{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RK4320-3BQ51-1BA2","brand":"Siemens","brandSlug":"siemens","productSlug":"3RK4320-3BQ51-1BA2","canonicalUrl":"https://aoctrl.com/siemens/3RK4320-3BQ51-1BA2","factsUrl":"https://aoctrl.com/api/mcp/products/3RK4320-3BQ51-1BA2","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RK4320-3BQ51-1BA2 reversing motor starter, 0.8 A at 400 V AC-3, AS-Interface bus communication, IP54, Class 10 trip, 205 mm depth, 245 mm width, 215 mm height.","salesMarkdown":"## What this SIRIUS reversing starter is The 3RK4320-3BQ51-1BA2 is a Siemens SIRIUS motor starter MCU designed as a reversing starter for AS-Interface networks. It integrates electromechanical switching contacts, bimetal motor protection (Class 10 trip), and bus communication into one unit — no separate contactor-plus-overload assembly needed. The operating voltage range is 340–440 V, 50/60 Hz. Control supply is 20.4–26.4 V DC, and the unit communicates via the AS-Interface protocol (supported natively, no PROFIBUS or PROFINET onboard). Two digital inputs are available for local control signals. ## Ratings that matter for fit The 0.8 A AC-3 rating at 400 V defines the maximum motor current this starter can switch under full-load starting conditions. Ambient temperature range of -25 to +50 °C covers most indoor panel environments; the IP54 enclosure rating means it's dust-protected and splash-resistant, suitable for installation in cabinets on the plant floor without additional sealing. Mounting flexibility is generous: ±180° rotation possible on a vertical mounting surface, and the unit can be tilted forward/backward by ±22.5° on that same surface — useful when panel layout forces an angled orientation. Dimensions are 205 mm deep, 245 mm wide, 215 mm tall — confirm the DIN rail or backplate footprint before panel cut-out. The reversing starter design means it occupies more space than a non-reversing unit.","metaTitle":"Siemens 3RK4320-3BQ51-1BA2 SIRIUS Reversing Starter, 0.8 A","metaDescription":"Siemens 3RK4320-3BQ51-1BA2 SIRIUS reversing motor starter, 0.8 A at 400 V AC-3, AS-Interface bus, IP54. Active production, sourced 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","Height":"215 mm","Trip Class":"CLASS 10","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":"0.8 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":"0.8 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":"0.2 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":"0.55 ... 0.8 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/f4d6015b4aa97a2a1f8ec69a1aac28da.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=413823&mlfb=3RK4320-3BQ51-1BA2","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RK4320-3BQ51-1BA2/alternatives.json"},"ai":{"faq":[{"question":"What is the rated current of 3RK4320-3BQ51-1BA2 at 400 V?","answer":"0.8 A in both AC-3 (motor starting) and AC general use at 400 V. This is the maximum continuous motor current the starter can handle under full-load conditions."},{"question":"Does 3RK4320-3BQ51-1BA2 support PROFIBUS or PROFINET?","answer":"No. The only bus protocol supported is AS-Interface. PROFIBUS DP and PROFINET are both listed as 'No' in the specifications. For those networks, a different SIRIUS variant with an appropriate communication module would be needed."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RK4320-3BQ51-1BA2","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/3RK4320-3BQ51-1BA2 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}}