{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RT2018-4KB42-0LA0","brand":"Siemens","brandSlug":"siemens","productSlug":"3RT2018-4KB42-0LA0","canonicalUrl":"https://aoctrl.com/siemens/3RT2018-4KB42-0LA0","factsUrl":"https://aoctrl.com/api/mcp/products/3RT2018-4KB42-0LA0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS contactor, Size S00, 3RT2018-4KB42-0LA0, 24 VDC coil with ring cable lug, extended operating range, screw and snap-on DIN rail mount.","salesMarkdown":"It has an extended operating range with a pickup threshold of 0.7 times rated value. Physically it's compact: 45 mm wide, 61 mm tall, 117 mm deep. That puts it in the standard S00 footprint that fits tightly packed DIN-rail enclosures. Mounting is via screw or snap-on onto 35 mm rail per DIN EN 60715, and side-by-side mounting is allowed with the specified clearances — 10 mm upward, 10 mm forward, 10 mm downward, 6 mm at the side. ## What the DC switching ratings mean for your load This contactor carries a full set of DC-1 / DC-13 style switching ratings across the voltage range, and the values tell you exactly what it can break without welding contacts. At 24 V DC it's rated 10 A — that's the sweet spot for most control and small DC motor loads. At 48 V and 60 V it drops to 2 A, at 110 V to 1 A, at 220 V to 0.3 A, and at 690 V to 1 A. The 480 V and 600 V entries (14 A and 11 A respectively) look like AC ratings — likely AC-3 motor duty — so don't confuse those with DC interrupt capability at those voltages. That's fast enough for most interlocking and sequencing circuits, but if you're paralleling contacts for higher DC current, account for the total arcing energy across the gap. The auxiliary switch is integrated (yes), so there's no separate add-on block to order for basic status feedback. The coil connection uses a ring cable lug. The main power terminals accept solid conductors: 2x 0.5 to 1.5 mm², 2x 0.75 to 2.5 mm², or 2x 4 mm². That helps when you're fitting it into a crowded panel or a non-standard orientation.","metaTitle":"Siemens SIRIUS 3RT2018-4KB42-0LA0 Contactor, Size S00, 24 VD","metaDescription":"Siemens SIRIUS 3RT2018-4KB42-0LA0 contactor, Size S00, 24 VDC coil, extended operating range, screw and snap-on DIN rail mount. Current production. Sourced to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Contactors"],"specifications":{"Depth":"117 mm","Solid":"2x (0.5 ... 1.5 mm²), 2x (0.75 ... 2.5 mm²), 2x 4 mm²","Width":"45 mm","at DC":"7 ... 20 ms","Height":"61 mm","Upwards":"10 mm","Forwards":"10 mm","Downwards":"10 mm","Arcing Time":"10 ... 15 ms","At The Side":"6 mm","Rated Value":"24 V","Initial Value":"0.7","During Storage":"-55 ... +80 °C","Of Magnet Coil":"Ring cable lug connection","Type Of Voltage":"DC","at AC-4 maximum":"250 1/h","lifecycle_stage":"current","Auxiliary Switch":"Yes","During Operation":"-40 ... +70 °C","Fastening Method":"screw and snap-on mounting onto 35 mm standard mounting rail according to DIN EN 60715","Full-Scale Value":"1.25","Mounting Position":"+/-180° rotation possible on vertical mounting surface; can be tilted forward and backward by +/- 22.5° on vertical mounting surface","Size Of Contactor":"S00","Product Brand Name":"SIRIUS","Product Designation":"Contactor","at 24 V rated value":"10 A","at 48 V rated value":"2 A","at 60 V rated value":"2 A","Of Contactor Typical":"30 000 000","at 110 V rated value":"1 A","at 125 V rated value":"0.9 A","at 220 V rated value":"0.3 A","at 230 V rated value":"2 hp","at 400 V rated value":"3 A","at 480 V rated value":"14 A","at 500 V rated value":"2 A","at 600 V rated value":"11 A","at 690 V rated value":"1 A","Design Of The Product":"With extended operating range","Side-By-Side Mounting":"Yes","For Main Current Circuit":"Ring cable lug connection","at 110/120 V rated value":"1 hp","at 200/208 V rated value":"3 hp","at 220/230 