{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RT1044-3BM40","brand":"Siemens","brandSlug":"siemens","productSlug":"3RT1044-3BM40","canonicalUrl":"https://aoctrl.com/siemens/3RT1044-3BM40","factsUrl":"https://aoctrl.com/api/mcp/products/3RT1044-3BM40","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RT1044-3BM40 power contactor, Size S3, screw-type terminals, 37 kW at 500 V AC-3, 55 A at 400 V AC-4, screw and snap-on mounting.","salesMarkdown":"The 3RT1044-3BM40: The AC-3 rating of 37 kW at 500 V is the headline motor-switching capacity — it tells you the contactor can handle a 3-phase induction motor of that power under normal starting conditions (6–8x inrush, switching off at rated current). The AC-4 rating of 55 A at 400 V is the more demanding duty class: it applies when the contactor makes and breaks stalled-rotor current, so if your application involves frequent reversing or inching, this 55 A figure is the one to size against, not the AC-3 kW number. The AC-1 maximum operating frequency of 1 000 switching cycles per hour and AC-4 maximum of 300 cycles per hour set the thermal limits for repetitive operation — useful for high-cycle conveyor or press applications. The auxiliary contact ratings span from 10 A at 24 V up to 6 A at 230 V and 3 A at 400 V, covering a range of PLC and relay interface voltages. ## Environmental and Installation Conditions The enclosure protection is IP20 on the front with the cover or box terminal fitted; the terminal itself is IP00, meaning the wiring compartment requires the panel's own IP rating. Wire sizes: solid conductors accept 2x (0.25... 2.5 mm²) for control wiring, while the main power terminals accept stranded 2x (10... 50 mm²) or solid/stranded 2x (2.5... 16 mm²).","metaTitle":"Siemens 3RT1044-3BM40 SIRIUS Power Contactor, Size S3, 37 kW","metaDescription":"Siemens 3RT1044-3BM40 SIRIUS power contactor, Size S3, screw terminals, 37 kW at 500 V AC-3, 55 A at 400 V AC-4. Current production. DIN rail mount. RoHS compliant.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Contactors"],"specifications":{"Depth":"152 mm","Solid":"2x (0.25 ... 2.5 mm²)","Width":"70 mm","at DC":"14 ... 20 ms","Height":"146 mm","Stranded":"2x (10 ... 50 mm²)","Arcing Time":"10 ... 15 ms","Rated Value":"220 V","On The Front":"IP20; IP20 on the front with cover / box terminal","Initial Value":"0.8","During Storage":"-55 ... +80 °C","Of The Terminal":"IP00","at AC-1 maximum":"1 000 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","Full-Scale Value":"1.1","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 500 V rated value":"37 kW","at 690 V rated value":"18.6 kW","Side-By-Side Mounting":"Yes","at 1000 V rated value":"30 W","For Main Current Circuit":"screw-type terminals","at AC-2 at 400 V rated value":"30 kW","at AC-4 at 400 V rated value":"55 A","Substance Prohibitance (Date)":"05/01/2012","at 40 °C minimum permissible":"35 mm²","at 60 °C minimum permissible":"35 mm²","Insulation Voltage Rated Value":"1 000 V","at 230 V at 60 °C rated value":"34 kW","at 690 V at 60 °C rated value":"102 kW","at 1000 V at 60 °C rated value":"66 W","at AWG cables for main contacts":"2x (10 ... 1/0)","For Auxiliary And Control Circuit":"spring-loaded terminals","With Type Of Assignment 2 Required":"fuse gL/gG: 125 A","closing power of magnet coil at DC":"15 W","holding power of magnet coil at DC":"15 W","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 (24 ... 14)","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 (0.25 ... 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)","Thermal Short-Time Current Limited To 10 S":"600 A","Finely Stranded Without Core End Processing":"2x (0.25 ... 2.5 mm²)","Type Of Voltage Of The Control Supply Voltage":"DC","Required Spacing For Grounded Parts At The Side":"6 mm","contact rating of auxiliary contacts according to UL":"A600 / Q600","Installation Altitude At Height Above Sea Level Maximum":"2 000 m","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=289476&mlfb=3RT1044-3BM40","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RT1044-3BM40/alternatives.json"},"ai":{"faq":[{"question":"What are the key motor ratings for this contactor?","answer":"The AC-3 rating is 37 kW at 500 V for standard squirrel-cage motor starting. The AC-4 rating is 55 A at 400 V for heavy-duty jogging or inching applications. It also carries an AC-2 rating of 30 kW at 400 V for slip-ring motors."},{"question":"What wire sizes does the 3RT1044-3BM40 accept?","answer":"The main power terminals accept stranded conductors of 2x (10... 50 mm²) or solid/stranded of 2x (2.5... 16 mm²). The control terminals accept solid conductors of 2x (0.25... 2.5 mm²)."},{"question":"What is the mounting method for this contactor?","answer":"It uses screw and snap-on mounting onto 35 mm and 75 mm standard mounting rails, which is the standard DIN-rail format for panel integration."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RT1044-3BM40","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/3RT1044-3BM40 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}}