concern for a single unit, but relevant in a multi-motor group.","metaTitle":"Siemens 3RU2126-1EC0 SIRIUS thermal overload relay, CLASS 10","metaDescription":"Siemens SIRIUS 3RU2126-1EC0 thermal overload relay, CLASS 10, S0 frame, spring-loaded terminals. Current production. Quoted to order.","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":"1.9 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","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":"1.5 kW","at 480 V rated value":"4 A","at 500 V rated value":"2.2 kW","at 600 V rated value":"4 A","at 690 V rated value":"3 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 y","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":"4 A","at AWG cables for main contacts":"1x (18 ... 8)","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":"4 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":"5.7 W","Adjustable Current Response Value Current Of The Current-Dependent Overload Release":"2.8 ... 4 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/449ac4cc067dce04ec2190380d536a08.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=364998&mlfb=3RU2126-1EC0","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RU2126-1EC0/alternatives.json"},"ai":{"faq":[{"question":"What does the note 'for message Tripped' mean?","answer":"It describes the auxiliary contact state when the overload relay has operated. Wire that contact to a PLC input or indicator lamp to signal a tripped condition."},{"question":"What is the depth of the 3RU2126-1EC0?","answer":"84 mm. Width is 45 mm, height is 102 mm — S0 frame size."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RU2126-1EC0","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/3RU2126-1EC0 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}}