{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RT1025-1KB40-1AA0","brand":"Siemens","brandSlug":"siemens","productSlug":"3RT1025-1KB40-1AA0","canonicalUrl":"https://aoctrl.com/siemens/3RT1025-1KB40-1AA0","factsUrl":"https://aoctrl.com/api/mcp/products/3RT1025-1KB40-1AA0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RT1025-1KB40-1AA0, power contactor, size S0, 24 V DC coil, screw-type terminals, IP20 front, side-by-side mountable.","salesMarkdown":"## Siemens SIRIUS 3RT1025-1KB40-1AA0 — 24 VDC Power Contactor, Size S0 The terminal area itself is IP00, as expected for screw-clamp connections inside a closed cabinet. ## Coil and Switching Performance The 24 V DC coil picks up at 0.7 times the rated voltage (about 16.8 V) and drops out at 1.25 times (30 V), so it holds in during brownout conditions down to roughly 70 % of nominal. Closing and holding power are both 4.2 W DC — a steady-state draw that a 24 VDC power supply can handle without oversizing. The built-in varistor surge suppressor clips the inductive kickback from the coil, which saves you from having to add an external flyback diode across the coil terminals. ## Motor Ratings and Duty Cycles For motor switching, the key numbers are the AC-3 and AC-4 ratings. At 400 V AC, the contactor is rated 7.5 kW in AC-3 duty (starting and stopping a running motor) and 15.5 A in AC-4 duty (plugging or inching). At 690 V, it handles 11 kW in AC-3. The AC-1 resistive rating at 400 V is 3 A. These figures tell you the contactor is sized for a 7.5 kW motor at 400 V under normal starting, and it can handle the higher thermal stress of reversing or jogging at 15.5 A. Main terminals accept solid conductors from 2x 0.5 to 2x 4 mm² and stranded from 2x 1 to 2x 10 mm². That covers most panel wiring from 18 AWG to 8 AWG.","metaTitle":"Siemens 3RT1025-1KB40-1AA0 SIRIUS Power Contactor, 24 VDC Co","metaDescription":"Siemens SIRIUS 3RT1025-1KB40-1AA0 power contactor, size S0, 24 VDC coil, screw terminals, IP20 front. Current lifecycle. Sourced to order. Request a quote.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Contactors"],"specifications":{"Depth":"101 mm","Solid":"2x (0.5 ... 1.5 mm²), 2x (0.75 ... 2.5 mm²), max. 2x (0.75 ... 4 mm²)","Width":"45 mm","Height":"88 mm","Maximum":"2 000 m","At The Side":"6 mm","Rated Value":"24 V","On The Front":"IP20","Initial Value":"0.7","Mounting type":"screw and snap-on mounting onto 35 mm standard mounting rail according to DIN EN 50022","Of The Terminal":"IP00","lifecycle_stage":"current","During Operation":"-25 ... +60 °C","Full-scale value":"1.25","Size of contactor":"S0","Product brand name":"SIRIUS","Degree of pollution":"3","Product designation":"power contactor","at 24 V rated value":"10 A","at 60 V rated value":"2 A","Of Contactor Typical":"10 000 000","at 110 V rated value":"1 A","at 220 V rated value":"0.3 A","at 230 V rated value":"6 A","at 400 V rated value":"3 A","at 500 V rated value":"10 kW","at 690 V rated value":"11 kW","Instantaneous Contact":"0","Side-by-side mounting":"Yes","For Main Current Circuit":"screw-type terminals","Single Or Multi-Stranded":"2x (1 ... 2,5 mm²), 2x (2,5 ... 6 mm²), max. 2x 10 mm²","at AC-2 at 400 V rated value":"7.5 kW","at AC-4 at 400 V rated value":"15.5 A","Design of the surge suppressor":"with varistor","Closing power of magnet coil at DC":"4.2 W","Holding power of magnet coil at DC":"4.2 W","Operating current at AC-12 maximum":"10 A","With Type Of Assignment 2 Required":"fuse gL/gG: 25 A","at AWG conductors for main contacts":"2x (16 ... 12), 2x (14 ... 10), 1x 8","With Type Of Coordination 1 Required":"fuse gL/gG: 63 A","Reference code acc. to DIN EN 81346-2":"Q","Number of NC contacts for main contacts":"0","Number of NO contacts for main contacts":"3","Finely Stranded With Core End Processing":"2x (0.5 ... 1.5 mm²), 2x (0.75 ... 2.5 mm²)","Number of poles for main current circuit":"3","at AWG conductors for auxiliary contacts":"2x (20 ... 16), 2x (18 ... 14), 1x 12","Contact reliability of auxiliary contacts":"1 faulty switching per 100 million (17 V, 1 mA)","For Auxiliary And Control Current Circuit":"screw-type terminals","at ambient temperature 40 °C rated value":"40 A","Type of voltage of the control supply voltage":"DC","For Short-Circuit Protection Of The Auxiliary Switch Required":"fuse gL/gG: 10 A"}},"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=459300&mlfb=3RT1025-1KB40-1AA0","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RT1025-1KB40-1AA0/alternatives.json"},"ai":{"faq":[{"question":"Where can I buy 3RT1025-1KB40-1AA0 and get a price?","answer":"This part is sourced and quoted to order through independent distribution. Submit an RFQ; availability and current pricing are confirmed at quote time."},{"question":"What wire sizes fit the main terminals?","answer":"Solid conductors: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), max 2x (0.75 to 4 mm²). Stranded: 2x (1 to 2.5 mm²), 2x (2.5 to 6 mm²), max 2x 10 mm². AWG equivalents: 2x (16 to 12), 2x (14 to 10), 1x 8."},{"question":"What is the depth of 3RT1025-1KB40-1AA0?","answer":"The depth is 101 mm. Width is 45 mm, height is 88 mm."},{"question":"Will 3RT1025-1KB40-1AA0 drop into a panel specified around 3RT1023-1AL20?","answer":"Both are size S0 contactors on the same 45 mm footprint with screw terminals and 24 V DC coils, so the mechanical fit and wiring are identical. The difference is in the motor ratings: the 3RT1025-1KB40-1AA0 carries higher AC-3 power (7.5 kW vs lower at 400 V) and a different built-in surge suppressor (varistor vs RC). Check the motor kW against your load before swapping."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RT1025-1KB40-1AA0","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/3RT1025-1KB40-1AA0 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}}