{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RT1025-1KB40","brand":"Siemens","brandSlug":"siemens","productSlug":"3RT1025-1KB40","canonicalUrl":"https://aoctrl.com/siemens/3RT1025-1KB40","factsUrl":"https://aoctrl.com/api/mcp/products/3RT1025-1KB40","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS power contactor, size S0, 3RT1025-1KB40, 24 VDC coil, screw terminals, 7.5 kW at AC-2 400 V, snap-on DIN rail mounting.","salesMarkdown":"It is a current-production part, so it remains a standard BOM line item for new builds and replacements alike. The built-in varistor surge suppressor protects the coil driver from inductive kickback, so you can skip adding an external flyback diode across the coil terminals. Rated for AC-2 duty at 7.5 kW on 400 V, this contactor handles slip-ring motor starting and reversing loads where the current stays below the make/break stress of AC-3. For plugging or inching duty, the AC-4 rating of 15.5 A at 400 V gives the thermal limit for frequent reversals. The 45 mm width and 88 mm height fit the S0 footprint, which is the standard for contactors up to about 12 A AC-3. IP20 on the front enclosure protects against finger contact inside the panel; the terminal area is IP00, meaning the wiring compartment is open to the panel environment. This is typical for panel-mounted contactors — the enclosure itself provides the final IP rating. Main circuit terminals accept screw-clamp connections: 2x 0.5–1.5 mm² solid, 2x 0.75–2.5 mm² solid, or up to 2x 4 mm² solid. The auxiliary/control circuit terminals handle 2x 1–2.5 mm² solid or stranded, up to 2x 6 mm². AWG equivalents are listed for both circuits — main terminals take 2x 16–12 AWG, aux terminals take 2x 20–14 AWG. For Type 1 coordination (welding allowed but no fire risk), use a 63 A gL/gG fuse. These values let you size the branch circuit protection without guesswork. For a contactor switching once per minute, that's roughly 19 years of continuous service before mechanical wear-out.","metaTitle":"Siemens SIRIUS 3RT1025-1KB40 Power Contactor, S0, 24 VDC, 7.","metaDescription":"Siemens SIRIUS 3RT1025-1KB40 power contactor, size S0, 24 VDC coil, rated 7.5 kW at AC-2 400 V. Current production. Screw terminals, snap-on DIN rail. Sourced to order against RFQ.","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","Rated Value":"24 V","On The Front":"IP20","Initial Value":"0.7","Of The Terminal":"IP00","lifecycle_stage":"current","During Operation":"-25 ... +60 °C","Fastening Method":"screw and snap-on mounting onto 35 mm standard mounting rail according to DIN EN 50022","Full-Scale Value":"1.25","Size Of Contactor":"S0","Solid Or Stranded":"2x (1 ... 2,5 mm²), 2x (2,5 ... 6 mm²), max. 2x 10 mm²","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","Side-By-Side Mounting":"Yes","For Main Current Circuit":"screw-type terminals","at AC-2 at 400 V rated value":"7.5 kW","at AC-4 at 400 V rated value":"15.5 A","Substance Prohibitance (Date)":"01.07.2006 00:00:00","Design Of The Surge Suppressor":"with varistor","at AWG cables for main contacts":"2x (16 ... 12), 2x (14 ... 10), 1x 8","For Auxiliary And Control Circuit":"screw-type terminals","With Type Of Assignment 2 Required":"fuse gL/gG: 25 A","closing power of magnet coil at DC":"4.2 W","holding power of magnet coil at DC":"4.2 W","reference code acc. to IEC 81346-2":"Q","With Type Of Coordination 1 Required":"fuse gL/gG: 63 A","at AWG cables for auxiliary contacts":"2x (20 ... 16), 2x (18 ... 14), 1x 12","operational current at AC-12 maximum":"10 A","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","Contact Reliability Of Auxiliary Contacts":"1 faulty switching per 100 million (17 V, 1 mA)","Type Of Voltage Of The Control Supply Voltage":"DC","Required Spacing For Grounded Parts At The Side":"6 mm","Installation Altitude At Height Above Sea Level Maximum":"2 000 m","For Short-Circuit Protection Of The Auxiliary Switch Required":"fuse gL/gG: 10 A","number of NC contacts for auxiliary contacts instantaneous contact":"0","number of NO contacts for auxiliary contacts instantaneous contact":"0"}},"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=248685&mlfb=3RT1025-1KB40","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RT1025-1KB40/alternatives.json"},"ai":{"faq":[{"question":"What is the depth of this contactor?","answer":"The depth is 101 mm. This dimension, combined with the 45 mm width and 88 mm height, defines the S0 frame envelope for panel layout."},{"question":"What wire sizes does the main circuit accept?","answer":"The main screw terminals accept 2x 0.5–1.5 mm² solid, 2x 0.75–2.5 mm² solid, or up to 2x 4 mm² solid. In AWG, that is 2x 16–12, 2x 14–10, or 1x 8."},{"question":"What compliance documentation is available for this part?","answer":"The part carries a RoHS compliance date of July 1, 2006, covering the original EU RoHS directive. The SIRIUS series typically provides CE, UL, and CSA certifications; specific declarations are available through the manufacturer's documentation portal."},{"question":"Will 3RT1025-1KB40 drop into a panel specified for 3RT1015-1BB42?","answer":"Both are S0 frame contactors with the same 45 mm width and DIN rail mounting, so the physical footprint is identical. However, the 3RT1015-1BB42 uses a 24 VAC coil, while this part uses 24 VDC — the coil driver must match the DC requirement. The terminal layout and auxiliary contact positions are the same within the S0 family."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RT1025-1KB40","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 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}}