{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RU2126-4FC0","brand":"Siemens","brandSlug":"siemens","productSlug":"3RU2126-4FC0","canonicalUrl":"https://aoctrl.com/siemens/3RU2126-4FC0","factsUrl":"https://aoctrl.com/api/mcp/products/3RU2126-4FC0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RU2126-4FC0 thermal overload relay, CLASS 10, S0 size, 690 V rated, contactor-mount, spring-loaded terminals.","salesMarkdown":"S0 frame size, so it mates directly with the S0 contactor range via the contactor-mount fastening method — no separate base or wiring between them. Rated 690 V, with power ratings at 400 V (18.5 kW), 500 V (22 kW), and 690 V (37 kW) in AC-3e duty. The auxiliary switch is integrated — one less add-on to spec. Spring-loaded terminals on the main circuit, accepting 2× (0.5 to 2.5 mm²) solid or stranded. Temperature compensation active from -40 to +60 °C, so it doesn't drift when the panel warms up next to the drive. CLASS 10 is the key selection parameter here. If your motor starts against a high-inertia load that takes longer than 10 seconds to accelerate, you need CLASS 20 or 30 — this relay will nuisance-trip. For a standard pump, fan, or conveyor motor starting unloaded, CLASS 10 is the right call. The 690 V rated value covers 400 V, 480 V, 600 V, and 690 V systems; just watch that the 480 V and 600 V entries show 40 A rather than a kW figure, so you're sizing by motor FLA at those voltages. The note 'for message Tripped' on the line item is a Siemens catalog flag — it means this variant includes the remote trip-indication contact (the auxiliary switch) wired to signal a tripped state back to the PLC or annunciator. Not all 3RU2 variants carry that; if your panel needs a hardwired 'motor tripped' feedback, this is the one. ## Integration notes Mounts directly onto the S0 contactor — no DIN rail needed for the relay itself, though the contactor likely sits on one. Any mounting position allowed. Depth 84 mm, width 45 mm, height 102 mm — fits standard 45 mm-wide contactor footprint. Screwdriver shaft diameter 3 mm, tip 3.0 × 0.5 mm for the spring-loaded terminals. Operating frequency 50 to 60 Hz, so it's fine on either 50 Hz or 60 Hz supply. MTTF at high demand rate 2,280 years — that's a reliability number for safety-related applications, not a warranty. Substance prohibitance date 10/01/2009 aligns with RoHS compliance scope.","metaTitle":"Siemens 3RU2126-4FC0 SIRIUS Thermal Overload Relay, CLASS 10","metaDescription":"Siemens 3RU2126-4FC0 SIRIUS thermal overload relay, CLASS 10 trip, S0 frame, 690 V rated, contactor-mount. Current production. Sourced 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":"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","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":"18.5 kW","at 480 V rated value":"40 A","at 500 V rated value":"22 kW","at 600 V rated value":"40 A","at 690 V rated value":"37 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":"40 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":"40 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":"34 ... 40 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/c70e8f8ffe84999e8ef47892fa422234.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=279440&mlfb=3RU2126-4FC0","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RU2126-4FC0/alternatives.json"},"ai":{"faq":[{"question":"What does the note 'for message Tripped' mean?","answer":"It means this variant includes the integrated auxiliary switch that signals a tripped condition — a hardwired feedback contact for the PLC or alarm panel."},{"question":"Does this relay have RoHS or REACH compliance documentation?","answer":"The substance prohibitance date of 10/01/2009 indicates RoHS compliance scope. Standard Siemens SIRIUS documentation package includes CE, UL, CSA, and RoHS declarations."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RU2126-4FC0","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/3RU2126-4FC0 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}}