{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RA2125-1KD24-0BB4","brand":"Siemens","brandSlug":"siemens","productSlug":"3RA2125-1KD24-0BB4","canonicalUrl":"https://aoctrl.com/siemens/3RA2125-1KD24-0BB4","factsUrl":"https://aoctrl.com/api/mcp/products/3RA2125-1KD24-0BB4","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RA2125-1KD24-0BB4, non-fused motor starter, size S0, direct starter, 24 V DC coil, Trip Class 10, snaps onto 60 mm busbar systems.","salesMarkdown":"The Siemens 3RA2125-1KD24-0BB4 is a SIRIUS non-fused motor starter — a pre-assembled combination of a contactor and a thermal bimetallic overload relay in a single S0 frame. It is a direct starter, meaning it applies full line voltage to the motor on start, and is rated for AC-3 switching duty up to 690 V. The 24 V DC coil is held in by the control supply; the bimetallic overload provides adjustable trip protection with Trip Class 10 response, so it clears a stalled rotor fast enough for standard induction motors on conveyors, pumps, and fans. This unit snaps directly onto a 60 mm busbar system (the supplied busbar adapter 8US1251-5NT10 is included). Mounting position is vertical; the S0 footprint occupies 45 mm width, 260 mm height, and 165 mm depth. Clearance requirements: 30 mm upwards, 10 mm forwards, 10 mm downwards, 9 mm at the side, and 0 mm backwards — so it can sit flush against a back panel. The supplied contactor is 3RT2024-1BB40 and the link module is 3RA2921-1BA00, meaning the assembly arrives as a single orderable unit ready for panel wiring. The AC-3 motor ratings tell you the real-world switching capacity across common supply voltages. At 400 V it handles 5 500 W (roughly 7.5 hp); at 460/480 V it is rated for 7.5 hp; at 575/600 V it reaches 10 hp. The same unit at 230 V is rated 2 hp.","metaTitle":"Siemens 3RA2125-1KD24-0BB4 SIRIUS non-fused motor starter","metaDescription":"Siemens 3RA2125-1KD24-0BB4 SIRIUS non-fused motor starter, size S0, 24V DC coil, Trip Class 10, snaps onto 60mm busbar. Sourced to order. Request a quote.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Motor Starters"],"specifications":{"Depth":"165 mm","Width":"45 mm","Height":"260 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","During Storage":"-50 ... +80 °C","lifecycle_stage":"current","During Operation":"-20 ... +60 °C","During Transport":"-55 ... +80 °C","Fastening Method":"for snapping onto 60 mm busbar systems","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":"2 hp","at 400 V rated value":"5 500 W","at 480 V rated value":"11 A","at 500 V rated value":"7 500 W","at 600 V rated value":"11 A","Design Of The Product":"direct starter","at 110/120 V rated value":"0.5 hp","at 200/208 V rated value":"3 hp","at 220/230 V rated value":"3 hp","at 460/480 V rated value":"7.5 hp","at 575/600 V rated value":"10 hp","Of The Supplied Contactor":"3RT2024-1BB40","For Main Contacts Stranded":"1 ... 10 mm², 2x (2.5 ... 6 mm²)","Of The Supplied Link Module":"3RA2921-1BA00","Size Of The Circuit-Breaker":"S00","at AC-3 rated value maximum":"690 V","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","at AWG cables for main contacts":"2x (16 ... 12), 2x (14 ... 8)","Design Of The Short-Circuit Trip":"magnetic","Of The Supplied Circuit-Breakers":"3RV2011-1KA15","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":"11.5 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":"162.5 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":"9 ... 12.5 A","Connectable Conductor Cross-Section For Main Contacts Finely Stranded With Core End Processing":"1 ... 6 mm²"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":null,"sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=78079&mlfb=3RA2125-1KD24-0BB4","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RA2125-1KD24-0BB4/alternatives.json"},"ai":{"faq":[{"question":"What is the difference between 3RA2125-1KD24-0BB4 and 3RA2120-1KD24-0BB4?","answer":"The 3RA2125 series is the non-fused motor starter; the 3RA2120 series is the fused version. The 3RA2125-1KD24-0BB4 includes a busbar adapter (8US1251-5NT10) for snapping onto 60 mm busbar systems, while the fused variant requires separate fuse holders. Both share the same S0 frame, 24 V DC coil, and Trip Class 10 overload."},{"question":"Is 3RA2125-1KD24-0BB4 suitable for 60 mm busbar systems?","answer":"Yes, it is designed for snapping onto 60 mm busbar systems and ships with the busbar adapter 8US1251-5NT10 included."},{"question":"What is Type 2 coordination for motor starters?","answer":"Type 2 coordination means that under a short-circuit fault up to the rated prospective current, the motor starter will not suffer damage that prevents further operation — no welding of contacts or destruction of the overload relay. This starter is designed for Type 2 coordination (type of assignment 2)."},{"question":"Where can I buy 3RA2125-1KD24-0BB4 available via RFQ confirmation?","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/3RA2125-1KD24-0BB4","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/3RA2125-1KD24-0BB4 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}}