{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RA2120-4DE27-0BB4","brand":"Siemens","brandSlug":"siemens","productSlug":"3RA2120-4DE27-0BB4","canonicalUrl":"https://aoctrl.com/siemens/3RA2120-4DE27-0BB4","factsUrl":"https://aoctrl.com/api/mcp/products/3RA2120-4DE27-0BB4","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS direct online starter, 25 A AC-3 at 400 V, Class 10, 24 VDC coil, size S0, spring-loaded terminals, screw and snap-on mounting onto 35 mm DIN rail.","salesMarkdown":"## 25 A AC-3 at 400 V — what that means for your motor circuit The Siemens 3RA2120-4DE27-0BB4 is a SIRIUS direct online starter rated 25 A in AC-3 duty at 400 V, so it switches standard three-phase squirrel-cage induction motors up to that current — think 11 kW at 400 V, or 20 hp at 460/480 V. The AC-3 rating governs motor starting and plugging, not resistive heating; that's the number that decides whether the contactor survives repetitive inrush. ## Panel fit — size S0, spring terminals, DIN or screw mount This starter lives in the S0 frame — 45 mm wide, 243 mm tall, 107 mm deep — and mounts either by snapping onto a 35 mm DIN rail or with screws through the back. Clearance: 50 mm upward, 20 mm forward, 20 mm to the side, 10 mm downward, zero backward — plan your enclosure depth and gland plate layout around those numbers. ## Coil and control — 24 VDC, no PROFIsafe or PROFINET on this variant The coil is 24 VDC nominal, held in at that voltage. This order code carries no PROFIsafe or PROFINET IO protocol — it's a conventional hardwired starter, not a fieldbus slice. If your safety circuit needs a networked disconnect, you want the -4DE27-0BBx variant with the communication module; this one is for straightforward 24 VDC control from a PLC output or pushbutton station.","metaTitle":"Siemens 3RA2120-4DE27-0BB4 SIRIUS Direct Starter, 25 A AC-3","metaDescription":"Siemens SIRIUS 3RA2120-4DE27-0BB4 direct online starter, 25 A AC-3 at 400 V, Class 10, 24 VDC coil, screw/snap-on DIN rail. Sourced to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Motor Starters"],"specifications":{"Depth":"107 mm","Width":"45 mm","title":"3RA2120-4DE27-0BB4","Height":"243 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 Spring-type 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":"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 standard rail or screw mounting","For Main Current Circuit":"spring-loaded 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":"3RT2027-2BB40","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":"25 A","at AC-3e rated value maximum":"690 V","Substance Prohibitance (Date)":"10/01/2009","at AC-3e at 400 V rated value":"25 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":"3RV2021-4DA20","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":"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/768dcde31cae0b6f4849b564981ba7f4.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=523732&mlfb=3RA2120-4DE27-0BB4"},"ai":{"faq":[],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RA2120-4DE27-0BB4","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/3RA2120-4DE27-0BB4 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}}