{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RU2126-4EC0","brand":"Siemens","brandSlug":"siemens","productSlug":"3RU2126-4EC0","canonicalUrl":"https://aoctrl.com/siemens/3RU2126-4EC0","factsUrl":"https://aoctrl.com/api/mcp/products/3RU2126-4EC0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RU2126-4EC0 thermal overload relay, size S0, Class 10 trip class, 690 V rated insulation voltage, spring-loaded terminals, contactor-mount design.","salesMarkdown":"## Trip Class 10 — what it means for motor protection The 3RU2126-4EC0: The thermal bimetallic release tracks the motor's I²t heating curve, not instantaneous overcurrent — it protects against sustained overloads while allowing normal starting transients. ## Mounting and termination — panel-fit constraints Fastens directly to the contactor via the integrated mounting interface — no DIN-rail bracket needed, which saves 45 mm of panel width compared to a rail-mounted block. Mounts in any position, so vertical or horizontal contactor orientation is acceptable — useful when panel layout forces a non-standard contactor angle. ## Auxiliary contact ratings — what the voltage columns tell you At 690 V AC the auxiliary contact is rated 0.75 A — this is the ceiling for signaling in 690 V control circuits common in European industrial installations. The 'for message Tripped' note means the auxiliary contact changes state when the overload trips — it's a normally-closed break contact in series with the contactor coil, not a separate alarm relay. ## Motor power coverage across common voltages Rated motor power at 400 V is 15 kW, at 500 V is 18.5 kW, and at 690 V is 30 kW — the power scales with voltage because the current setting range stays constant. Current ratings at 480 V and 600 V are both 32 A — this is the thermal current setting ceiling; the actual motor FLA must be set within the relay's adjustment range, not at the maximum. ## Environmental and compliance footprint Storage and transport limits are -55 to +80 °C — wide enough for unheated warehouses and container shipping. Substance prohibitance date is 10/01/2009 — this aligns with the original EU RoHS directive; the relay is RoHS-compliant for the European market. MTTF with high demand rate is 2,280 years — this is a calculated figure for the electromechanical mechanism under continuous cycling, not a warranty period. Sourced through authorized distribution channels; volume pricing and lead time confirmed at RFQ against the specific quantity and delivery window.","metaTitle":"Siemens 3RU2126-4EC0 SIRIUS Thermal Overload Relay, Size S0","metaDescription":"Siemens 3RU2126-4EC0 SIRIUS thermal overload relay, size S0, Class 10 trip, 690 V rated, 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","title":"3RU2126-4EC0","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","description":"Overload relay 27...32 A Thermal For motor protection Size S0, Class 10 Contactor mounting Main circuit: Spring-type terminal Auxiliary circuit: spring-type terminal Manual-Automatic-Reset","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":"32 A","at 500 V rated value":"18.5 kW","at 600 V rated value":"32 A","at 690 V rated value":"30 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":"32 A","for 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","for 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":"32 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":"27 ... 32 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$142.44","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/83aa4acdcf7876a1f5cf0820864e1ce7.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=421258&mlfb=3RU2126-4EC0"},"ai":{"faq":[{"question":"What is the trip class and why does it matter?","answer":"This matches the start-up profile of standard AC induction motors — fast enough to protect against locked-rotor conditions but slow enough to allow normal inrush without nuisance trips."},{"question":"Will 3RU2126-4EC0 fit a panel designed for 3RV6021-4DA10?","answer":"The 3RU2126-4EC0 is a contactor-mounted overload relay, while the 3RV6021-4DA10 is a motor-protective circuit breaker with its own mounting footprint. They are not direct drop-in replacements — the 3RU requires a matching SIRIUS contactor as its base, whereas the 3RV is a standalone device with integral disconnect and short-circuit protection."},{"question":"What compliance documentation does Siemens provide for this relay?","answer":"The relay carries a substance prohibitance date of 10/01/2009, indicating RoHS compliance. The SIRIUS series typically includes CE, UL, and CSA certifications, though specific approval markings should be verified against the unit's nameplate for the exact variant."},{"question":"How is 3RU2126-4EC0 quoted for volume purchases?","answer":"Quoted to order against the BOM quantity through independent distribution."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RU2126-4EC0","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/3RU2126-4EC0 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-08-11T15:51:03.652Z","lastPublished":"2026-08-11T15:51:03.652Z","indexable":true}}