{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RA2125-4ED27-0BB4","brand":"Siemens","brandSlug":"siemens","productSlug":"3RA2125-4ED27-0BB4","canonicalUrl":"https://aoctrl.com/siemens/3RA2125-4ED27-0BB4","factsUrl":"https://aoctrl.com/api/mcp/products/3RA2125-4ED27-0BB4","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RA2125-4ED27-0BB4 non-fused motor starter, size S0, direct starter, 27 A at 480 V, Class 10, 24 V coil, electromechanical switching contact, thermal bimetallic overload release, magnetic short-circuit trip, 50/60 Hz, vertical mounting, snap-on 60 mm busbar.","salesMarkdown":"## Motor starter assembly — what ships and what it covers The 3RA2125-4ED27-0BB4 is a SIRIUS non-fused motor starter, size S0, combining a contactor and overload relay in one direct-starter package. It ships with the 3RT2027-1BB40 contactor, the 3RA2921-1BA00 link module, and the 8US1251-5NT10 busbar adapter — the BOM line is a complete feeder, not a loose contactor. The 24 V coil (50/60 Hz) pulls from a standard control transformer. ## Overload and short-circuit protection — Class 10 trip curve The magnetic short-circuit trip handles the instantaneous fault clearing. Pollution degree 3 (conductive pollution or dry non-conductive pollution that becomes conductive due to condensation) is the design environment — this starter is rated for industrial control panels where the atmosphere is not climate-controlled. ## Panel fit and mounting — vertical snap-on, 60 mm busbar Mounting is vertical only, snapping onto 60 mm busbar systems via the included adapter. The footprint is 45 mm wide × 260 mm high × 165 mm deep — the S0 frame size keeps the width to a single 45 mm module, so it fits standard 600 mm wide enclosures with room for gland plates and wiring ducts. Clearance requirements: 30 mm upwards, 10 mm forwards, 10 mm downwards, 9 mm at the side, and 0 mm backwards — the back face sits flush against the mounting surface. No rear gap means the busbar adapter must be seated before the starter is snapped on. The supplied sub-components (contactor 3RT2027-1BB40, link module 3RA2921-1BA00, busbar adapter 8US1251-5NT10) are each individually orderable as spares, but the 3RA2125-4ED27-0BB4 assembly is the single BOM line for a complete feeder — no separate sourcing of contactor and overload relay.","metaTitle":"Siemens 3RA2125-4ED27-0BB4 SIRIUS Motor Starter","metaDescription":"Siemens 3RA2125-4ED27-0BB4 SIRIUS non-fused motor starter, size S0, 27 A at 480 V, Class 10 thermal overload. Active production, quoted to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Motor Starters"],"specifications":{"Depth":"165 mm","Width":"45 mm","title":"3RA2125-4ED27-0BB4","Height":"260 mm","Upwards":"30 mm","Forwards":"10 mm","Backwards":"0 mm","Downwards":"10 mm","Trip Class":"CLASS 10","At The Side":"9 mm","Rated Value":"24 V","description":"FUSELESS MOTOR STARTER DIRECT START 600V AC SZ S0 27-32A 24V DC SCREW CONNECTION FOR SNAPPING ONTO 60 MM BUSBAR SYSTEMS TYPE OF COORDINATION 2 IQ = 150 KA ALSO FULFILLS TYPE OF COORDINATION 1 1NO+1NC (MSP) 1NO+1NC (CONTACTOR)","During Storage":"-50 ... +80 °C","lifecycle_stage":"current","During Operation":"-20 ... +60 °C","During Transport":"-55 ... +80 °C","Fastening Method":"for snapping onto 60 mm busbar systems","Mounting Position":"vertical","Product Brand Name":"SIRIUS","Type Of Assignment":"2","Degree Of Pollution":"3","Product Designation":"non-fused motor starter 3RA2","Size Of Load Feeder":"S0","at 230 V rated value":"5 hp","at 400 V rated value":"15 000 W","at 480 V rated value":"27 A","at 500 V rated value":"18 500 W","at 600 V rated value":"27 A","Design Of The Product":"direct starter","at 200/208 V rated value":"10 hp","at 220/230 V rated value":"10 hp","at 460/480 V rated value":"20 hp","at 575/600 V rated value":"25 hp","Of The Supplied Contactor":"3RT2027-1BB40","Of The Supplied Link Module":"3RA2921-1BA00","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":"8US1251-5NT10","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":"3RV2021-4EA15","Product Extension Auxiliary Switch":"Yes","holding power of magnet coil at DC":"5.9 W","Surge Voltage Resistance Rated Value":"6 kV","Number Of Poles For Main Current Circuit":"3","Product Function Short Circuit Protection":"Yes","number of NC contacts for auxiliary contacts":"2","number of NO contacts for auxiliary contacts":"2","shock resistance according to IEC 60068-2-27":"6g / 11 ms","at 400 V according to IEC 60947-4-1 rated value":"153 000 A","at 500 V according to IEC 60947-4-1 rated value":"100 000 A","operational current at AC-3 at 400 V rated value":"29 A","Type Of Electrical Connection For Main Current Circuit":"screw-type terminals","Mechanical Service Life (Operating Cycles) Of Contactor Typical":"10 000 000","Response Value Current Of Instantaneous Short-Circuit Trip Unit":"416 A","insulation voltage with degree of pollution 3 at AC rated value":"690 V","Type Of Connectable Conductor Cross-Sections For Main Contacts Stranded":"1 ... 10 mm², 2x (2.5 ... 6 mm²)","Adjustable Current Response Value Current Of The Current-Dependent Overload Release":"27 ... 32 A","Connectable Conductor Cross-Section For Main Contacts Finely Stranded With Core End Processing":"1 ... 6 mm²"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/32332b7c4a2f9de5e149c3ff52845329.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=146741&mlfb=3RA2125-4ED27-0BB4"},"ai":{"faq":[{"question":"What motor power does 3RA2125-4ED27-0BB4 cover at 480 V?","answer":"The thermal Class 10 overload protects standard induction motors during locked-rotor conditions."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RA2125-4ED27-0BB4","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/3RA2125-4ED27-0BB4 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-07-22T19:47:38.189Z","lastPublished":"2026-07-22T19:47:38.189Z","indexable":true}}