{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RA2120-4CH27-0BB4","brand":"Siemens","brandSlug":"siemens","productSlug":"3RA2120-4CH27-0BB4","canonicalUrl":"https://aoctrl.com/siemens/3RA2120-4CH27-0BB4","factsUrl":"https://aoctrl.com/api/mcp/products/3RA2120-4CH27-0BB4","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS direct (on-line) starter, Size S0, 22 A AC-3 at 400 V, Trip Class 10, spring-loaded terminals, for 60 mm busbar systems.","salesMarkdown":"The Siemens 3RA2120-4CH27-0BB4 is a SIRIUS direct (on-line) starter in Size S0, combining a contactor and overload relay into one unit that snaps onto 60 mm busbar systems. Its AC-3 rating of 22 A at 400 V means it switches three-phase motor loads up to that current under full-load starts — typical for conveyors, pumps, and fans in a control panel. The Trip Class 10 overload curve trips within 10 seconds at 7.2× rated current, protecting standard induction motors during stall or jam conditions without nuisance tripping on normal acceleration. Rated 22 A in AC-3 at 400 V, with a maximum operating voltage of 690 V AC-3. The 24 V control coil keeps it compatible with standard PLC output cards or control transformers. The starter is designed for vertical mounting and needs 50 mm clearance upwards, 20 mm forwards, 10 mm downwards, and 20 mm at the side (–). That 260 mm height and 45 mm width fit a standard 60 mm busbar footprint without crowding adjacent feeders.","metaTitle":"Siemens 3RA2120-4CH27-0BB4 SIRIUS DOL Starter, 22 A AC-3","metaDescription":"Siemens 3RA2120-4CH27-0BB4 SIRIUS direct-on-line starter, 22 A at 400 V AC-3, Trip Class 10, Size S0, snaps onto 60 mm busbars. Current lifecycle.","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":"11 000 kW","at 480 V rated value":"22 A","at 600 V rated value":"22 A","Design Of The Product":"for 60 mm busbars","For Main Current Circuit":"spring-loaded 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":"3RT2027-2BB40","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":"22 A","at AC-3e rated value maximum":"690 V","Substance Prohibitance (Date)":"10/01/2009","at AC-3e at 400 V rated value":"22 A","Design Of The Overload Release":"thermal (bimetallic)","Of The Supplied Busbar Adapter":"8US1251-5NT11","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":"3RV2021-4CA20","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":"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":"286 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":"16 ... 22 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/73f3aa16db99a32e5b0d2fb4804c66f6.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=457802&mlfb=3RA2120-4CH27-0BB4","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RA2120-4CH27-0BB4/alternatives.json"},"ai":{"faq":[{"question":"What voltage does 3RA2120-4CH27-0BB4 operate at?","answer":"The control coil is rated 24 V. The main circuit is rated for AC-3 operation up to 690 V maximum."},{"question":"Where can I buy the 3RA2120-4CH27-0BB4?","answer":"This part is sourced to order; availability and pricing are confirmed at quote time. Contact our sales team for current lead time and pricing."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RA2120-4CH27-0BB4","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/3RA2120-4CH27-0BB4 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}}