{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RK4320-3PQ51-1BA3","brand":"Siemens","brandSlug":"siemens","productSlug":"3RK4320-3PQ51-1BA3","canonicalUrl":"https://aoctrl.com/siemens/3RK4320-3PQ51-1BA3","factsUrl":"https://aoctrl.com/api/mcp/products/3RK4320-3PQ51-1BA3","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RK4320-3PQ51-1BA3 reversing motor starter, AS-Interface bus communication, 12 A AC-3 at 400 V, Class 10, IP54, 205 x 245 x 215 mm.","salesMarkdown":"The 3RK4320-3PQ51-1BA3 is a SIRIUS reversing starter — meaning it handles forward/reverse motor direction in a single enclosure, saving panel space over two separate contactors. The 12 A rating at 400 V AC-3 (motor duty) tells you it switches induction motors up to that current under full load, not just resistive loads. The Class 10 trip curve means it disconnects within 10 seconds at 600% overload — right-sized for standard squirrel-cage motors that don't need the longer delay of Class 20. It communicates over AS-Interface (the protocol is supported), with 2 digital inputs onboard for local sensors or pushbuttons. The control supply is 24 V DC (20.4...26.4 V range), so it drops into a standard 24 V control panel without a separate supply module. The enclosure measures 245 mm wide x 215 mm high x 205 mm deep — that's a compact footprint for a reversing starter with integrated brake control. It mounts on a vertical surface with +/-180° rotation possible, and can be tilted forward/backward by +/-22.5° on that surface, giving flexibility in tight cabinets. IP54 protection means it's dust-protected and splash-resistant — suitable for dry indoor industrial environments but not for washdown zones. ## Motor protection and brake control in one unit The motor protection uses a bimetal overload relay — a proven thermal model that tracks motor heating directly. Short-circuit protection is handled by upstream circuit breakers (not fuses), which simplifies coordination and reset. The unit includes a motor brake output for 400 V AC, so it can control a mechanical brake on the motor shaft without an external contactor. Rated for 80 operating cycles per hour minimum — that's one start every 45 seconds, which covers most conveyor and pump cycling. For higher-demand applications, the SN 31920 duty ratings are 50% (low demand rate) and 75% (high demand rate), meaning it's designed for continuous rated current at those duty cycles.","metaTitle":"Siemens 3RK4320-3PQ51-1BA3 SIRIUS Reversing Starter","metaDescription":"Siemens 3RK4320-3PQ51-1BA3 SIRIUS motor starter MCU for AS-Interface. Reversing starter, 12 A at 400 V AC-3, Class 10, IP54. Active production, quoted to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Motor Starters"],"specifications":{"Depth":"205 mm","Width":"245 mm","title":"3RK4320-3PQ51-1BA3","Height":"215 mm","Trip Class":"CLASS 10","description":"SIRIUS MCU motor starter Enclosure degree of protection IP54 metal Communication AS-Interface electromechanically switching Short-circuit protection with circuit breaker Reversing starter Brake 400 V AC (internal) Performance class 12.00 A Motor circuit breaker with bi-metal thermal Rotary operating mechanism gray/black Connection power M screw connection Standard product","Type Of Voltage":"DC","lifecycle_stage":"current","Bus Communication":"Yes","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 for AS-Interface","protection class IP":"IP54","PROFIBUS DP protocol":"No","Design Of The Product":"reversing starter","Number Of Digital Inputs":"2","Short Circuit Protection":"Yes","at AC at 400 V rated value":"12 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":"Yes","brake control with 500 V DC":"No","Type Of The Motor Protection":"bimetal","at AC-3 at 400 V rated value":"12 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 ... +50 °C","Product Component Motor Brake Output":"Yes","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":"Yes","with high demand rate according to SN 31920":"75 %","operating power at AC-3 at 400 V rated value":"5.5 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","maximum short-circuit current breaking capacity (Icu) at 400 V rated value":"50 000 A","Adjustable Current Response Value Current Of The Current-Dependent Overload Release":"9 ... 12.5 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/31999ef2a4a5afa7590016b0e99d25f2.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=279239&mlfb=3RK4320-3PQ51-1BA3"},"ai":{"faq":[{"question":"What is the AC-3 motor rating for this reversing starter?","answer":"The same 12 A applies at 400 V AC for general use. This is the rating that governs motor sizing — not the resistive load rating."},{"question":"Does the 3RK4320-3PQ51-1BA3 include motor brake control?","answer":"Yes, it has a motor brake output for 400 V AC, integrated into the starter. No external brake contactor is needed for AC brake coils."},{"question":"What compliance documentation is available for this part?","answer":"The unit is designed to IEC 60947 standards as part of the SIRIUS family."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RK4320-3PQ51-1BA3","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/3RK4320-3PQ51-1BA3 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-07-22T19:47:38.189Z","lastPublished":"2026-07-22T19:47:38.189Z","indexable":true}}