{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RA2120-4AA26-0BB4","brand":"Siemens","brandSlug":"siemens","productSlug":"3RA2120-4AA26-0BB4","canonicalUrl":"https://aoctrl.com/siemens/3RA2120-4AA26-0BB4","factsUrl":"https://aoctrl.com/api/mcp/products/3RA2120-4AA26-0BB4","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS direct online starter, size S0, 3RA2120-4AA26-0BB4, 16 A AC-3 at 400 V, Class 10, 24 V DC coil, screw terminals.","salesMarkdown":"The Siemens 3RA2120-4AA26-0BB4 is a SIRIUS direct online starter in size S0 — a pre-assembled combination of a contactor and a thermal overload relay, intended for switching and protecting three-phase motors. It comes supplied with a 3RT2026-1BB40 contactor and a 3RA2921-1BA00 link module, so the coordination between the two is factory-set, not something you tune on the bench. The coil is rated 24 V DC, so confirm your control voltage matches — this is not a 24 V AC or 110 V variant. ## Mounting and fit The S0 frame takes a 45 mm wide footprint on the rail, and the depth of 107 mm means it clears most standard enclosures — but check your door clearance if the starter sits near the hinge side. Clearance spaces: 50 mm upward, 20 mm forward, 20 mm to the side, 10 mm downward. Zero clearance needed behind the unit. That forward clearance is the main gotcha — if you're packing starters tight in a shallow panel, the 20 mm forward allowance for arc venting and wiring bend radius is real, not a suggestion. RoHS compliance date is 2009-10-01, covering the substance prohibitions under the EU directive. No REACH or UL listing is explicitly stated in the spec record, but the SIRIUS family typically carries UL/CSA certification — verify the specific approval mark on the nameplate if your panel requires it.","metaTitle":"Siemens 3RA2120-4AA26-0BB4 SIRIUS Direct Starter, 16 A AC-3,","metaDescription":"Siemens SIRIUS 3RA2120-4AA26-0BB4 direct online starter, size S0, 16 A AC-3 at 400 V, Class 10 trip, 24 V coil. Active production, RoHS compliant. Sourced 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":"3RA2120-4AA26-0BB4","Height":"193 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 10...16 A 24 V DC screw 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":"2 hp","at 400 V rated value":"7 500 kW","at 480 V rated value":"16 A","at 600 V rated value":"16 A","Design Of The Product":"for standard rail or screw mounting","For Main Current Circuit":"screw-type terminals","Temperature Compensation":"-20 ... +60 °C","at 110/120 V rated value":"1 hp","at 200/208 V rated value":"2 hp","at 220/230 V rated value":"5 hp","at 460/480 V rated value":"10 hp","Of The Supplied Contactor":"3RT2026-1BB40","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":"16 A","at AC-3e rated value maximum":"690 V","Substance Prohibitance (Date)":"10/01/2009","at AC-3e at 400 V rated value":"16 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":"3RV2021-4AA10","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 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":"208 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":"10 ... 16 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$129.54","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/ac7bc7b061298721577498a3c5b22cf1.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=512004&mlfb=3RA2120-4AA26-0BB4"},"ai":{"faq":[{"question":"What are the key ratings for this direct starter?","answer":"AC-3 rated current is 16 A at 400 V, with a maximum operating voltage of 690 V. The thermal overload relay is Class 10. The coil is 24 V DC. Horsepower equivalents: 5 hp at 220/230 V, 10 hp at 460/480 V."},{"question":"What is the physical size and mounting requirement?","answer":"Size S0 frame: 45 mm wide, 193 mm tall, 107 mm deep. Mounts vertically on 35 mm DIN rail or with screws. Requires 50 mm clearance above, 20 mm forward, 20 mm to the side, 10 mm below, and zero behind."},{"question":"What contactor and link module are supplied with this starter?","answer":"It ships with a 3RT2026-1BB40 contactor and a 3RA2921-1BA00 link module, factory-assembled for coordinated motor protection."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RA2120-4AA26-0BB4","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/3RA2120-4AA26-0BB4 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}}