{"schemaVersion":1,"slug":"synchronous-generator-with-brushless-exciter","name":"Synchronous generator with brushless exciter","kind":"symbol","abbreviation":"G 3~ BX","aliases":["brushless alternator","generator with rotating rectifier","PMG-excited alternator"],"category":"microgrid-systems","drawingTypes":["SLD","Schematic"],"referenceFamilies":["IEC","IEEE / ANSI"],"summary":"A synchronous alternator shown with its exciter machine and rotating rectifier, as used on most generating sets.","description":["Most modern generating sets use a brushless excitation system: a small exciter generator on the same shaft feeds a rotating diode rectifier, which supplies DC to the main field without slip rings. The automatic voltage regulator controls the exciter field, and some sets add a permanent-magnet pilot exciter to power the regulator independently of the output voltage.","Schematics draw the main generator circle, a smaller exciter circle on the same shaft line and a rectifier bridge between them, with the regulator connected to the exciter field. Single-line diagrams often reduce this to the main machine with a note, so the expanded form usually appears on the generator control schematic.","The symbol does not give the regulator type, the excitation support during short circuits, or whether a pilot exciter is fitted. Those determine whether the set can sustain fault current long enough for downstream protection to operate."],"readingNotes":["The rotating rectifier is shown inside the shaft boundary; it is not an external rectifier.","A permanent-magnet pilot exciter indicates excitation support independent of terminal voltage."],"drawingChecklist":["Identify regulator type and sensing connections.","State pilot exciter presence.","Reference fault-current support data."],"distinction":"This form shows the excitation chain explicitly; the plain synchronous generator symbol shows only the main machine.","facts":[{"label":"Excitation path","value":"Exciter, rotating rectifier, main field"},{"label":"Regulator input","value":"Exciter field current"},{"label":"Slip rings","value":"None"},{"label":"Preview","value":"Independent educational illustration; consult the applicable standard and project legend for the exact graphic"}],"references":[{"sourceId":"pub-object-cummins-application","relevance":"Public generator-set application manual describing alternator excitation arrangements."},{"sourceId":"autodesk-generators","relevance":"Public synchronous generator symbol variants."}],"related":["three-phase-synchronous-generator","diesel-generator-set","single-phase-bridge-rectifier","53-exciter-or-dc-generator-relay"],"artwork":"s28-synchronous-generator-with-brushless-exciter","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","plainEnglish":{"title":"What does Synchronous generator with brushless exciter mean?","introduction":"Most modern generating sets use a brushless excitation system: a small exciter generator on the same shaft feeds a rotating diode rectifier, which supplies DC to the main field without slip rings. The automatic voltage regulator controls the exciter field, and some sets add a permanent-magnet pilot exciter to power the regulator independently of the output voltage.","example":"Schematics draw the main generator circle, a smaller exciter circle on the same shaft line and a rectifier bridge between them, with the regulator connected to the exciter field. Single-line diagrams often reduce this to the main machine with a note, so the expanded form usually appears on the generator control schematic.","drawings":"The symbol does not give the regulator type, the excitation support during short circuits, or whether a pilot exciter is fitted. Those determine whether the set can sustain fault current long enough for downstream protection to operate.","terms":[{"name":"DC","meaning":"Direct current: electricity flowing in one direction."},{"name":"Signal","meaning":"Electrical information passed between devices, rather than necessarily the main power supply."},{"name":"Rating","meaning":"A value stating the conditions for which equipment is specified."}],"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":"T-030 liquid-cooled generator set application manual","url":"https://www.cummins.com/sites/default/files/2024-08/t030-Liquid-cooled-gen-set-application-manual.pdf"},{"label":"Generator symbol variants","url":"https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-09BE3BB5-9118-4302-8061-3888692E538F.htm"}],"detail":"A synchronous alternator shown with its exciter machine and rotating rectifier, as used on most generating sets. This form shows the excitation chain explicitly; the plain synchronous generator symbol shows only the main machine.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/synchronous-generator-with-brushless-exciter","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/synchronous-generator-with-brushless-exciter.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"pub-object-cummins-application","title":"T-030 liquid-cooled generator set application manual","publisher":"Cummins","url":"https://www.cummins.com/sites/default/files/2024-08/t030-Liquid-cooled-gen-set-application-manual.pdf","type":"manufacturer","scope":"Public manufacturer application manual, Issue 9, February 2015; context for generator integration. Current selected-generator documentation and applicable regulations control implementation.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"Public generator-set application manual describing alternator excitation arrangements."},{"id":"autodesk-generators","title":"Generator symbol variants","publisher":"Autodesk","url":"https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-Electrical/files/GUID-09BE3BB5-9118-4302-8061-3888692E538F.htm","type":"cad-reference","scope":"DC and three-phase synchronous generator categories.","checkedOn":"2026-10-13","reuse":"link-only","relevance":"Public synchronous generator symbol variants."}]}