{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RU2126-4BC1","brand":"Siemens","brandSlug":"siemens","productSlug":"3RU2126-4BC1","canonicalUrl":"https://aoctrl.com/siemens/3RU2126-4BC1","factsUrl":"https://aoctrl.com/api/mcp/products/3RU2126-4BC1","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS thermal overload relay, size S0, trip class 10, 690 V rated, 3RU2126-4BC1, spring-loaded terminals.","salesMarkdown":"## What this relay does and how it fits It uses a thermal bimetallic release and integrates the auxiliary switch directly into the housing. Rated at 690 V with a maximum AC-3e switching voltage of 690 V, it handles motor circuits up to 7.5 kW at 400 V, 11 kW at 500 V, and 15 kW at 690 V. The auxiliary contact ratings span the control-voltage range you are likely to find in a panel: 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. That covers most PLC output cards and contactor coils without a separate interposing relay. The size S0 is the most common frame for motor starters up to about 15 kW; it mates with the corresponding S0 contactor (3RT10 series) without adapters. Spring-loaded terminals accept 2 × (0.5 to 2.5 mm²) solid or stranded wire, which speeds up wiring compared to screw terminals and holds better under vibration. The physical dimensions — 114 mm height, 45 mm width, 95 mm depth — fit the standard S0 slot. If you are replacing a failed relay in an existing panel, measure the depth clearance: 95 mm is shallower than some older European designs, so it should drop in without hitting the backplane or gland plate. The spring-loaded terminals require a screwdriver with a 3 mm shaft diameter and a 3.0 × 0.5 mm tip — a standard slotted driver, nothing special. Temperature compensation is active from -40 to +60 °C. The MTTF under high-demand operation is 2,280 years. The relay carries a substance prohibition date of 10/01/2009, which aligns with the original RoHS directive (RoHS 1). Current production complies with RoHS 2/3 and REACH. The SIRIUS family is designed to IEC 60947-4-1 and carries UL/CSA approvals for the North American market. A full declaration of conformity and the technical datasheet are available from Siemens Industry Online Support.","metaTitle":"Siemens 3RU2126-4BC1 SIRIUS Thermal Overload Relay, Size S0,","metaDescription":"Siemens 3RU2126-4BC1 SIRIUS thermal overload relay, size S0, trip class 10, 690 V rated, spring-loaded terminals. Current lifecycle stage. Sourced to order against 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":"114 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","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":"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":"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":"20 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":"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":"$36.83","priceTiers":null},"links":{"datasheetUrl":null,"sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=481093&mlfb=3RU2126-4BC1","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RU2126-4BC1/alternatives.json"},"ai":{"faq":[{"question":"What is 3RU2126-4BC1's listed note (for message \"Tripped\") on this component line?","answer":"The note on the component line reads \"for message 'Tripped'\". This identifies the auxiliary contact function — it closes (or opens) when the overload relay has tripped, providing a signal to a PLC input or an indicator lamp."},{"question":"What is 3RU2126-4BC1's listed depth (95 mm) on this component line?","answer":"The depth is 95 mm. This is the dimension from the mounting surface to the front of the relay housing. It is shallower than some older European designs, so it fits most standard enclosures without depth clearance issues."},{"question":"When sourcing 3RU2126-4BC1, what's the closest functional second-source — 3RV1011-1HA10?","answer":"The 3RV1011-1HA10 is a circuit breaker, not a thermal overload relay — it combines short-circuit and overload protection in one device. It will not drop into the same panel without rewiring because the 3RU2126-4BC1 is designed to pair with a contactor in a motor starter configuration, while the 3RV1011-1HA10 is a standalone protective device. The closest functional match within the same SIRIUS family is the 3RU2 series in the same size S0 frame; the 3RV1011-1HA10 is a different product class."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RU2126-4BC1","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/3RU2126-4BC1 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}}