{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RA2125-4BA26-0BB4","brand":"Siemens","brandSlug":"siemens","productSlug":"3RA2125-4BA26-0BB4","canonicalUrl":"https://aoctrl.com/siemens/3RA2125-4BA26-0BB4","factsUrl":"https://aoctrl.com/api/mcp/products/3RA2125-4BA26-0BB4","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RA2125-4BA26-0BB4 non-fused motor starter, Size S0, direct starter, Class 10 thermal overload, 24 V DC coil, 7.5 kW at 400 V AC-3, 50/60 Hz, DIN rail mount.","salesMarkdown":"## Size S0 direct starter with Class 10 thermal protection The 3RA2125-4BA26-0BB4 is a SIRIUS non-fused motor starter, Size S0, configured as a direct starter — meaning the contactor and overload relay are integrated into a single assembly that snaps onto DIN rail or screws in with the included push-in lug. The supplied contactor is a 3RT2026-1BB40, paired with a 3RA2921-1BA00 link module — the assembly is factory-tested as a coordinated starter, so you don't need to match contactor and overload separately. ## Motor power ratings across common line voltages At 400 V AC-3 duty, this starter is rated for 7.5 kW (about 15.2 A at 480 V, 17.8 A at 600 V) — the magnetic short-circuit trip handles fault clearing, while the thermal bimetallic element provides overload protection. The maximum AC-3 rated voltage is 690 V, and the operating frequency covers 50 to 60 Hz — suitable for both IEC and NEMA motor nameplate ratings. ## Mounting clearances and environmental limits Dimensions are 107 mm deep, 45 mm wide, and 193.1 mm tall — the S0 frame size fits standard 45 mm-wide DIN rail slots. Required clearances: 30 mm upwards, 10 mm forwards, 10 mm downwards, 9 mm at the sides, and 0 mm backwards. Mounting position is vertical only — the thermal overload calibration assumes vertical orientation; horizontal mounting shifts the trip curve. ## Active production — sourced per RFQ The Type of Assignment 2 rating means the starter coordinates with a downstream circuit breaker for Type 2 coordination — the starter withstands fault current without welding the contacts, per IEC 60947-4-1.","metaTitle":"Siemens 3RA2125-4BA26-0BB4 SIRIUS Motor Starter, Size S0","metaDescription":"Siemens 3RA2125-4BA26-0BB4 SIRIUS non-fused motor starter, Size S0, Class 10 thermal protection, 24 VDC coil, 7.5 kW at 400 V.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Motor Starters"],"specifications":{"Depth":"107 mm","Width":"45 mm","title":"3RA2125-4BA26-0BB4","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 14-20A 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":"7 500 W","at 480 V rated value":"15.2 A","at 500 V rated value":"11 000 W","at 600 V rated value":"17.8 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":"5 hp","at 460/480 V rated value":"10 hp","at 575/600 V rated value":"15 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","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":"3RV2021-4BA15","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","operational current at AC-3 at 400 V rated value":"15.5 A","Type Of Electrical Connection For Main Current Circuit":"screw-type terminals","Mechanical Service Life (Operating Cycles) Of Contactor Typical":"10 000 000","Response Value Current Of Instantaneous Short-Circuit Trip Unit":"260 A","insulation voltage with degree of pollution 3 at AC rated value":"690 V","Type Of Connectable Conductor Cross-Sections For Main Contacts Stranded":"1 ... 10 mm², 2x (2.5 ... 6 mm²)","Adjustable Current Response Value Current Of The Current-Dependent Overload Release":"14 ... 20 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/724c6b97065ba8a40a2c89fe2c72b8b6.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=396900&mlfb=3RA2125-4BA26-0BB4"},"ai":{"faq":[{"question":"What are the key motor power ratings for the 3RA2125-4BA26-0BB4?","answer":"At 400 V AC-3 it's rated 7.5 kW; at 480 V it draws 15.2 A; at 600 V it draws 17.8 A. The coil is 24 V DC."},{"question":"What clearance is needed around the 3RA2125-4BA26-0BB4 in a panel?","answer":"Allow 30 mm above, 10 mm in front, 10 mm below, 9 mm at the sides, and 0 mm behind the unit. The S0 frame is 45 mm wide, 107 mm deep, and 193.1 mm tall."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RA2125-4BA26-0BB4","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/3RA2125-4BA26-0BB4 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}}