{"schemaVersion":1,"slug":"neutral-current-relay","name":"Neutral-current measuring relay","kind":"symbol","abbreviation":"K","aliases":["current in neutral protection","neutral overcurrent relay","HCR1F32"],"category":"measurement-protection","drawingTypes":["Schematic","SLD"],"referenceFamilies":["IEC","Manufacturer"],"summary":"Measuring relay fed from a CT in a neutral conductor or star-point connection, responding to neutral current.","description":["This relay form is used where a CT is installed in a neutral conductor or in the earthing connection of a transformer or generator star point. Current there indicates earth faults or, in four-wire systems, heavy unbalance and triplen harmonic loading, depending on where the CT sits.","The symbol identifies the measured conductor but not the purpose. A neutral CT in the star-point earth lead gives standby earth-fault protection, while one in the four-wire neutral of a feeder sees load unbalance as well, so settings and grading differ greatly."],"readingNotes":["Confirm whether the CT is in the neutral conductor or the earthing lead.","Check grading against downstream earth-fault devices."],"drawingChecklist":["Show neutral CT location","State setting and delay","Reference grading study"],"distinction":"A neutral-current relay measures one neutral path; a residual connection sums the three phase CTs to derive the same quantity.","facts":[{"label":"Measured quantity","value":"Current in a neutral or star-point conductor"},{"label":"Publisher reference token","value":"HCR1F32 (Autodesk identifier; not an IEC database ID)"},{"label":"Preview","value":"Independent educational concept; consult the publisher and applicable standard for the exact graphic"}],"references":[{"sourceId":"pub-symbol-current-relays","relevance":"Public AutoCAD Electrical relay listing that names the In Neutral block; the illustration is independently drawn."},{"sourceId":"iec-diagrams","relevance":"IEC context for graphical symbols used in diagrams; no IEC graphic is reproduced."}],"related":["residual-connection-of-phase-cts","earth-fault-current-relay","51-time-overcurrent"],"artwork":"s28-neutral-current-relay","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","plainEnglish":{"title":"What does Neutral-current measuring relay mean?","introduction":"This relay form is used where a CT is installed in a neutral conductor or in the earthing connection of a transformer or generator star point. Current there indicates earth faults or, in four-wire systems, heavy unbalance and triplen harmonic loading, depending on where the CT sits.","example":"The symbol identifies the measured conductor but not the purpose. A neutral CT in the star-point earth lead gives standby earth-fault protection, while one in the four-wire neutral of a feeder sees load unbalance as well, so settings and grading differ greatly.","drawings":"Confirm whether the CT is in the neutral conductor or the earthing lead. Check grading against downstream earth-fault devices. A neutral-current relay measures one neutral path; a residual connection sums the three phase CTs to derive the same quantity.","terms":[{"name":"Winding","meaning":"A coil of conductor inside an electrical machine or transformer."},{"name":"Coil","meaning":"A wound conductor that can produce a magnetic field when energised."},{"name":"Terminal","meaning":"An identified point where a conductor connects."}],"diagram":"flow","steps":["Identify the device and form","Read the connections and state","Check the equipment reference"],"caption":"A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.","sources":[{"label":"AutoCAD Electrical: Current monitoring relays","url":"https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-E0DDA638-4664-4F1E-B191-29A4C40C4A0A.htm"},{"label":"IEC graphical symbols for diagrams","url":"https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/"}],"detail":"Measuring relay fed from a CT in a neutral conductor or star-point connection, responding to neutral current. A neutral-current relay measures one neutral path; a residual connection sums the three phase CTs to derive the same quantity.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/neutral-current-relay","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/neutral-current-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 AutoCAD Electrical relay listing that names the In Neutral block; the illustration is independently drawn."},{"id":"iec-diagrams","title":"IEC graphical symbols for diagrams","publisher":"IEC","url":"https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/","type":"standard","scope":"IEC 60617 and related symbol-design publications. Full database access requires a subscription.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"IEC context for graphical symbols used in diagrams; no IEC graphic is reproduced."}]}