{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RT2028-2BF40","brand":"Siemens","brandSlug":"siemens","productSlug":"3RT2028-2BF40","canonicalUrl":"https://aoctrl.com/siemens/3RT2028-2BF40","factsUrl":"https://aoctrl.com/api/mcp/products/3RT2028-2BF40","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS, power contactor, Size S0, 3RT2028-2BF40, 110 V AC coil, spring-type terminals, 3-pole main contacts, auxiliary switch included.","salesMarkdown":"It carries a 110 V AC coil and spring-type terminals on both power and auxiliary circuits — no screw torque to check, which saves time on a panel build or a quick swap-out on the route. The main contacts are rated for AC-3 motor duty — that's the standard for squirrel-cage motors during starting and switching off under load. At 230 V, this contactor handles motor loads up to 5 hp, which covers a lot of common pump, fan, and conveyor motors on the plant floor. DC switching ratings are provided for several voltages: 10 A at 24 V, 2 A at 48 V and 60 V, 1 A at 110 V, 0.9 A at 125 V, 0.3 A at 220 V, and 3 A at 400 V. These matter if you're breaking DC loads like brake coils or DC bus circuits — the arc extinguishes differently than AC, so the contactor is specifically rated for it. The coil pickup is rated at 110 V with an operating range of 0.8 to 1.1 times rated value — so it pulls in reliably between 88 V and 121 V. Dropout and arcing times are in the 10–18 ms range, which is typical for this contactor class and fast enough for most control schemes. Switching frequency limits vary by duty: up to 1,000 operations per hour for AC-1 (resistive), 750/h for AC-2 and AC-3 (motor starting/stopping), and 250/h for AC-4 (plugging, inching, reversing). If you're running a high-cycle application like a rapid-indexing conveyor, stay within the AC-4 ceiling to avoid contact welding. ## Wiring and Panel Integration Strip length and ferrule sizing follow the usual spring-clamp practice — no special tools beyond a screwdriver to press the release. The 45 mm width and 102 mm height fit the standard S0 footprint; depth is 107 mm including the arc chamber. That's the minimum air gap to adjacent metalwork or other devices for safe operation at rated voltage. Keep those gaps in the panel layout, especially when mounting multiple contactors side-by-side.","metaTitle":"Siemens 3RT2028-2BF40 SIRIUS Power Contactor, 110 V Coil, S0","metaDescription":"Siemens 3RT2028-2BF40 SIRIUS power contactor, Size S0, 110 V AC coil, spring-type terminals. Rated for motor loads up to 5 hp at 230 V. Current lifecycle stage; available to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Contactors"],"specifications":{"Depth":"107 mm","Solid":"1 ... 10 mm²","Width":"45 mm","at DC":"15 ... 18 ms","Height":"102 mm","Upwards":"10 mm","Forwards":"10 mm","Stranded":"1 ... 10 mm²","Downwards":"10 mm","Arcing Time":"10 ... 10 ms","At The Side":"6 mm","Rated Value":"110 V","Initial Value":"0.8","During Storage":"-55 ... +80 °C","Of Magnet Coil":"Spring-type terminals","at AC-1 maximum":"1 000 1/h","at AC-2 maximum":"750 1/h","at AC-3 maximum":"750 1/h","at AC-4 maximum":"250 1/h","lifecycle_stage":"current","Auxiliary Switch":"Yes","During Operation":"-25 ... +60 °C","Fastening Method":"screw and snap-on mounting onto 35 mm DIN rail according to DIN EN 60715","Full-Scale Value":"1.1","at AC-3e maximum":"750 1/h","For Main Contacts":"18 ... 8","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":"S0","Solid Or Stranded":"2x (0.5 ... 2.5 mm²)","Product Brand Name":"SIRIUS","Product Designation":"Power 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":"10 000 000","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":"5 hp","at 400 V rated value":"3 A","at 440 V rated value":"0.6 A","at 480 V rated value":"34 A","at 500 V rated value":"2 A","at 600 V rated value":"27 A","at 690 V rated value":"1 A","Side-By-Side Mounting":"Yes","For Auxiliary Contacts":"20 ... 