{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RA2125-4CH27-0FB4","brand":"Siemens","brandSlug":"siemens","productSlug":"3RA2125-4CH27-0FB4","canonicalUrl":"https://aoctrl.com/siemens/3RA2125-4CH27-0FB4","factsUrl":"https://aoctrl.com/api/mcp/products/3RA2125-4CH27-0FB4","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RA2125-4CH27-0FB4 direct-on-line starter, S0 size, 11 kW at 400 V AC-3, Class 10, 24 V DC coil, snap-on 60 mm busbar mount, spring-loaded terminals.","salesMarkdown":"## 11 kW at 400 V — what the AC-3 rating means for the motor line The 3RA2125-4CH27-0FB4: The 24 V DC control coil (24... 24 V) keeps the control circuit isolated from the motor power side, which simplifies integration with a PLC or safety relay panel. ## Snap-on busbar mount — panel integration without extra rail This starter is designed for snapping onto 60 mm busbar systems — no separate DIN rail needed. The S0 footprint (45 mm wide, 165 mm deep, 260 mm high) matches the standard SIRIUS feeder size, so it drops into existing S0 busbar layouts. Mounting position is vertical only. Clearance requirements: 50 mm upwards, 20 mm forwards, 10 mm downwards, 20 mm at the side, and 0 mm backwards — meaning the back can sit flush against the panel wall. Spring-loaded terminals on both the main current circuit and the auxiliary/control circuit — no screw torque to verify, just strip and insert. ## Supplied as a pre-assembled set — what's in the box The 3RA2125-4CH27-0FB4 ships as a complete feeder set: a 3RT2027-2FB40 contactor, a 3RV2021-4CA25 circuit breaker (magnetic short-circuit trip, thermal bimetallic overload), a 3RA2921-2AA00 link module, and a 8US1251-5NT11 busbar adapter. No separate ordering of subcomponents. The supplied contactor and circuit breaker are both size S0, so the assembly stays within the same frame and busbar pitch. No stock-holding claim — quoted per order.","metaTitle":"Siemens 3RA2125-4CH27-0FB4 SIRIUS Motor Starter","metaDescription":"Siemens 3RA2125-4CH27-0FB4 SIRIUS direct-on-line starter, S0 size, 11 kW at 400 V AC-3, Class 10, 24 V DC coil. Snap-on 60 mm busbar mount. Quoted to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Motor Starters"],"specifications":{"Depth":"165 mm","Width":"45 mm","title":"3RA2125-4CH27-0FB4","Height":"260 mm","Upwards":"50 mm","Forwards":"20 mm","Backwards":"0 mm","Downwards":"10 mm","Trip Class":"CLASS 10","At The Side":"20 mm","Rated Value":"24 ... 24 V","description":"Load feeder fuseless, Direct-on-line starting 400 V AC, Size S0 16...22 A 24 V DC Spring-type terminal for 60 mm busbar systems (also fulfills type of coordination 1) Type of coordination 2, Iq = 150 kA 1 NO+1 NC (contactor) with diode combination plugged in at the front","During Storage":"-50 ... +80 °C","lifecycle_stage":"current","During Operation":"-20 ... +60 °C","During Transport":"-50 ... +80 °C","Fastening Method":"for snapping onto 60 mm busbar systems","Mounting Position":"vertical","PROFIsafe protocol":"No","Product Brand Name":"SIRIUS","Type Of Assignment":"2","Product Designation":"Direct (on-line) starter","Size Of Load Feeder":"S0","PROFINET IO protocol":"No","at 400 V rated value":"11 000 W","Design Of The Product":"for 60 mm busbars","For Main Current Circuit":"spring-loaded terminals","Temperature Compensation":"-20 ... +60 °C","Of The Supplied Contactor":"3RT2027-2FB40","Of The Supplied Link Module":"3RA2921-2AA00","Size Of The Circuit-Breaker":"S0","at AC-3 rated value maximum":"690 V","Design Of The Overload Release":"thermal (bimetallic)","Of The Supplied Busbar Adapter":"8US1251-5NT11","Design Of The Switching Contact":"electromechanical","Operating Frequency Rated Value":"50 ... 60 Hz","Design Of The Short-Circuit Trip":"magnetic","Of The Supplied Circuit-Breakers":"3RV2021-4CA25","degree of protection NEMA rating":"other","For Auxiliary And Control Circuit":"spring-loaded terminals","Product Extension Auxiliary Switch":"Yes","Relative Humidity During Operation":"10 ... 95 %","Surge Voltage Resistance Rated Value":"6 kV","Number Of Poles For Main Current Circuit":"3","Product Function Short Circuit Protection":"Yes","protocol is supported AS-Interface protocol":"No","number of NC contacts for auxiliary contacts":"1","number of NO contacts for auxiliary contacts":"1","shock resistance according to IEC 60068-2-27":"6g / 11 ms","Type Of Voltage Of The Control Supply Voltage":"DC","at 400 V according to IEC 60947-4-1 rated value":"150 000 A","operational current at AC-3 at 400 V rated value":"22 A","Mechanical Service Life (Switching Cycles) Of Contactor Typical":"10 000 000","insulation voltage with degree of pollution 3 at AC rated value":"690 V","Adjustable Current Response Value Current Of The Current-Dependent Overload Release":"16 ... 22 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/dbc72f6de198704d0b423451df58d07e.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=553483&mlfb=3RA2125-4CH27-0FB4"},"ai":{"faq":[{"question":"What compliance documentation does Siemens provide for 3RA2125-4CH27-0FB4?","answer":"The product carries Siemens standard compliance documentation for RoHS, REACH, and relevant IEC/UL standards — confirm specific certificate requirements at RFQ."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RA2125-4CH27-0FB4","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/3RA2125-4CH27-0FB4 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}}