{"schemaVersion":1,"slug":"14-underspeed-device","name":"Underspeed device","kind":"function","abbreviation":"14","aliases":["underspeed relay","low speed protection","ANSI 14","IEEE device 14"],"category":"measurement-protection","drawingTypes":["SLD","Schematic"],"referenceFamilies":["IEEE / ANSI"],"summary":"Responds to machine speed below the required operating level.","description":["Responds to machine speed below the required operating level.","In a drafting package, connect this reference to the speed input and start-up supervision logic. The associated drawing should trace the underspeed alarm or stopping circuit; the number identifies the role and does not specify the terminal arrangement, ratings or operating settings."],"readingNotes":["Identify the speed input and start-up supervision logic.","Trace the underspeed alarm or stopping circuit."],"drawingChecklist":["Label the speed input and start-up supervision logic.","Cross-reference the underspeed alarm or stopping circuit.","Identify the device tag, manual revision and logic drawing that define this implementation."],"distinction":"An underspeed element measures rotation; low electrical frequency is a different measured quantity.","facts":[{"label":"ANSI / IEEE function number","value":"14"},{"label":"Drawing context","value":"The speed input and start-up supervision logic"},{"label":"Application scope","value":"Protection or apparatus-control role; exact implementation is defined by the equipment documentation."}],"references":[{"sourceId":"pub-function-sel-numbers","relevance":"Public manufacturer number/name association. Drafting explanations are independently written."},{"sourceId":"ieee-functions","relevance":"Normative device-number publication; exact edition wording and compliance require the licensed standard."}],"related":["motor","52-ac-circuit-breaker"],"artwork":"pub-function-box","publishedOn":"2026-10-13","updatedOn":"2026-10-13","provenance":"independent-public-research","url":"https://eloragrid.ai/protection-functions/14-underspeed-device","illustration":{"url":"https://eloragrid.ai/library/illustrations/14-underspeed-device.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"pub-function-sel-numbers","title":"ANSI device-number and suffix reference table","publisher":"Schweitzer Engineering Laboratories","url":"https://selinc.com/pt/products/tables/ansi/","type":"manufacturer","scope":"Public Portuguese-language base-number and application-suffix table. Used to cross-check public number associations. Application-specific and historical labels need the selected drawing legend; this table is not a substitute for the licensed IEEE standard.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"Public manufacturer number/name association. Drafting explanations are independently written."},{"id":"ieee-functions","title":"IEEE C37.2-2022: power-system device function numbers","publisher":"IEEE","url":"https://ieeexplore.ieee.org/document/9984140","type":"standard","scope":"Device function numbers, acronyms and contact designations. The full publication may require access through IEEE.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"Normative device-number publication; exact edition wording and compliance require the licensed standard."}]}