{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RA2125-4CA27-0BB4","brand":"Siemens","brandSlug":"siemens","productSlug":"3RA2125-4CA27-0BB4","canonicalUrl":"https://aoctrl.com/siemens/3RA2125-4CA27-0BB4","factsUrl":"https://aoctrl.com/api/mcp/products/3RA2125-4CA27-0BB4","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RA2125-4CA27-0BB4 non-fused motor starter, size S0, direct starter, CLASS 10 thermal bimetallic overload, 24 V rated control voltage, 50/60 Hz, snap-on DIN rail.","salesMarkdown":"## Integrated motor starter assembly — what ships in the box The 3RA2125-4CA27-0BB4 is a SIRIUS non-fused direct motor starter in size S0, supplied as a pre-assembled unit containing the 3RT2027-1BB40 contactor and the 3RA2921-1BA00 link module with a thermal bimetallic overload relay. This is not a loose-parts kit — the contactor and overload are mechanically and electrically integrated at the factory, so the panel builder receives a single order code that mounts and wires as one device. The coil draw is compatible with standard 24 VDC or 24 VAC outputs from a programmable controller or relay interface. ## Panel fit and mounting constraints The starter measures 45 mm wide × 193.1 mm high × 107 mm deep. The 45 mm width matches the standard S0 feeder size and occupies a single 9 mm DIN-rail module slot plus clearance — the side clearance is listed at 9 mm. Mounting must be vertical; the device is not rated for horizontal or inverted orientation. Clearance requirements: 30 mm upwards, 10 mm forwards, 10 mm downwards, 0 mm backwards. This means the starter can sit flush against a rear panel wall, but needs 30 mm of free air above it for heat dissipation from the bimetallic overload. The pollution degree 3 rating confirms suitability for industrial enclosures where conductive dust or occasional condensation is present. For a panel near a hot process line or in an unheated warehouse, the -20 °C floor is the hard limit — below that the bimetallic element's trip curve shifts outside the CLASS 10 window. The 3RA2125-4CA27-0BB4 carries the SIRIUS brand and is designed to IEC/EN 60947-4-1 for motor starters. Compliance documentation (RoHS, REACH, CE, UKCA, and the declaration of conformity) is available from Siemens upon request. The pollution degree 3 and the thermal overload design mean the starter meets the functional-safety requirements for standard motor protection without a separate overload relay purchase.","metaTitle":"Siemens 3RA2125-4CA27-0BB4 SIRIUS Motor Starter","metaDescription":"Siemens 3RA2125-4CA27-0BB4 SIRIUS non-fused motor starter, size S0, 11 kW at 400 V AC-3, CLASS 10 thermal overload, 24 V coil.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Motor Starters"],"specifications":{"Depth":"107 mm","Width":"45 mm","title":"3RA2125-4CA27-0BB4","Height":"193.1 mm","Upwards":"30 mm","Forwards":"10 mm","Backwards":"0 mm","Downwards":"10 mm","Trip Class":"CLASS 10","At The Side":"9 mm","Rated Value":"24 V","description":"FUSELESS MOTOR STARTER DIRECT START 600V AC SZ S0 17-22A 24V DC SCREW CONNECTION FOR SCREW MOUNTING OR 35 MM RAIL-MOUNTING TYPE OF COORDINATION 2 IQ = 50 KA ALSO FULFILLS TYPE OF COORDINATION 1 1NO+1NC (MSP) 1NO+1NC (CONTACTOR)","During Storage":"-50 ... +80 °C","lifecycle_stage":"current","During Operation":"-20 ... +60 °C","During Transport":"-55 ... +80 °C","Fastening Method":"Snap-mounted to DIN rail or screw-mounted with additional push-in lug","Mounting Position":"vertical","Product Brand Name":"SIRIUS","Type Of Assignment":"2","Degree Of Pollution":"3","Product Designation":"non-fused motor starter 3RA2","Size Of Load Feeder":"S0","at 230 V rated value":"3 hp","at 400 V rated value":"11 000 W","at 480 V rated value":"22 A","at 500 V rated value":"11 000 W","at 600 V rated value":"21.9 A","Design Of The Product":"direct starter","at 110/120 V rated value":"1.5 hp","at 200/208 V rated value":"5 hp","at 220/230 V rated value":"7.5 hp","at 460/480 V rated value":"15 hp","at 575/600 V rated value":"20 hp","Of The Supplied Contactor":"3RT2027-1BB40","For Main Contacts Stranded":"1 ... 10 mm², 2x (2.5 ... 6 mm²)","Of The Supplied Link Module":"3RA2921-1BA00","Size Of The Circuit-Breaker":"S0","at AC-3 rated value maximum":"690 V","Design Of The Overload Release":"thermal (bimetallic)","Design Of The Switching Contact":"electromechanical","Operating Frequency Rated Value":"50 ... 60 Hz","at AWG cables for main contacts":"2x (16 ... 12), 2x (14 ... 8)","Design Of The Short-Circuit Trip":"magnetic","Of The Supplied Circuit-Breakers":"3RV2021-4CA15","Product Extension Auxiliary Switch":"Yes","holding power of magnet coil at DC":"5.9 W","Surge Voltage Resistance Rated Value":"6 kV","Number Of Poles For Main Current Circuit":"3","Product Function Short Circuit Protection":"Yes","number of NC contacts for auxiliary contacts":"2","number of NO contacts for auxiliary contacts":"2","shock resistance according to IEC 60068-2-27":"6g / 11 ms","at 400 V according to IEC 60947-4-1 rated value":"153 000 A","at 500 V according to IEC 60947-4-1 rated value":"100 000 A","operational current at AC-3 at 400 V rated value":"22 A","Type Of Electrical Connection For Main Current Circuit":"screw-type terminals","Mechanical Service Life (Switching 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":"17 ... 22 A","Connectable Conductor Cross-Section For Main Contacts Finely Stranded With Core End Processing":"1 ... 6 mm²"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/f84753078485e9fc6688a5e7a31f49f3.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=319182&mlfb=3RA2125-4CA27-0BB4"},"ai":{"faq":[{"question":"What is the trip class and what does it mean for motor protection?","answer":"This is the standard trip class for general-purpose squirrel-cage motors — fast enough to protect against locked-rotor heating while allowing normal starting inrush on pumps, fans, and compressors."},{"question":"What are the power ratings at common voltages?","answer":"At 400 V AC-3 the starter is rated 11 kW; at 480 V it carries 22 A; at 460/480 V it is rated 15 hp; at 575/600 V it is rated 20 hp. The maximum switching voltage is 690 V AC-3."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RA2125-4CA27-0BB4","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/3RA2125-4CA27-0BB4 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}}