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 · GTG
Gas turbine generator
A combustion gas turbine coupled to a synchronous generator, often through a gearbox, shown as a generating unit.
In plain English
What does Gas turbine generator mean?
A gas turbine generator uses a continuous-combustion turbine to drive a synchronous generator, often through a reduction gearbox for smaller industrial machines. Units range from microturbines of tens of kilowatts with high-speed alternators and inverters, up to large industrial turbines feeding a medium-voltage bus.
A simple example
The drawing usually shows a turbine glyph, a trapezoid widening in the direction of flow, joined by a shaft line to the generator circle. A generator step-up transformer, generator breaker and neutral earthing equipment follow on the single-line diagram.
What the drawings help you do
Microturbines with high-speed alternators produce high-frequency output that must pass through a rectifier and inverter, so check whether a converter sits between the machine and the bus. The symbol does not state fuel, start method or ambient derating.
This particular reference
A combustion gas turbine coupled to a synchronous generator, often through a gearbox, shown as a generating unit. A gas turbine is a continuous-combustion rotating prime mover; a gas engine is reciprocating.
- Winding
- A coil of conductor inside an electrical machine or transformer.
- 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: IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams · AutoCAD Electrical: Power station and substation concepts
SLD · GTG
What it represents
A gas turbine generator uses a continuous-combustion turbine to drive a synchronous generator, often through a reduction gearbox for smaller industrial machines. Units range from microturbines of tens of kilowatts with high-speed alternators and inverters, up to large industrial turbines feeding a medium-voltage bus.
The drawing usually shows a turbine glyph, a trapezoid widening in the direction of flow, joined by a shaft line to the generator circle. A generator step-up transformer, generator breaker and neutral earthing equipment follow on the single-line diagram.
Microturbines with high-speed alternators produce high-frequency output that must pass through a rectifier and inverter, so check whether a converter sits between the machine and the bus. The symbol does not state fuel, start method or ambient derating.
How to read it
- A trapezoid on the shaft line indicates the turbine; a gearbox may be drawn as a small box between turbine and generator.
- Look for a converter stage on microturbine packages.
Information to show or reference
- State ISO rating and site derating.
- Show gearbox, generator breaker and earthing.
- Reference start system and black-start capability.
A distinction that matters
A gas turbine is a continuous-combustion rotating prime mover; a gas engine is reciprocating.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
IEEE/ANSI 315-1975: graphic symbols for electrical and electronics diagrams
Graphic-symbol standards context for machines and prime movers.
AutoCAD Electrical: Power station and substation concepts
Public power station representation context.
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.
Explore related references
GG
Gas engine generator set
A spark-ignited reciprocating engine on natural gas, biogas or LPG driving an alternator, shown as a generating source.
SLD
GEN
Generator
An electrical generating source represented in a power-system drawing.
SLD / Schematic
87G
Generator differential protection
Compares current measurements bounding the selected generator differential zone.
Protection functions
Put the reference into a drawing workflow.
Elora Grid helps electrical teams work with drawings, specifications and equipment information. Explore the drafting workflow or join the early-access waitlist.