{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"3RU5166-5FB1","brand":"Siemens","brandSlug":"siemens","productSlug":"3RU5166-5FB1","canonicalUrl":"https://aoctrl.com/siemens/3RU5166-5FB1","factsUrl":"https://aoctrl.com/api/mcp/products/3RU5166-5FB1","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIRIUS 3RU5166-5FB1 thermal overload relay, 3-pole, adjustable current range 1.8-2.5 A, Class 10, screw terminals, for motor protection.","salesMarkdown":"## Motor protection relay for the SIRIUS line The 3RU5166-5FB1: It mounts directly under a contactor or as a standalone unit, with screw terminals on both the main and auxiliary circuits. The adjustable current response range is 1.8 to 2.5 A, with a rated operational current of 2.5 A, making it suitable for smaller motor loads that need Class 10 trip protection against sustained overcurrent. It operates on 50 to 60 Hz supply and withstands surge voltages up to 8 kV, giving it solid noise immunity in industrial environments with switching transients. ## Class 10 trip curve and what it means for your motor The 3-pole design covers all three phases, and the adjustable dial lets you fine-tune the trip point to match the motor nameplate FLA. Set it at the motor's full-load amps, not the relay's maximum rating. Ambient compensation is built into the SIRIUS 3RU5 series, so the trip characteristic stays consistent whether the panel runs at 25 °C or 55 °C — no manual derating needed for normal enclosure temperatures. The 3RU5166-5FB1 is stocked in the independent distribution channel and can be quoted to order against your BOM quantity. RoHS compliance is covered by the substance prohibitance date of 09/03/2013, meaning the relay meets the EU RoHS directive for materials restriction.","metaTitle":"Siemens 3RU5166-5FB1 SIRIUS Thermal Overload Relay","metaDescription":"Siemens 3RU5166-5FB1 SIRIUS thermal overload relay, adjustable 1.8-2.5 A, Class 10, 3-pole. Active production. Sourced to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Overload Relays"],"specifications":{"Per Pole":"0 W","lifecycle_stage":"current","During Transport":"-55 ... +80 °C","Product Brand Name":"SIRIUS","Product Designation":"Thermal overload relay","Substance Prohibitance (Date)":"09/03/2013","Operating Frequency Rated Value":"50 ... 60 Hz","Operational Current Rated Value":"2.5 A","Relative Humidity During Operation":"0 ... 100 %","Surge Voltage Resistance Rated Value":"8 kV","Number Of Poles For Main Current Circuit":"3","Adjustable Current Response Value Current Of The Current-Dependent Overload Release":"1.8 ... 2.5 A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/9cf7036b6d5b2d93e60bb29de3d89b18.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=621471&mlfb=3RU5166-5FB1","alternativesUrl":"https://aoctrl.com/api/mcp/products/3RU5166-5FB1/alternatives.json"},"ai":{"faq":[{"question":"How can I get pricing and availability for 3RU5166-5FB1?","answer":"Submit a request with your target quantity, and current pricing and lead time will be confirmed at quote time."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/3RU5166-5FB1","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/3RU5166-5FB1 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}}