{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RU2126-1DC0","brand":"Siemens","brandSlug":"siemens","productSlug":"3RU2126-1DC0","canonicalUrl":"https://aoctrl.com/siemens/3RU2126-1DC0","factsUrl":"https://aoctrl.com/api/mcp/products/3RU2126-1DC0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS thermal overload relay, Size S0, Trip Class 10, 3RU2126-1DC0, contactor-mount, spring-loaded terminals, 84 mm depth.","salesMarkdown":"## SIRIUS thermal overload relay, Size S0 — 3RU2126-1DC0 The Siemens 3RU2126-1DC0 is a SIRIUS thermal overload relay in Size S0 with Trip Class 10. It mounts directly to a contactor and uses spring-loaded terminals for the main circuit wiring. Rated for AC-3e switching up to 690 V and 50/60 Hz, this relay handles motor loads in the 1.1 kW to 2.2 kW range depending on line voltage. The thermal bimetallic release compensates for ambient temperature shifts from -40 °C to +60 °C, so the protection curve stays accurate whether the relay is in a heated control room or a cold warehouse. ## Mounting and wiring — panel integration Fastens directly to the contactor (contactor mounting) — no DIN rail required, which saves rail space in a crowded panel. The Size S0 footprint fits alongside SIRIUS contactors of the same frame size. Spring-loaded terminals accept 2× (0.5 to 2.5 mm²) solid or stranded wire; a 3 mm diameter screwdriver tip is specified for the terminal screws. Mounting position is any orientation, so vertical or horizontal busbars are both fine. Depth of 84 mm, width 45 mm, height 102 mm — compact enough for shallow enclosures. The integrated auxiliary switch provides a normally closed contact for the \"Tripped\" message, which can be wired into a PLC input or a motor control center alarm circuit. Trip Class 10 means the relay coordinates with standard motor starters and contactors like the 3RT2 series. The thermal release is self-powered — no external control voltage needed for the overload function. Power dissipation per pole is 1.9 W, which matters for thermal management in a multi-starter group. Auxiliary contact ratings are given for several control voltages: 2 A at 24 V, 3 A at 120 V, 2 A at 230 V, 1 A at 400 V.","metaTitle":"Siemens 3RU2126-1DC0 SIRIUS Thermal Overload Relay, Size S0,","metaDescription":"Siemens 3RU2126-1DC0 SIRIUS thermal overload relay, Size S0, Trip Class 10, contactor-mount, spring-loaded terminals. Active 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":"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":"1.1 kW","at 480 V rated value":"3.2 A","at 500 V rated value":"1.5 kW","at 600 V rated value":"3.2 A","at 690 V rated value":"2.2 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":"3.2 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":"3.2 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":"2.2 ... 3.2 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$30.48","priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/35e99096cdcb5a0e575d4dbf071eac3a.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=407033&mlfb=3RU2126-1DC0","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RU2126-1DC0/alternatives.json"},"ai":{"faq":[{"question":"What is the closest functional second-source to 3RU2126-1DC0?","answer":"The 3RU2116-1FC1 is a functionally similar SIRIUS thermal overload relay in the same Size S0 frame, but it covers a different current range. The 3RU2126-1DC0 will not drop into a panel wired for the 3RU2116-1FC1 without checking the current setting range and verifying the contactor interface — the mounting and terminal layout are the same, but the overload pickup values differ."},{"question":"What does the 'Note for message Tripped' mean on this relay?","answer":"It refers to the integrated auxiliary switch that changes state when the thermal overload relay trips. That contact can be wired to a PLC input or an alarm lamp to signal a motor overload condition — it's the electrical indication that the relay has operated."},{"question":"What is the depth of 3RU2126-1DC0?","answer":"The depth is 84 mm. With a width of 45 mm and height of 102 mm, it fits standard shallow enclosures and leaves room for wiring behind the relay."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RU2126-1DC0","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/3RU2126-1DC0 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}}