{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RK4320-3BR51-1BA0","brand":"Siemens","brandSlug":"siemens","productSlug":"3RK4320-3BR51-1BA0","canonicalUrl":"https://aoctrl.com/siemens/3RK4320-3BR51-1BA0","factsUrl":"https://aoctrl.com/api/mcp/products/3RK4320-3BR51-1BA0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RK4320-3BR51-1BA0 reversing motor starter, 0.8 A at 400 V AC-3, IP55, AS-Interface bus communication, Trip Class 10, 3-pole, 145 x 182 x 220 mm.","salesMarkdown":"## SIRIUS reversing starter with AS-Interface bus The Siemens SIRIUS 3RK4320-3BR51-1BA0 is a reversing motor starter designed for motor control applications requiring forward/reverse operation. It integrates the contactor, overload relay, and reversing interlock into a single compact unit, communicating over AS-Interface for direct integration with higher-level control systems. The Trip Class 10 bimetal overload protection ensures the motor is disconnected before winding damage occurs during a stalled-rotor condition. ## IP55 enclosure and mounting flexibility The enclosure is not submersible but handles splashing and condensation without internal damage. Dimensions of 145 mm depth, 182 mm width, and 220 mm height fit standard enclosure layouts with room for adjacent devices. The control supply accepts 20.4 to 26.4 V DC, matching standard 24 V DC industrial power supplies. ## Active production and sourcing posture The unit supports AS-Interface protocol (AS-i) for communication, reducing point-to-point wiring compared to conventional parallel-wired starters. It does not support PROFIBUS DP or PROFINET, so network integration requires an AS-i gateway if the control system uses those fieldbuses. Ambient temperature range of -25 to +35 °C limits installation to climate-controlled or moderate environments; derating may apply above 35 °C. The bimetal overload is non-adjustable for trip class, so coordination with upstream short-circuit protection (circuit-breakers) must follow the manufacturer's selectivity tables.","metaTitle":"Siemens 3RK4320-3BR51-1BA0 SIRIUS Reversing Starter, 0.8 A","metaDescription":"Siemens SIRIUS 3RK4320-3BR51-1BA0 reversing motor starter, 0.8 A at 400 V AC-3, IP55, AS-Interface bus communication, Trip Class 10.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Motor Starters"],"specifications":{"Depth":"145 mm","Width":"182 mm","title":"3RK4320-3BR51-1BA0","Height":"220 mm","Trip Class":"CLASS 10","description":"SIRIUS MCU motor starter Enclosure degree of protection IP55 plastic Communication AS-Interface electromechanically switching Short-circuit protection with circuit breaker Reversing starter Brake without Performance class 0.80 A Motor circuit breaker with bi-metal thermal Manual operation without 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":"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":"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 ... +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":"Yes","with high demand rate according to SN 31920":"75 %","operating power at AC-3 at 400 V rated value":"0.18 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,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/1a0fbfa83007964494aecf46559f8c21.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=369734&mlfb=3RK4320-3BR51-1BA0"},"ai":{"faq":[{"question":"What is the closest alternative to 3RK4320-3BR51-1BA0 in the SIRIUS family?","answer":"No official pin-compatible successor or cross-reference is listed for this specific reversing starter variant. The SIRIUS 3RK4 series includes other current ratings and communication options, but a direct drop-in replacement without re-engineering the panel wiring or AS-Interface configuration is not confirmed. Verify the BOM position and network protocol before substituting."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RK4320-3BR51-1BA0","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/3RK4320-3BR51-1BA0 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-08-11T15:51:03.652Z","lastPublished":"2026-08-11T15:51:03.652Z","indexable":true}}