{"schemaVersion":1,"slug":"50r-calculated-residual-instantaneous-overcurrent","name":"Calculated residual instantaneous overcurrent","kind":"function","abbreviation":"50R","aliases":["calculated ground IOC","calculated neutral IOC","ANSI 50R","IEEE 50R"],"category":"measurement-protection","drawingTypes":["SLD","Schematic"],"referenceFamilies":["IEEE / ANSI","Manufacturer"],"summary":"Supervises an instantaneous residual-current element calculated from phase-current measurements in the cited Eaton family.","description":["Supervises an instantaneous residual-current element calculated from phase-current measurements in the cited Eaton family.","The drafting record should connect this function to the phase CT inputs used to calculate residual current, then trace the calculated residual element and earth-fault trip 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 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 phase CT inputs used to calculate residual current.","Trace the calculated residual element and earth-fault trip output."],"drawingChecklist":["Label the phase CT inputs used to calculate residual current.","Cross-reference the calculated residual element and earth-fault trip output.","Retain the complete suffix, selected device tag and manufacturer manual revision."],"distinction":"Eaton's R mapping means calculated residual current; a separate measured residual input is identified as X in the same family.","facts":[{"label":"Function designation","value":"50R"},{"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/50r-calculated-residual-instantaneous-overcurrent","illustration":{"url":"https://eloragrid.ai/library/illustrations/50r-calculated-residual-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."}]}