{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RA2120-4BD27-0FB4","brand":"Siemens","brandSlug":"siemens","productSlug":"3RA2120-4BD27-0FB4","canonicalUrl":"https://aoctrl.com/siemens/3RA2120-4BD27-0FB4","factsUrl":"https://aoctrl.com/api/mcp/products/3RA2120-4BD27-0FB4","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RA2120-4BD27-0FB4 direct online starter, Size S0, 20 A AC-3 at 400 V, Class 10 trip, screw terminals, for 60 mm busbar systems.","salesMarkdown":"## Busbar snap-on and panel fit The 3RA2120-4BD27-0FB4: Mounts by snapping onto 60 mm busbar systems — no DIN rail needed. The 45 mm width and 165 mm depth fit into a standard S0 feeder slot; vertical mounting position only, with 50 mm clearance above and 20 mm at the side for cooling and wiring access. The supplied contactor is a 3RT2027-1FB40, and the link module is 3RA2921-1BA00 — pre-assembled as a single order code, so no separate sourcing for the contactor and overload. ## Lifecycle and sourcing — active, quoted to order Sourced through authorized distribution against the BOM quantity; availability and pricing confirmed at RFQ time.","metaTitle":"Siemens 3RA2120-4BD27-0FB4 SIRIUS Direct Starter, 20 A AC-3","metaDescription":"Siemens 3RA2120-4BD27-0FB4 SIRIUS direct online starter, 20 A AC-3 at 400 V, Class 10, snaps onto 60 mm busbars.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Motor Starters"],"specifications":{"Depth":"165 mm","Width":"45 mm","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","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":"7 500 kW","at 480 V rated value":"20 A","at 600 V rated value":"20 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":"1.5 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":"15 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":"20 A","at AC-3e rated value maximum":"690 V","at AC-3e at 400 V rated value":"20 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":"3RV2021-4BA10","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":"260 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":"13 ... 20 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/c96c32f137d156870048e2889d8685cb.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=300566&mlfb=3RA2120-4BD27-0FB4","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RA2120-4BD27-0FB4/alternatives.json"},"ai":{"faq":[{"question":"What is the AC-3 current rating at 400 V for this starter?","answer":"That's the motor-switching current that governs contact life and overload setting — not the thermal continuous current, which is higher."},{"question":"Does this starter include the contactor and overload relay, or do I need to buy them separately?","answer":"It ships as a complete direct-on-line starter with the 3RT2027-1FB40 contactor and the 3RA2921-1BA00 link module pre-assembled. One order code, one unit."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RA2120-4BD27-0FB4","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/3RA2120-4BD27-0FB4 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}}