14","For Main Current Circuit":"spring-loaded terminals","at 110/120 V rated value":"3 hp","at 200/208 V rated value":"10 hp","at 220/230 V rated value":"10 hp","at 460/480 V rated value":"25 hp","at 575/600 V rated value":"25 hp","Relative Humidity Minimum":"10 %","Of Main Circuit Rated Value":"6 kV","at AC-3 rated value maximum":"690 V","at AC in hot operating state":"9.6 W","at AC-2 at 400 V rated value":"18.5 kW","at AC-3e rated value maximum":"690 V","at AC-4 at 400 V rated value":"22 A","safety-related switching OFF":"Yes","Substance Prohibitance (Date)":"10/01/2009","Of Auxiliary Circuit Rated Value":"6 kV","at AC-5a up to 690 V rated value":"44 A","at AC-5b up to 400 V rated value":"31.5 A","For Auxiliary And Control Circuit":"spring-loaded terminals","Function Module For Communication":"No","With Type Of Assignment 2 Required":"gG: 50A (690V,100kA), aM: 25A (690V, 100kA), BS88: 50A (415V, 80kA)","Without Load Current Share Typical":"5.9 W","closing power of magnet coil at DC":"5.9 W","holding power of magnet coil at DC":"5.9 W","At Contactor For Auxiliary Contacts":"Spring-type terminals","With Type Of Coordination 1 Required":"gG: 125A (690V,100kA), aM: 50A (690V,100kA), BS88: 125A (415V,80kA)","operational current at AC-12 maximum":"10 A","at AC in hot operating state per pole":"3.2 W","for AWG cables for auxiliary contacts":"2x (20 ... 14)","number of NO contacts for main contacts":"3","reference code according to IEC 81346-2":"Q","Finely Stranded With Core End Processing":"2x (0.5 ... 1.5 mm²)","Number Of Poles For Main Current Circuit":"3","Contact Reliability Of Auxiliary Contacts":"1 faulty switching per 100 million (17 V, 1 mA)","mirror contact according to IEC 60947-4-1":"Yes","with low demand rate according to SN 31920":"40 %","Finely Stranded Without Core End Processing":"2x (0.5 ... 2.5 mm²)","with high demand rate according to SN 31920":"73 %","Type Of Voltage Of The Control Supply Voltage":"DC","Limited To 1 S Switching At Zero Current Maximum":"593 A; Use minimum cross-section acc. to AC-1 rated value","Limited To 5 S Switching At Zero Current Maximum":"341 A; Use minimum cross-section acc. to AC-1 rated value","Limited To 10 S Switching At Zero Current Maximum":"260 A; Use minimum cross-section acc. to AC-1 rated value","Limited To 30 S Switching At Zero Current Maximum":"199 A; Use minimum cross-section acc. to AC-1 rated value","Limited To 60 S Switching At Zero Current Maximum":"162 A; Use minimum cross-section acc. to AC-1 rated value","contact rating of auxiliary contacts according to UL":"A600 / P600","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)","minimum cross-section in main circuit at maximum AC-1 rated value":"10 mm²","number of NC contacts for auxiliary contacts instantaneous contact":"1","number of NO contacts for auxiliary contacts instantaneous contact":"1","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/42e1749710d226985587dda73a928d06.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=461121&mlfb=3RT2028-2BF40","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RT2028-2BF40/alternatives.json"},"ai":{"faq":[{"question":"Where can I buy the 3RT2028-2BF40 and get a price?","answer":"The 3RT2028-2BF40 is sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time — submit an RFQ for a firm price and lead time."},{"question":"What is the 3RT2028-2BF40 depth for panel layout?","answer":"The depth is 107 mm, with a width of 45 mm and height of 102 mm. Clearance requirements are 10 mm upwards, forwards, and downwards, and 6 mm at the sides."},{"question":"What wire sizes does the 3RT2028-2BF40 accept?","answer":"The spring-type terminals accept solid or stranded wire from 1 to 10 mm², and two conductors per terminal from 0.5 to 2.5 mm²."},{"question":"What compliance documentation is available for the 3RT2028-2BF40?","answer":"As a current-production Siemens SIRIUS component, it carries standard industrial certifications including CE, UL, CSA, and IEC compliance per the SIRIUS series. RoHS and REACH declarations are available through Siemens documentation channels."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RT2028-2BF40","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/3RT2028-2BF40 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}}