{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RK4320-3HQ51-0BA3","brand":"Siemens","brandSlug":"siemens","productSlug":"3RK4320-3HQ51-0BA3","canonicalUrl":"https://aoctrl.com/siemens/3RK4320-3HQ51-0BA3","factsUrl":"https://aoctrl.com/api/mcp/products/3RK4320-3HQ51-0BA3","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS motor starter MCU for AS-Interface, 3RK4320-3HQ51-0BA3, direct starter, 3.2 A AC-3 at 400 V, CLASS 10, IP54, 205 x 245 x 215 mm.","salesMarkdown":"## What is the 3RK4320-3HQ51-0BA3? It's a direct starter with electromechanical switching contacts, rated for 3.2 A at AC-3 duty on a 400 V supply, and provides motor protection via a bimetal trip element set to CLASS 10. The unit operates on a DC control supply voltage of 20.4 to 26.4 V and draws its main power from a 340 to 440 V AC line at 50 or 60 Hz. The CLASS 10 trip class ensures the bimetal overload relay disconnects the motor within 10 seconds under locked-rotor conditions, protecting windings from thermal damage during a stall. This is the spec that governs real-world motor protection, not the higher AC-1 resistive rating. ## Where is it used? This motor starter mounts on a vertical surface with +/-180° rotation possible, and can be tilted forward and backward by +/-22.5°. The IP54 ingress protection means it's sealed against dust ingress and splashing water — suitable for installation in control cabinets on factory floors where occasional washdown or airborne particulates are present. With 2 digital inputs and bus communication via AS-Interface, it integrates into a distributed I/O architecture. The 205 mm depth, 245 mm width, and 215 mm height dimensions dictate the enclosure cutout and clearance for cable glands.","metaTitle":"Siemens 3RK4320-3HQ51-0BA3 SIRIUS MCU, AS-Interface","metaDescription":"Siemens SIRIUS 3RK4320-3HQ51-0BA3 motor starter MCU for AS-Interface. 3.2 A AC-3 at 400 V, CLASS 10, IP54. Sourced to order against RFQ.","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":"direct starter","Number Of Digital Inputs":"2","Short Circuit Protection":"Yes","at AC at 400 V rated value":"3.2 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":"Yes","brake control with 500 V DC":"No","Type Of The Motor Protection":"bimetal","at AC-3 at 400 V rated value":"3.2 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 ... +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":"1.1 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":"2.2 ... 3.2 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=324795&mlfb=3RK4320-3HQ51-0BA3","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RK4320-3HQ51-0BA3/alternatives.json"},"ai":{"faq":[{"question":"Where can I buy 3RK4320-3HQ51-0BA3?","answer":"The Siemens 3RK4320-3HQ51-0BA3 is sourced to order against an RFQ through independent industrial distribution. Submit a request for quote to confirm current availability and pricing at the time of your order."},{"question":"Is 3RK4320-3HQ51-0BA3 compatible with AS-Interface?","answer":"Yes, the 3RK4320-3HQ51-0BA3 supports the AS-Interface protocol for bus communication. It does not support PROFIBUS DP or PROFINET protocols."},{"question":"What is the trip class of 3RK4320-3HQ51-0BA3?","answer":"The motor protection is rated CLASS 10, meaning the bimetal overload relay trips within 10 seconds under locked-rotor conditions at the set current."},{"question":"What are the alternatives to 3RK4320-3HQ51-0BA3?","answer":"The closest functional second-source within the SIRIUS family is the 3RT1044-1FB46 contactor-based starter, but it lacks the integrated AS-Interface bus communication and motor brake output of this MCU. For a direct AS-Interface MCU replacement, the 3RK4320-3HQ51-0BA3 is the specific order code."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RK4320-3HQ51-0BA3","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/3RK4320-3HQ51-0BA3 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}}