{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RA2120-4EE27-0BB4","brand":"Siemens","brandSlug":"siemens","productSlug":"3RA2120-4EE27-0BB4","canonicalUrl":"https://aoctrl.com/siemens/3RA2120-4EE27-0BB4","factsUrl":"https://aoctrl.com/api/mcp/products/3RA2120-4EE27-0BB4","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS direct (on-line) starter, size S0, 29 A at 400 V AC-3, Class 10 trip, 24 VDC coil, spring-loaded terminals, screw and snap-on 35 mm DIN rail mounting.","salesMarkdown":"## SIRIUS S0 direct starter — 29 A AC-3, Class 10, 24 VDC The Siemens 3RA2120-4EE27-0BB4 is a SIRIUS direct (on-line) starter in size S0, combining a contactor and overload relay in one assembly for motor starting and protection. A Class 10 is the most common choice for general-purpose conveyors, pumps, and fans — it protects the motor without nuisance tripping on a normal start. The coil is rated 24 VDC, a standard control voltage for PLC-driven panels and safety circuits. The unit ships with the supplied contactor 3RT2027-2BB40 and link module 3RA2921-2AA00, meaning it arrives as a complete, pre-assembled starter — no separate wiring between contactor and overload. ## Mounting and wiring — DIN rail, spring terminals, S0 footprint The S0 size footprint is 45 mm wide × 107 mm deep × 243 mm tall — the width is the key panel-space constraint; at 45 mm it fits a standard 8-module DIN rail slot with room for adjacent devices. Clearance requirements: 50 mm upwards, 20 mm forwards, 20 mm at the side, 10 mm downwards, and zero backwards. The zero backwards clearance means it can sit flush against the back panel or a busbar without needing an air gap behind it. Main circuit connections use spring-loaded terminals — push-in or screwdriver-actuated, no re-torquing needed. This is faster for panel building than screw terminals and holds well under vibration. ## Lifecycle and sourcing — current production, quoted to order Operating ambient range is -20 to +60 °C, with storage and transport range from -50 to +80 °C.","metaTitle":"Siemens 3RA2120-4EE27-0BB4 SIRIUS Direct Starter, 29 A AC-3","metaDescription":"Siemens 3RA2120-4EE27-0BB4 SIRIUS direct online starter, 29 A at 400 V AC-3, Class 10 trip, 24 VDC coil. Current production, quoted to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Motor Starters"],"specifications":{"Depth":"107 mm","Width":"45 mm","title":"3RA2120-4EE27-0BB4","Height":"243 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 27.0...32.0 A 24 V DC Spring-type terminal for installation on standard mounting rail (also fulfills type of coordination 1) Type of coordination 2, Iq = 150 kA 1 NO+1 NC (contactor)","During Storage":"-50 ... +80 °C","lifecycle_stage":"current","During Operation":"-20 ... +60 °C","During Transport":"-50 ... +80 °C","Fastening Method":"screw and snap-on mounting onto 35 mm DIN rail","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 230 V rated value":"5 hp","at 400 V rated value":"15 000 kW","at 480 V rated value":"27 A","at 600 V rated value":"27 A","Design Of The Product":"for standard rail or screw mounting","For Main Current Circuit":"spring-loaded terminals","Temperature Compensation":"-20 ... +60 °C","at 110/120 V rated value":"2 hp","at 200/208 V rated value":"10 hp","at 220/230 V rated value":"10 hp","at 460/480 V rated value":"20 hp","Of The Supplied Contactor":"3RT2027-2BB40","Of The Supplied Link Module":"3RA2921-2AA00","Size Of The Circuit-Breaker":"S0","at AC-3 rated value maximum":"690 V","at AC-3 at 400 V rated value":"29 A","at AC-3e rated value maximum":"690 V","Substance Prohibitance (Date)":"10/01/2009","at AC-3e at 400 V rated value":"29 A","Design Of The Overload Release":"thermal (bimetallic)","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":"3RV2021-4EA20","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 %","Without Load Current Share Typical":"5.9 W","holding power of magnet coil at DC":"5.9 W","Surge Voltage Resistance Rated Value":"6 kV","at AC in hot operating state per pole":"6.7 W","Number Of Poles For Main Current Circuit":"3","Product Function Short Circuit Protection":"Yes","protocol is supported AS-Interface protocol":"No","with high demand rate according to SN 31920":"73 %","reference code according to IEC 81346-2:2019":"Q","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","Mechanical Service Life (Operating Cycles) Of Contactor Typical":"10 000 000","Response Value Current Of Instantaneous Short-Circuit Trip Unit":"400 A","insulation voltage with degree of pollution 3 at AC rated value":"690 V","Adjustable Current Response Value Current Of The Current-Dependent Overload Release":"27 ... 32 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/c1ed2c387f562077ae86a7dc54026657.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=58893&mlfb=3RA2120-4EE27-0BB4"},"ai":{"faq":[{"question":"What is the AC-3 rating of 3RA2120-4EE27-0BB4?","answer":"This is the motor-switching current — the starter is designed for three-phase induction motor loads up to that full-load current."},{"question":"What compliance documentation does Siemens provide for 3RA2120-4EE27-0BB4?","answer":"Standard Siemens documentation includes the CE declaration of conformity and the product datasheet; UL and CSA listings are typical for the SIRIUS family but should be confirmed against the specific variant at order time."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RA2120-4EE27-0BB4","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/3RA2120-4EE27-0BB4 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}}