{"schemaVersion":1,"slug":"arc-suppression-coil","name":"Arc suppression coil","kind":"symbol","abbreviation":"ASC","aliases":["Petersen coil","earth-fault neutraliser","resonant earthing coil"],"category":"microgrid-systems","drawingTypes":["SLD"],"referenceFamilies":["IEC","IEEE / ANSI"],"summary":"An adjustable reactor between neutral and earth tuned to cancel the network capacitive earth-fault current.","description":["An arc suppression coil is a reactor connected between the system neutral and earth, tuned so that its inductive current balances the capacitive current that flows during a single phase-to-earth fault. The residual fault current becomes very small, so transient arcing faults often self-extinguish and the network can keep running with a sustained earth fault.","Drawings show an inductor with an adjustment arrow between a transformer or earthing transformer neutral and earth, often with a parallel resistor switched in briefly to help fault location. Automatic tuning controllers and neutral voltage measurement are drawn alongside.","Resonant earthing needs dedicated earth-fault detection, such as transient or admittance-based protection, because fault current is too small for simple overcurrent relays. The symbol does not show the tuning range or the detection method."],"readingNotes":["An adjustment arrow on the reactor shows tuning capability.","Look for a parallel resistor used for fault location."],"drawingChecklist":["State tuning range in amperes.","Show earthing transformer and resistor.","Reference earth-fault detection method."],"distinction":"An arc suppression coil cancels capacitive fault current; a neutral earthing resistor limits fault current but does not cancel it.","facts":[{"label":"Element","value":"Adjustable reactor"},{"label":"Connection","value":"Neutral to earth"},{"label":"Detection required","value":"Sensitive or transient earth-fault protection"},{"label":"Preview","value":"Independent educational illustration; consult the applicable standard and project legend for the exact graphic"}],"references":[{"sourceId":"pub-symbol-earth-fault","relevance":"Public earth-fault and neutral earthing protection context."},{"sourceId":"pub-symbol-reactors","relevance":"Public reactor symbol family context."}],"related":["neutral-earthing-resistor","adjustable-core-inductor","67nief-transient-or-intermittent-earth-fault-protection","zigzag-winding-connection"],"artwork":"s28-arc-suppression-coil","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","plainEnglish":{"title":"What does Arc suppression coil mean?","introduction":"An arc suppression coil is a reactor connected between the system neutral and earth, tuned so that its inductive current balances the capacitive current that flows during a single phase-to-earth fault. The residual fault current becomes very small, so transient arcing faults often self-extinguish and the network can keep running with a sustained earth fault.","example":"Drawings show an inductor with an adjustment arrow between a transformer or earthing transformer neutral and earth, often with a parallel resistor switched in briefly to help fault location. Automatic tuning controllers and neutral voltage measurement are drawn alongside.","drawings":"Resonant earthing needs dedicated earth-fault detection, such as transient or admittance-based protection, because fault current is too small for simple overcurrent relays. The symbol does not show the tuning range or the detection method.","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":"Phase","meaning":"One of the related AC waveforms in a power system."}],"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":"Residual current and neutral-earthing protection context","url":"https://new.abb.com/medium-voltage/digital-substations/campaigns/earth-fault-protection-portfolio/earth-fault-offering"},{"label":"AutoCAD Electrical: Reactors and inductors","url":"https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-BAD50DBF-0951-44A0-BB4C-A57B4A4ED895.htm"}],"detail":"An adjustable reactor between neutral and earth tuned to cancel the network capacitive earth-fault current. An arc suppression coil cancels capacitive fault current; a neutral earthing resistor limits fault current but does not cancel it.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/arc-suppression-coil","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/arc-suppression-coil.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-earth-fault","title":"Residual current and neutral-earthing protection context","publisher":"ABB","url":"https://new.abb.com/medium-voltage/digital-substations/campaigns/earth-fault-protection-portfolio/earth-fault-offering","type":"manufacturer","scope":"Public manufacturer explanation of the equipment function and selection context.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"Public earth-fault and neutral earthing protection context."},{"id":"pub-symbol-reactors","title":"AutoCAD Electrical: Reactors and inductors","publisher":"Autodesk","url":"https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-BAD50DBF-0951-44A0-BB4C-A57B4A4ED895.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 reactor symbol family context."}]}