{"schemaVersion":1,"slug":"50x-measured-ground-instantaneous-overcurrent","name":"Measured ground instantaneous overcurrent","kind":"function","abbreviation":"50X","aliases":["measured neutral IOC","measured ground IOC","ANSI 50X","IEEE 50X"],"category":"measurement-protection","drawingTypes":["SLD","Schematic"],"referenceFamilies":["IEEE / ANSI","Manufacturer"],"summary":"Supervises the instantaneous element using a separately measured ground or neutral input in the cited Eaton family.","description":["Supervises the instantaneous element using a separately measured ground or neutral input in the cited Eaton family.","The drafting record should connect this function to the dedicated ground/neutral current input and external CT, then trace the measured-current element and associated trip path. 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 EMR 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 dedicated ground/neutral current input and external CT.","Trace the measured-current element and associated trip path."],"drawingChecklist":["Label the dedicated ground/neutral current input and external CT.","Cross-reference the measured-current element and associated trip path.","Retain the complete suffix, selected device tag and manufacturer manual revision."],"distinction":"In this Eaton mapping X identifies a measured input; it should not be assumed to mean a generic auxiliary relay.","facts":[{"label":"Function designation","value":"50X"},{"label":"Base function","value":"50 — Instantaneous overcurrent"},{"label":"Published mapping","value":"Eaton EMR family"},{"label":"Suffix scope","value":"Application or manufacturer specific; check the complete drawing legend and selected device manual."}],"references":[{"sourceId":"pub-function-eaton-motor","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":["50-instantaneous-overcurrent","current-transformer"],"artwork":"pub-function-box","publishedOn":"2026-10-13","updatedOn":"2026-10-13","provenance":"independent-public-research","url":"https://eloragrid.ai/protection-functions/50x-measured-ground-instantaneous-overcurrent","illustration":{"url":"https://eloragrid.ai/library/illustrations/50x-measured-ground-instantaneous-overcurrent.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-motor","title":"EMR motor protection: public function comparison","publisher":"Eaton","url":"https://www.eaton.com/us/en-us/catalog/electrical-circuit-protection/motor-relays.html","type":"manufacturer","scope":"Public motor-relay application mappings including jam/stall protection, current input variants, breaker failure and motor differential. Suffix interpretation applies to the cited family.","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."}]}