{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RU2126-4DB1","brand":"Siemens","brandSlug":"siemens","productSlug":"3RU2126-4DB1","canonicalUrl":"https://aoctrl.com/siemens/3RU2126-4DB1","factsUrl":"https://aoctrl.com/api/mcp/products/3RU2126-4DB1","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RU2126-4DB1, thermal overload relay, size S0, Class 10, screw terminals, 11 kW at 400 V, 22 kW at 690 V.","salesMarkdown":"The Siemens SIRIUS 3RU2126-4DB1 is a thermal overload relay — the part that sits between the contactor and the motor, watching current and tripping before the winding cooks. The relay is size S0, the most common frame in the SIRIUS modular system, and it mounts stand-alone or directly onto a matching SIRIUS contactor. At 400 V AC-3e duty it's rated for 11 kW motor output; at 690 V that rises to 22 kW. The current setting range is covered by the 25 A rating at 480 V and 600 V. These are the numbers that decide whether this relay matches your motor nameplate — if your motor FLA sits inside the adjustment range of this unit, it's the right pick. Trip Class 10 is the default for most general-purpose motor starting. If you're starting a high-inertia load (centrifuge, flywheel) that needs a longer acceleration ramp, you'd want Class 20 or 30 — but for conveyors, pumps, compressors, and fans, Class 10 is correct and gives faster protection against a stalled rotor. Dimensions are 45 mm wide, 97 mm tall, 95 mm deep — a compact S0 footprint that fits a standard 45 mm-wide DIN-rail slot. Mounting position is any, which helps when panel space is tight. The main circuit terminals accept screw-type connections: 2× (0.5 to 1.5 mm²) or 2× (0.75 to 2.5 mm²) solid or stranded. Use a PZ2 Pozidriv screwdriver with a 5–6 mm shaft diameter. Temperature compensation is active from -40 to +60 °C, so the trip curve stays accurate in a warm cabinet. The part is RoHS-compliant per the substance prohibition date of October 1, 2009. The MTTF with high demand rate is listed at 2,280 years — a reliability figure that supports holding this as a critical spare without worrying about shelf-life degradation. The note on the product line reads \"for message 'Tripped'\" — this is the signal the integrated auxiliary switch sends when the relay has operated, used to trigger an alarm or stop the contactor.","metaTitle":"Siemens 3RU2126-4DB1 SIRIUS Thermal Overload Relay, Class 10","metaDescription":"Siemens SIRIUS 3RU2126-4DB1 thermal overload relay, size S0, Class 10 trip, 11 kW at 400 V AC-3e. Current-production part sourced to order against an RFQ.","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":"2.7 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":"11 kW","at 480 V rated value":"25 A","at 500 V rated value":"15 kW","at 600 V rated value":"25 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 a","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":"25 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":"25 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":"8.1 W","Adjustable Current Response Value Current Of The Current-Dependent Overload Release":"20 ... 25 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$36.83","priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/05ca871daf3cd6c4050f6a612c9fd428.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=507311&mlfb=3RU2126-4DB1","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RU2126-4DB1/alternatives.json"},"ai":{"faq":[{"question":"What is the trip class and why does it matter?","answer":"It is Class 10, meaning it will trip within 10 seconds at 7.2× the current setting. This is the correct class for standard induction motor starting with pumps, fans, and compressors — fast enough to protect the motor during a stall, but not so fast that it nuisance-trips during a normal start."},{"question":"What is the note \"for message 'Tripped'\" on this part?","answer":"That note refers to the signal from the integrated auxiliary switch. When the overload relay trips, the auxiliary contact changes state — that's the \"message 'Tripped'\" used to trigger an alarm or to break the contactor coil circuit."},{"question":"What are the mounting dimensions?","answer":"The relay is 45 mm wide, 97 mm tall, and 95 mm deep. It mounts in any position and fits a standard 45 mm DIN-rail slot in the panel."},{"question":"What compliance documentation is available?","answer":"The part is RoHS-compliant with a substance prohibition date of October 1, 2009. The MTTF with high demand rate is 2,280 years, supporting its use as a reliable critical spare."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RU2126-4DB1","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/3RU2126-4DB1 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}}