{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RU2126-4BJ0","brand":"Siemens","brandSlug":"siemens","productSlug":"3RU2126-4BJ0","canonicalUrl":"https://aoctrl.com/siemens/3RU2126-4BJ0","factsUrl":"https://aoctrl.com/api/mcp/products/3RU2126-4BJ0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS thermal overload relay, 3RU2126-4BJ0, Class 10, 690 V rated, S0 size, contactor-mount, for motor protection.","salesMarkdown":"Rated for 690 V and 50/60 Hz operation, it covers the common industrial voltage range up to 690 V line-to-line. Mounts directly onto a contactor via the contactor mounting fastening method — no DIN rail needed, saving panel space. Accepts any mounting position. Main circuit connections use ring cable lugs with M4 screws; the auxiliary switch is integrated, no separate block needed. The thermal overload release is temperature-compensated from -40 to +60 °C, so the trip curve stays accurate even in a hot panel or cold environment. Auxiliary contact ratings are given at multiple voltages: 2 A at 24 V, 3 A at 120 V, 2 A at 230 V, 1 A at 400 V — these are the switching capacities for the signal circuit feeding the PLC or contactor coil. Power dissipation per pole is 2.7 W, which matters for thermal management inside a sealed enclosure — three poles dissipate about 8.1 W total. MTTF of 2,280 years under high demand rate. The note \"for message 'Tripped'\" on the relay indicates the auxiliary contact position that signals a trip condition to the control system — a standard feature, not a special marking. Substance prohibitance date of 10/01/2009 confirms RoHS compliance.","metaTitle":"Siemens 3RU2126-4BJ0 SIRIUS Thermal Overload Relay, Class 10","metaDescription":"Siemens 3RU2126-4BJ0 SIRIUS thermal overload relay, Class 10 trip, 690 V rated, S0 size, contactor-mount. Active production. Sourced to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Overload Relays"],"specifications":{"Note":"for message \"Tripped\"","Depth":"85 mm","Width":"45 mm","Height":"85 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","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","For Main Contacts":"M4","Mounting Position":"any","Product Brand Name":"SIRIUS","Product Designation":"thermal overload relay","at 400 V rated value":"7.5 kW","at 480 V rated value":"20 A","at 500 V rated value":"11 kW","at 600 V rated value":"20 A","at 690 V rated value":"15 kW","Size Of Overload Relay":"S0","For Main Current Circuit":"Ring cable lug connection","Temperature Compensation":"-40 ... +60 °C","MTTF with high demand rate":"2 280 y","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":"20 A","For Auxiliary And Control Circuit":"ring terminal lug connection","Between Main And Auxiliary Circuit":"440 V","Relative Humidity During Operation":"10 ... 95 %","Display Version For Switching Status":"Slide switch","For Main Contacts For Ring Cable Lug":"2.5 ... 2 N·m","Surge Voltage Resistance Rated Value":"6 kV","Of The Auxiliary And Control Contacts":"M3","Between Auxiliary And Auxiliary Circuit":"440 V","reference code according to IEC 81346-2":"F","Number Of Poles For Main Current Circuit":"3","For Auxiliary Contacts For Ring Cable Lug":"0.8 ... 1.2 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","operational current at AC-3e at 400 V rated value":"20 A","Size Of Contactor Can Be Combined Company-Specific":"S0","Outer Diameter Of The Usable Ring Cable Lug Maximum":"7.5 mm","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":"14 ... 20 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":null,"sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=111849&mlfb=3RU2126-4BJ0","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RU2126-4BJ0/alternatives.json"},"ai":{"faq":[{"question":"What does the note 'for message Tripped' mean?","answer":"It means the integrated auxiliary switch is wired to signal a trip condition — typically a normally-open contact that closes when the relay trips, sending a signal to a PLC or indicator."},{"question":"What is the physical size of this overload relay?","answer":"It is size S0: 45 mm wide, 85 mm deep, 85 mm high."},{"question":"Does it mount on a DIN rail or directly on a contactor?","answer":"It uses contactor mounting — it snaps directly onto a SIRIUS contactor, not a DIN rail. Any mounting position is allowed."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RU2126-4BJ0","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/3RU2126-4BJ0 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}}