V rated value":"5 hp","at 460/480 V rated value":"10 hp","at 575/600 V rated value":"10 hp","at AC-2 at AC-3e maximum":"750 1/h","Relative Humidity Minimum":"10 %","Of Main Circuit Rated Value":"6 kV","at AC-3 rated value maximum":"690 V","at maximum AC-1 rated value":"4 mm²","at AC in hot operating state":"6.6 W","at AC-2 at 400 V rated value":"7.5 kW","at AC-3e rated value maximum":"690 V","at AC-4 at 400 V rated value":"11.5 A","Substance Prohibitance (Date)":"10/01/2009","Design Of The Surge Suppressor":"suppressor diode","Of Auxiliary Circuit Rated Value":"6 kV","For Auxiliary And Control Circuit":"ring terminal lug connection","Function Module For Communication":"No","Product Function Bus Communication":"No","With Type Of Assignment 2 Required":"gG: 25A (690V,100kA), aM: 20A (690V,100kA), BS88: 25A (415V,80kA)","Without Load Current Share Typical":"4 W","closing power of magnet coil at DC":"13 W","holding power of magnet coil at DC":"4 W","At Contactor For Auxiliary Contacts":"Ring cable lug connection","With Type Of Coordination 1 Required":"gG: 50A (690V,100kA), aM: 25A (690V,100kA), BS88: 50A (415V,80kA)","operational current at AC-12 maximum":"10 A","at AC in hot operating state per pole":"2.2 W","number of NO contacts for main contacts":"3","reference code according to IEC 81346-2":"Q","Number Of Poles For Main Current Circuit":"3","Product Function Short Circuit Protection":"No","mirror contact according to IEC 60947-4-1":"Yes","with low demand rate according to SN 31920":"40 %","with high demand rate according to SN 31920":"73 %","number of NC contacts for auxiliary contacts":"1","Type Of Voltage Of The Control Supply Voltage":"DC","Limited To 1 S Switching At Zero Current Maximum":"300 A; Use minimum cross-section acc. to AC-1 rated value","Limited To 5 S Switching At Zero Current Maximum":"169 A; Use minimum cross-section acc. to AC-1 rated value","Limited To 10 S Switching At Zero Current Maximum":"128 A; Use minimum cross-section acc. to AC-1 rated value","Limited To 30 S Switching At Zero Current Maximum":"92 A; Use minimum cross-section acc. to AC-1 rated value","Limited To 60 S Switching At Zero Current Maximum":"74 A; Use minimum cross-section acc. to AC-1 rated value","contact rating of auxiliary contacts according to UL":"A600 / Q600","Of Main Circuit With Degree Of Pollution 3 Rated Value":"690 V","Installation Altitude At Height Above Sea Level Maximum":"2 000 m","Of The Contactor With Added Auxiliary Switch Block Typical":"10 000 000","Of Auxiliary Circuit With Degree Of Pollution 3 Rated Value":"690 V","For Short-Circuit Protection Of The Auxiliary Switch Required":"gG: 10 A (500 V, 1 kA)","Of The Contactor With Added Electronically Optimized Auxiliary Switch Block Typical":"5 000 000"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/4f06d1ea8e07a43e55b02c3b2109507d.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=475144&mlfb=3RT2018-4KB42-0LA0","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RT2018-4KB42-0LA0/alternatives.json"},"ai":{"faq":[{"question":"What are the key dimensions of this contactor?","answer":"Width is 45 mm, height is 61 mm, depth is 117 mm. That's the standard S00 footprint."},{"question":"What wire sizes does the main terminal accept?","answer":"Solid conductors: 2x 0.5 to 1.5 mm², 2x 0.75 to 2.5 mm², or 2x 4 mm²."},{"question":"Will this contactor work in a panel designed for 3RT2026-4BB40?","answer":"No — the 3RT2026-4BB40 is Size S0, which has a different width and mounting footprint. The 3RT2018-4KB42-0LA0 is Size S00. You would need to re-drill the mounting rail or use an adapter plate, and the busbar system would not align."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RT2018-4KB42-0LA0","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/3RT2018-4KB42-0LA0 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}}