{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RA2120-4AD26-0BB4","brand":"Siemens","brandSlug":"siemens","productSlug":"3RA2120-4AD26-0BB4","canonicalUrl":"https://aoctrl.com/siemens/3RA2120-4AD26-0BB4","factsUrl":"https://aoctrl.com/api/mcp/products/3RA2120-4AD26-0BB4","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RA2120-4AD26-0BB4 direct-on-line starter, size S0, 16 A at 400 V AC-3, Class 10 trip, for 60 mm busbar systems, screw terminals.","salesMarkdown":"## What the 16 A AC-3 rating means for motor starting The 3RA2120-4AD26-0BB4: The 16 A at 400 V AC-3 rating covers standard squirrel-cage motor starting — breaking the stalled rotor current, not just the running load. Class 10 trip means the overload relay will open within 10 seconds at 7.2x the current setting — tight enough to protect the motor winding during a stall without nuisance tripping on a normal start. Maximum AC-3 voltage is 690 V, so this starter can also serve 480 V or 600 V motor circuits at the same 16 A rating. ## Busbar snap-on and panel layout constraints This S0-size starter snaps directly onto 60 mm busbar systems — no DIN rail adapter needed. That saves a mounting step and keeps the assembly height predictable. The footprint is 45 mm wide by 260 mm tall by 165 mm deep. Clearance requirements: 50 mm above, 20 mm in front, 20 mm at the sides, and 10 mm below — zero behind. Plan the enclosure depth around the 165 mm plus the 20 mm forward clearance. Mounting position is vertical only. The supplied contactor is a 3RT2026-1BB40 and the link module is 3RA2921-1BA00 — both factory-integrated, so no loose parts to order separately. RoHS compliance date is 10/01/2009 — the starter meets the European substance restrictions for current production.","metaTitle":"Siemens 3RA2120-4AD26-0BB4 SIRIUS DOL Starter, 16 A AC-3, S0","metaDescription":"Siemens 3RA2120-4AD26-0BB4 SIRIUS direct-on-line starter, 16 A at 400 V AC-3, size S0, Class 10 trip. Snaps onto 60 mm busbars. Current lifecycle stage.","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":"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 60 mm busbars","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)","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":"3RV2021-4AA10","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":null,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/a1946e9378c7ac11f48ea3a8c39fc04e.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=39017&mlfb=3RA2120-4AD26-0BB4","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RA2120-4AD26-0BB4/alternatives.json"},"ai":{"faq":[{"question":"What is the AC-3 current rating of this starter at 400 V?","answer":"16 A at 400 V AC-3. This is the motor-switching current, covering the inrush during starting. The maximum AC-3 voltage is 690 V."},{"question":"What compliance documentation does Siemens provide for 3RA2120-4AD26-0BB4?","answer":"The RoHS compliance date is 10/01/2009. The starter is manufactured to meet EU substance restrictions. Additional certifications (UL, CSA, CE) are standard for the SIRIUS series but are not individually listed in the available spec data."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RA2120-4AD26-0BB4","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/3RA2120-4AD26-0BB4 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}}