{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RA2125-1GH24-0FB4","brand":"Siemens","brandSlug":"siemens","productSlug":"3RA2125-1GH24-0FB4","canonicalUrl":"https://aoctrl.com/siemens/3RA2125-1GH24-0FB4","factsUrl":"https://aoctrl.com/api/mcp/products/3RA2125-1GH24-0FB4","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RA2125-1GH24-0FB4 direct-on-line starter, Size S0, 6.3 A at AC-3 400 V, CLASS 10 trip, 24 V DC coil, spring-loaded terminals, for 60 mm busbar systems.","salesMarkdown":"## Motor starting duty and the AC-3 rating that governs it The 3RA2125-1GH24-0FB4 is a Siemens SIRIUS direct-on-line starter, Size S0, built around the 3RT2024-2FB40 contactor and the 3RA2921-2AA00 link module. ## Panel fit and busbar mounting constraints This starter snaps onto 60 mm busbar systems — the fastening method is integral, not a separate bracket. The mounting position is vertical only; the dimensions are 260 mm high by 45 mm wide by 165 mm deep. Clearance requirements: 50 mm upwards, 20 mm forwards, 10 mm downwards, and 20 mm at the side. Backwards clearance is zero — the unit sits flush against the mounting surface. ## Thermal envelope and storage limits During operation the ambient range is -20 to +60 °C, with temperature compensation active across that band. Storage and transport limits are wider at -50 to +80 °C. The 24 V DC coil (rated value 24... 24 V) draws its holding current through the link module; the supplied contactor is the 3RT2024-2FB40, which carries the same S0 frame size as the circuit-breaker section. The unit holds the line on a motor feeder provided the ambient stays within the operating envelope and the busbar system is rated for the bolted-fault current the upstream breaker can deliver.","metaTitle":"Siemens 3RA2125-1GH24-0FB4 SIRIUS Direct Starter, 6.3 A AC-3","metaDescription":"Siemens 3RA2125-1GH24-0FB4 SIRIUS direct-on-line starter, Size S0, 6.3 A at AC-3 400 V, CLASS 10 trip, 24 V coil, spring terminals.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Motor Starters"],"specifications":{"Depth":"165 mm","Width":"45 mm","title":"3RA2125-1GH24-0FB4","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","description":"Load feeder fuseless, Direct-on-line starting 400 V AC, Size S0 4.50...6.30 A 24 V DC Spring-type terminal for 60 mm busbar systems (also fulfills type of coordination 1) Type of coordination 2, Iq = 150 kA 1 NO+1 NC (contactor) with diode combination plugged in at the front","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":"0.75 hp","at 400 V rated value":"2 200 kW","at 480 V rated value":"6.3 A","at 600 V rated value":"6.3 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":"0.25 hp","at 200/208 V rated value":"1.5 hp","at 220/230 V rated value":"1.5 hp","at 460/480 V rated value":"3 hp","at 575/600 V rated value":"5 hp","Of The Supplied Contactor":"3RT2024-2FB40","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":"6.3 A","at AC-3e rated value maximum":"690 V","at AC-3e at 400 V rated value":"6.3 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":"3RV2021-1GA25","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":"2.7 W","Number Of Poles For Main Current Circuit":"3","Product Function Short Circuit Protection":"Yes","protocol is supported AS-Interface protocol":"No","number of NC contacts for auxiliary contacts":"1","number of NO contacts for auxiliary contacts":"1","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":"82 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":"4.5 ... 6.3 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/691d87764bf2c8ab5345483fea740622.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=552678&mlfb=3RA2125-1GH24-0FB4"},"ai":{"faq":[{"question":"What is 3RA2125-1GH24-0FB4's AC-3 current rating at 400 V?","answer":"This is the motor-switching current that governs the selection — it is lower than the resistive-load rating and is the figure to use when sizing the starter for a three-phase induction motor."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RA2125-1GH24-0FB4","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/3RA2125-1GH24-0FB4 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-07-22T19:47:38.189Z","lastPublished":"2026-07-22T19:47:38.189Z","indexable":true}}