G 3PH SYNC
Three-phase synchronous generator
A three-phase synchronous generator supplies a documented AC source associated with its mechanical prime mover and excitation system.
SLD / Schematic
Symbols · G 3~ BX
Synchronous generator with brushless exciter
A synchronous alternator shown with its exciter machine and rotating rectifier, as used on most generating sets.
In plain English
What does Synchronous generator with brushless exciter mean?
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.
A simple 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.
What the drawings help you do
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.
This particular reference
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.
- DC
- Direct current: electricity flowing in one direction.
- Signal
- Electrical information passed between devices, rather than necessarily the main power supply.
- Rating
- A value stating the conditions for which equipment is specified.
Read the source: T-030 liquid-cooled generator set application manual · Generator symbol variants
SLD / Schematic · G 3~ BX
What it represents
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.
How to read it
- 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.
Information to show or reference
- Identify regulator type and sensing connections.
- State pilot exciter presence.
- Reference fault-current support data.
A distinction that matters
This form shows the excitation chain explicitly; the plain synchronous generator symbol shows only the main machine.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
T-030 liquid-cooled generator set application manual
Public generator-set application manual describing alternator excitation arrangements.
Generator symbol variants
Public synchronous generator symbol variants.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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