{"schemaVersion":1,"slug":"59a-auxiliary-input-overvoltage","name":"Auxiliary-input overvoltage","kind":"function","abbreviation":"59A","aliases":["auxiliary overvoltage","auxiliary input OV","ANSI 59A","IEEE 59A"],"category":"measurement-protection","drawingTypes":["SLD","Schematic"],"referenceFamilies":["IEEE / ANSI","Manufacturer"],"summary":"Supervises high voltage on the auxiliary measurement input in the cited Eaton family.","description":["Supervises high voltage on the auxiliary measurement input in the cited Eaton family.","The drafting record should connect this function to the auxiliary voltage input and the electrical node it measures, then trace the auxiliary overvoltage trip or control output. Keep the complete designation and equipment tag together so that the SLD, relay logic and terminal schedule describe the same implementation.","The cited mapping is a public manufacturer example (Eaton ETR family). Suffixes are not universal equivalences across products, and this reference supplies neither a protection setting nor certification of the selected scheme."],"readingNotes":["Identify the auxiliary voltage input and the electrical node it measures.","Trace the auxiliary overvoltage trip or control output."],"drawingChecklist":["Label the auxiliary voltage input and the electrical node it measures.","Cross-reference the auxiliary overvoltage trip or control output.","Retain the complete suffix, selected device tag and manufacturer manual revision."],"distinction":"Auxiliary-input A distinguishes the input circuit here; it does not universally indicate an alarm-only function.","facts":[{"label":"Function designation","value":"59A"},{"label":"Base function","value":"59 — Overvoltage"},{"label":"Published mapping","value":"Eaton ETR family"},{"label":"Suffix scope","value":"Application or manufacturer specific; check the complete drawing legend and selected device manual."}],"references":[{"sourceId":"pub-function-eaton-transformer","relevance":"Public primary-source function or application mapping used to identify this designation; wording and drafting notes are original."},{"sourceId":"ieee-functions","relevance":"Device-number and suffix convention. This page is not a reproduction of the full licensed standard."}],"related":["59-overvoltage","voltage-transformer"],"artwork":"pub-function-box","publishedOn":"2026-10-13","updatedOn":"2026-10-13","provenance":"independent-public-research","url":"https://eloragrid.ai/protection-functions/59a-auxiliary-input-overvoltage","illustration":{"url":"https://eloragrid.ai/library/illustrations/59a-auxiliary-input-overvoltage.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-eaton-transformer","title":"ETR-4000 and ETR-5000 transformer protection function tables","publisher":"Eaton","url":"https://www.eaton.com/us/en-us/catalog/electrical-circuit-protection/transformer-relays.html","type":"manufacturer","scope":"Public transformer-relay mappings including restrained/unrestrained differential, restricted ground differential, main and auxiliary voltage inputs, and measured/calculated earth-current inputs.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"Public primary-source function or application mapping used to identify this designation; wording and drafting notes are original."},{"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":"Device-number and suffix convention. This page is not a reproduction of the full licensed standard."}]}