{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RU2126-4BB1","brand":"Siemens","brandSlug":"siemens","productSlug":"3RU2126-4BB1","canonicalUrl":"https://aoctrl.com/siemens/3RU2126-4BB1","factsUrl":"https://aoctrl.com/api/mcp/products/3RU2126-4BB1","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RU2126-4BB1 thermal overload relay, Class 10, S0 size, 690 V rated, auxiliary contacts rated 2 A at 24 V, screw terminals.","salesMarkdown":"## Thermal Overload Relay for Motor Protection It is a standalone-mount unit with screw-type terminals for the main circuit, accepting 2x (0.5...1.5 mm²) or 2x (0.75...2.5 mm²) solid or stranded wire. Rated voltage is 690 V, with corresponding motor power ratings of 7.5 kW at 400 V, 11 kW at 500 V, and 15 kW at 690 V. At 480 V and 600 V the current rating is 20 A. The auxiliary switch is integrated and carries the following contact ratings: 2 A at 24 V, 3 A at 120 V, 2 A at 230 V, 1 A at 400 V, and 0.75 A at 690 V — these are the values you'd use for the trip-indication circuit back to the PLC or annunciator. The relay measures 97 mm high, 45 mm wide, and 95 mm deep — the S0 footprint that drops into a standard motor starter assembly or stands alone on a panel plate. Main circuit terminals accept M4 screws; the screwdriver spec is Pozidriv PZ2 with a 5–6 mm shaft diameter.","metaTitle":"Siemens 3RU2126-4BB1 SIRIUS Thermal Overload Relay, Class 10","metaDescription":"Siemens 3RU2126-4BB1 SIRIUS thermal overload relay, Class 10, S0 size, 690 V rated, auxiliary contacts rated 2 A at 24 V. Active production, sourced to order. Request 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":"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":"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":"20 A","for 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","Of The Auxiliary And Control Contacts":"M3","for AWG cables for auxiliary contacts":"2x (20 ... 16), 2x (18 ... 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","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":"20 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":"14 ... 20 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/bfe694cf0bf950dfe5617f9b66b9ded2.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=63577&mlfb=3RU2126-4BB1","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RU2126-4BB1/alternatives.json"},"ai":{"faq":[{"question":"What is the note 'for message Tripped' on the 3RU2126-4BB1?","answer":"The note indicates that the auxiliary contact configuration is wired to signal a 'Tripped' condition — the integrated auxiliary switch changes state when the relay has operated due to overload or phase failure, providing a dry contact for the control system."},{"question":"How does the 3RU2126-4BB1 compare to the 3RU2116-1FC1?","answer":"The 3RU2116-1FC1 is a smaller S00-frame relay with lower current ranges and a different trip class. The 3RU2126-4BB1 is the S0-frame version with higher power ratings (7.5 kW at 400 V vs. lower) and a Class 10 trip characteristic. They are not direct drop-in replacements due to different frame sizes and terminal layouts."},{"question":"What compliance documentation does Siemens provide for the 3RU2126-4BB1?","answer":"The relay carries a substance prohibition date of October 1, 2009, indicating RoHS compliance. Standard Siemens documentation includes a CE declaration of conformity and the product datasheet with full technical specifications."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RU2126-4BB1","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/3RU2126-4BB1 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}}