{"schemaVersion":1,"slug":"differential-current-measuring-relay","name":"Differential-current measuring relay","kind":"symbol","abbreviation":"I DIFF","aliases":["HCR1F29","VCR1F29"],"category":"measurement-protection","drawingTypes":["SLD","Schematic"],"referenceFamilies":["Manufacturer"],"summary":"A differential-current relay responds to the relationship between specified current inputs.","description":["A differential-current relay responds to the relationship between specified current inputs. The schematic must identify input directions, ratio matching and the protected or monitored zone."],"readingNotes":["Follow polarity and reference directions on all compared current circuits.","The preview is an original explanation of this function. Match the actual drawing convention to its legend and the selected equipment documentation."],"drawingChecklist":["Identify compared inputs","Show polarity references","Link setting and zone documentation"],"distinction":"Differential measurement is not simply a single high-current threshold.","facts":[{"label":"Drawing role","value":"Monitoring element"},{"label":"Representation scope","value":"Functional concept; not an official standard graphic or a product footprint"},{"label":"Public vendor block reference","value":"HCR1F29, VCR1F29 (Autodesk identifiers; not IEC symbol numbers)"},{"label":"Identifier status","value":"The short label is a functional lookup label, not an assigned IEC or IEEE symbol number. Any separately listed Autodesk code is a verified vendor block name."}],"references":[{"sourceId":"pub-symbol-current-relays","relevance":"Public documentation of this equipment function or named vendor variant; the illustration is independently authored and is not the source graphic."}],"related":["current-transformer","relay-coil"],"artwork":"edu-differential-current-measuring-relay","publishedOn":"2026-10-13","updatedOn":"2026-10-13","provenance":"independent-public-research","url":"https://eloragrid.ai/symbols/differential-current-measuring-relay","illustration":{"url":"https://eloragrid.ai/library/illustrations/differential-current-measuring-relay.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"pub-symbol-current-relays","title":"AutoCAD Electrical: Current monitoring relays","publisher":"Autodesk","url":"https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-E0DDA638-4664-4F1E-B191-29A4C40C4A0A.htm","type":"cad-reference","scope":"Public vendor catalogue naming and functional variants. Vendor block names are not IEC identifiers. Linked for reference; no graphics or CAD files are redistributed.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"Public documentation of this equipment function or named vendor variant; the illustration is independently authored and is not the source graphic."}]}