{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RK4340-3FR51-1BA0","brand":"Siemens","brandSlug":"siemens","productSlug":"3RK4340-3FR51-1BA0","canonicalUrl":"https://aoctrl.com/siemens/3RK4340-3FR51-1BA0","factsUrl":"https://aoctrl.com/api/mcp/products/3RK4340-3FR51-1BA0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RK4340-3FR51-1BA0, motor starter MCU I/O controlled, reversing starter, 2 A AC-3 at 400 V, Class 10, IP55, 340-440 V operating voltage, 20.4-26.4 V DC control supply.","salesMarkdown":"The Siemens SIRIUS 3RK4340-3FR51-1BA0 is an I/O-controlled reversing motor starter designed for direct-on-line reversing of three-phase motors up to 2 A AC-3 at 400 V. It integrates a contactor, bimetal overload relay (Class 10 trip), and short-circuit protection coordination into a single IP55 enclosure — one part number instead of a panel-built stack. The 340-440 V operating voltage range covers standard 400 V industrial mains; the control supply is 20.4-26.4 V DC, so it needs a 24 V DC power supply, not an AC coil circuit. Rated 2 A in AC-3 duty (motor switching), this starter handles small reversing loads: conveyors, gate drives, small hoists, or any application where forward/reverse is needed. The Class 10 bimetal overload matches standard motor thermal curves for general-purpose induction motors — it will trip before the winding overheats on a sustained overload or phase-loss condition. The 2 A AC-3 at 400 V rating is the motor-switching current, not the resistive (AC-1) rating. For a 400 V three-phase motor, 2 A corresponds roughly to a 1.1 kW output — confirm your motor FLA stays under this figure. The operating voltage range of 340-440 V means it works on 400 V nominal systems with typical tolerance, but not on 480 V or 575 V supplies. This is the standard class for most general-purpose induction motors; if your motor has a high-inertia load requiring a longer start time (Class 20 or 30), this starter is not the right fit. No PROFIBUS DP, no PROFINET, no AS-Interface protocol support. This is an I/O-controlled unit — you wire the forward/reverse/stop commands directly to the control terminals. If your line requires fieldbus control, you need a different variant in the SIRIUS family with a communication module. The IP55 enclosure means this starter is dust-protected and can handle water jets from any direction — suitable for washdown areas, outdoor installations under cover, or dusty industrial environments. It is not submersible (IP67 would be needed for that). This helps fitting into tight cabinets or angled machine frames. Dimensions are 145 mm deep, 182 mm wide, 220 mm high — account for cable entry clearance on the bottom and side. Short-circuit protection is designed for circuit-breakers (not fuses). The starter includes short-circuit protection coordination, so you can size the upstream breaker per the manufacturer's tables without adding a separate motor protection breaker.","metaTitle":"Siemens 3RK4340-3FR51-1BA0 SIRIUS Reversing Starter","metaDescription":"Siemens SIRIUS 3RK4340-3FR51-1BA0 reversing motor starter, 2 A AC-3 at 400 V, Class 10 bimetal protection, IP55 enclosure. Current lifecycle.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Motor Starters"],"specifications":{"Depth":"145 mm","Width":"182 mm","Height":"220 mm","Trip Class":"CLASS 10","Type Of Voltage":"DC","lifecycle_stage":"current","Bus Communication":"No","Mounting Position":"+/-180° rotation possible on vertical mounting surface; can be tilted forward and backward by +/- 22.5° on vertical mounting surface","PROFINET protocol":"No","Product Brand Name":"SIRIUS","Type Of Assignment":"1","Product Designation":"motor starter MCU, I/O controlled","protection class IP":"IP55","PROFIBUS DP protocol":"No","Design Of The Product":"reversing starter","Number Of Digital Inputs":"0","Short Circuit Protection":"Yes","at AC at 400 V rated value":"2 A","brake control with 24 V DC":"No","Operating Frequency Minimum":"80 1/h","brake control with 180 V DC":"No","brake control with 400 V AC":"No","brake control with 500 V DC":"No","Type Of The Motor Protection":"bimetal","at AC-3 at 400 V rated value":"2 A","Operating Voltage Rated Value":"340 ... 440 V","Substance Prohibitance (Date)":"05/01/2012","Design Of The Switching Contact":"electromechanical","Operating Frequency 1 Rated Value":"50 Hz","Operating Frequency 2 Rated Value":"60 Hz","Design Of Short-Circuit Protection":"circuit-breakers","Ambient Temperature During Operation":"-25 ... +35 °C","Product Component Motor Brake Output":"No","Type Of Voltage Of The Supply Voltage":"DC","reference code according to IEC 81346-2":"Q","Number Of Poles For Main Current Circuit":"3","control supply voltage at DC rated value":"20.4 ... 26.4 V","with low demand rate according to SN 31920":"50 %","protocol is supported AS-Interface protocol":"No","with high demand rate according to SN 31920":"75 %","operating power at AC-3 at 400 V rated value":"0.8 kW","Product Extension Braking Module For Brake Control":"No","Relative Negative Tolerance Of The Operating Frequency":"-10 %","Relative Positive Tolerance Of The Operating Frequency":"10 %","Type Of Electrical Connection For Main Current Circuit":"screw-type terminals","breaking capacity maximum short-circuit current (Icu) at 400 V rated value":"50 000 A","Adjustable Current Response Value Current Of The Current-Dependent Overload Release":"1.4 ... 2 A"}},"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=404499&mlfb=3RK4340-3FR51-1BA0","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RK4340-3FR51-1BA0/alternatives.json"},"ai":{"faq":[{"question":"Does the Siemens 3RK4340-3FR51-1BA0 support PROFIBUS or PROFINET?","answer":"No. This unit has no PROFIBUS DP, no PROFINET, and no AS-Interface protocol support. It is an I/O-controlled reversing starter — forward, reverse, and stop are wired directly to the control terminals."},{"question":"What is the trip class of 3RK4340-3FR51-1BA0?","answer":"Trip Class 10. The bimetal overload relay will trip within 10 seconds at 600% of the set current, matching standard general-purpose induction motor thermal curves."},{"question":"Where can I buy 3RK4340-3FR51-1BA0?","answer":"Submit an RFQ for current pricing and availability — confirmed at quote time."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RK4340-3FR51-1BA0","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/3RK4340-3FR51-1BA0 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}}