{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RT1045-1AG20","brand":"Siemens","brandSlug":"siemens","productSlug":"3RT1045-1AG20","canonicalUrl":"https://aoctrl.com/siemens/3RT1045-1AG20","factsUrl":"https://aoctrl.com/api/mcp/products/3RT1045-1AG20","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS power contactor, 3RT1045-1AG20, S3 frame, screw-type terminals, 45 kW at 500 V AC-3, 21.1 kW at 690 V, IP20 front, current production.","salesMarkdown":"The 3RT1045-1AG20: Rated at 45 kW at 500 V and 21.1 kW at 690 V in AC-3 duty, this contactor handles the full-load current of a three-phase induction motor within those power bands. The screw-type terminals on the main current circuit accept solid conductors from 0.5 mm² up to 4 mm² (two per clamp) and stranded conductors up to 50 mm², which covers the range from control wiring through to the motor feeder cable for a 45 kW load. ## Environmental and Protection Ratings The front of the contactor carries IP20 protection with the cover or box terminal fitted, meaning it is finger-safe from the front once installed in a panel. The terminal area itself is rated IP00, so the contactor must live inside an enclosure that provides the overall panel ingress rating. ## Switching Performance and Mechanical Life Mechanical life is rated at 10 million operations typical, which for a motor-starting application at 1000 operations per hour (AC-3 maximum) translates to over 10,000 hours of continuous cycling before the contactor wears out mechanically. The arcing time sits between 10 and 15 ms, and the total opening time at AC is 10 to 25 ms — fast enough to clear faults in coordination with upstream motor circuit protectors. Maximum operating frequency varies by duty: 900 cycles/hour in AC-1 resistive loads, 1000 cycles/hour in AC-3 motor starting, and 300 cycles/hour in AC-4 plugging or inching duty. If your application involves frequent reversing or jogging, the AC-4 limit is the one that governs contactor life. The auxiliary contact block (integrated or add-on) carries 10 A at 24 V, 6 A at 230 V, and 3 A at 400 V. These ratings are for the control circuit — feeding the contactor coil, PLC inputs, or status lamps. At 220 V the rating drops to 0.3 A, so if you are switching a 220 V control transformer, verify the inrush does not exceed that figure.","metaTitle":"Siemens SIRIUS 3RT1045-1AG20 Power Contactor, S3 Frame, 45 k","metaDescription":"Siemens SIRIUS 3RT1045-1AG20 power contactor, S3 frame size, rated 45 kW at 500 V AC-3, 21.1 kW at 690 V. Screw terminals, IP20 front. Current production. Sourced to order against","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Contactors"],"specifications":{"Depth":"139 mm","Solid":"2x (0.5 ... 1.5 mm²), 2x (0.75 ... 2.5 mm²), max. 2x (0.75 ... 4 mm²)","Width":"70 mm","at AC":"10 ... 25 ms","Height":"146 mm","Stranded":"2x (10 ... 50 mm²)","at 50 Hz":"0.8 ... 1.1","at 60 Hz":"0.85 ... 1.1","Arcing Time":"10 ... 15 ms","On The Front":"IP20; IP20 on the front with cover / box terminal","1 Rated Value":"50 Hz","2 Rated Value":"60 Hz","During Storage":"-55 ... +80 °C","Of The Terminal":"IP00","at AC-1 maximum":"900 1/h","at AC-2 maximum":"400 1/h","at AC-3 maximum":"1 000 1/h","at AC-4 maximum":"300 1/h","lifecycle_stage":"current","During Operation":"-25 ... +60 °C","Fastening Method":"screw and snap-on mounting onto 35 mm and 75 mm standard mounting rail","Size Of Contactor":"S3","Solid Or Stranded":"2x (2.5 ... 16 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 50 Hz rated value":"110 V","at 500 V rated value":"45 kW","at 60 Hz rated value":"110 V","at 690 V rated value":"21.1 kW","Side-By-Side Mounting":"Yes","at 1000 V rated value":"37 W","For Main Current Circuit":"screw-type terminals","at AC-2 at 400 V rated value":"37 kW","at AC-4 at 400 V rated value":"66 A","Substance Prohibitance (Date)":"05/01/2012","at 40 °C minimum permissible":"50 mm²","at 60 °C minimum permissible":"35 mm²","Insulation Voltage Rated Value":"1 000 V","at 230 V at 60 °C rated value":"38 kW","at 690 V at 60 °C rated value":"114 kW","at 1000 V at 60 °C rated value":"82 W","at AWG cables for main contacts":"2x (10 ... 1/0)","For Auxiliary And Control Circuit":"screw-type terminals","With Type Of Assignment 2 Required":"fuse gL/gG: 160 A","Surge Voltage Resistance Rated Value":"6 kV","With Type Of Coordination 1 Required":"fuse gL/gG: 250 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","reference code according to IEC 81346-2":"Q","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)","Thermal Short-Time Current Limited To 10 S":"760 A","Finely Stranded Without Core End Processing":"2x (10 ... 35 mm²)","apparent holding power of magnet coil at AC":"27 VA","apparent pick-up power of magnet coil at AC":"298 VA","Type Of Voltage Of The Control Supply Voltage":"AC","Required Spacing For Grounded Parts At The Side":"6 mm","contact rating of auxiliary contacts according to UL":"A600 / Q600","Inductive Power Factor With Closing Power Of The Coil":"0.7","Installation Altitude At Height Above Sea Level Maximum":"2 000 m","Inductive Power Factor With The Holding Power Of The Coil":"0.29","Of The Contactor With Added Auxiliary Switch Block Typical":"10 000 000","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","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":null,"sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=406187&mlfb=3RT1045-1AG20","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RT1045-1AG20/alternatives.json"},"ai":{"faq":[{"question":"What are the key power ratings for this contactor?","answer":"In AC-3 motor duty, it is rated at 45 kW at 500 V and 21.1 kW at 690 V. The AC-1 resistive rating is not directly stated, but the operating frequency for AC-1 is 900 cycles/hour. These are the figures to use when sizing for a three-phase induction motor."},{"question":"What is the physical size and mounting arrangement?","answer":"The S3 frame measures 146 mm high, 70 mm wide, and 139 mm deep. It mounts via screw or snap-on onto 35 mm or 75 mm DIN rail, and side-by-side mounting is permitted without derating."},{"question":"What terminal types and conductor sizes does it accept?","answer":"The main circuit uses screw-type terminals. Solid conductors: 2x 0.5 to 1.5 mm², 2x 0.75 to 2.5 mm², max 2x 0.75 to 4 mm². Stranded conductors: 2x 10 to 50 mm². These cover control wiring through to motor feeder cables for a 45 kW load."},{"question":"What protection rating does the contactor have?","answer":"IP20 on the front with the cover or box terminal fitted. The terminal area itself is IP00, so the contactor must be installed inside an enclosure that provides the overall panel ingress rating."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RT1045-1AG20","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/3RT1045-1AG20 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}}