{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RA2120-4DD27-0FB4","brand":"Siemens","brandSlug":"siemens","productSlug":"3RA2120-4DD27-0FB4","canonicalUrl":"https://aoctrl.com/siemens/3RA2120-4DD27-0FB4","factsUrl":"https://aoctrl.com/api/mcp/products/3RA2120-4DD27-0FB4","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RA2120-4DD27-0FB4 direct (on-line) starter, size S0, 25 A at 400 V AC-3, Class 10 trip, for 60 mm busbar systems, screw-type terminals.","salesMarkdown":"## SIRIUS S0 direct starter — 25 A AC-3, snaps onto 60 mm busbars The 3RA2120-4DD27-0FB4: It ships as a pre-assembled unit: the supplied contactor is 3RT2027-1FB40 and the link module is 3RA2921-1BA00, so it lands on the shelf ready to snap onto a 60 mm busbar system without piecing together separate components. ## Panel fit and clearance — size S0 on 60 mm busbars The starter measures 45 mm wide by 260 mm high by 165 mm deep, and is designed to snap vertically onto a 60 mm busbar system — no DIN rail adapter needed, it clips directly onto the busbar profile. Clearance requirements: 50 mm upwards, 20 mm forwards, 20 mm at the side, 10 mm downwards, and 0 mm backwards — the back of the unit sits flush against the panel backplane, so plan the busbar depth accordingly. Main circuit connections are screw-type terminals, sized for the S0 frame — expect to land up to 25 A motor feeders with standard ring or fork lugs. ## Ambient limits and storage range Operating ambient temperature range is -20 to +60 °C, with the same range for temperature compensation — the overload curve stays accurate across that band without manual adjustment. Storage and transport limits are wider: -50 to +80 °C, so the unit can sit in an unheated warehouse or truck without damage.","metaTitle":"Siemens 3RA2120-4DD27-0FB4 SIRIUS Direct Starter, 25 A AC-3","metaDescription":"Siemens SIRIUS 3RA2120-4DD27-0FB4 direct online starter, 25 A at 400 V AC-3, Class 10 trip, size S0, for 60 mm busbar. Active production, 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":"3RA2120-4DD27-0FB4","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 18...25 A 24 V DC screw 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 230 V rated value":"3 hp","at 400 V rated value":"11 000 kW","at 480 V rated value":"25 A","at 600 V rated value":"25 A","Design Of The Product":"for 60 mm busbars","For Main Current Circuit":"screw-type terminals","Temperature Compensation":"-20 ... +60 °C","at 110/120 V rated value":"2 hp","at 200/208 V rated value":"7.5 hp","at 220/230 V rated value":"7.5 hp","at 460/480 V rated value":"20 hp","Of The Supplied Contactor":"3RT2027-1FB40","Of The Supplied Link Module":"3RA2921-1BA00","Size Of The Circuit-Breaker":"S0","at AC-3 rated value maximum":"690 V","at AC-3 at 400 V rated value":"25 A","at AC-3e rated value maximum":"690 V","at AC-3e at 400 V rated value":"25 A","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":"3RV2021-4DA10","degree of protection NEMA rating":"other","For Auxiliary And Control Circuit":"screw-type 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":"5.8 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":"325 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":"18 ... 25 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/938bd84d90621ba17c083ffaf13c4e2e.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=266051&mlfb=3RA2120-4DD27-0FB4"},"ai":{"faq":[{"question":"What is the AC-3 current rating of this starter at 400 V?","answer":"That is the motor-switching current for a standard induction motor under starting and stopping conditions. The same 25 A rating also applies at 600 V AC-3."},{"question":"What contactor and link module are supplied with this starter?","answer":"The supplied contactor is 3RT2027-1FB40 and the link module is 3RA2921-1BA00. These are pre-assembled at the factory, so the starter arrives as a single unit ready to mount."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RA2120-4DD27-0FB4","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/3RA2120-4DD27-0FB4 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}}