{"schemaVersion":1,"slug":"50g-instantaneous-ground-overcurrent","name":"Instantaneous ground overcurrent","kind":"function","abbreviation":"50G","aliases":["earth IOC","ground instantaneous overcurrent","ANSI 50G","IEEE 50G"],"category":"measurement-protection","drawingTypes":["SLD","Schematic"],"referenceFamilies":["IEEE / ANSI","Manufacturer"],"summary":"Supervises the ground-current input or ground-fault quantity identified by the selected relay.","description":["Supervises the ground-current input or ground-fault quantity identified by the selected relay.","The drafting record should connect this function to the ground CT input, earthing connection and sensor polarity, then trace the ground overcurrent trip and circuit earthing reference. 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 (SEL generator protection feature table). Suffixes are not universal equivalences across products, and this reference supplies neither a protection setting nor certification of the selected scheme."],"readingNotes":["Identify the ground CT input, earthing connection and sensor polarity.","Trace the ground overcurrent trip and circuit earthing reference."],"drawingChecklist":["Label the ground CT input, earthing connection and sensor polarity.","Cross-reference the ground overcurrent trip and circuit earthing reference.","Retain the complete suffix, selected device tag and manufacturer manual revision."],"distinction":"G is application-dependent: in 50G it denotes ground current, while 87G commonly denotes generator differential.","facts":[{"label":"Function designation","value":"50G"},{"label":"Base function","value":"50 — Instantaneous overcurrent"},{"label":"Published mapping","value":"SEL generator protection feature table"},{"label":"Suffix scope","value":"Application or manufacturer specific; check the complete drawing legend and selected device manual."}],"references":[{"sourceId":"pub-function-sel-generator","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/50g-instantaneous-ground-overcurrent","illustration":{"url":"https://eloragrid.ai/library/illustrations/50g-instantaneous-ground-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-sel-generator","title":"Generator protection feature and function comparison","publisher":"Schweitzer Engineering Laboratories","url":"https://selinc.com/products/comparisons/generator-protection/","type":"manufacturer","scope":"Public mappings for generator functions, including phase distance, field/stator ground, thermal RTD, sequence-current and vector-shift applications. Product availability depends on model/options; no settings are provided here.","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."}]}