G 3PH PM
Permanent-magnet synchronous generator
A permanent-magnet synchronous generator provides an AC source using a permanent magnetic excitation system.
SLD / Schematic
Symbols · WTG T4
Full-converter wind turbine generator (Type 4)
A wind turbine whose entire generator output passes through a full-rated back-to-back converter before reaching the network.
In plain English
What does Full-converter wind turbine generator (Type 4) mean?
In a Type 4 turbine the generator, commonly a permanent-magnet or wound-field synchronous machine and sometimes an induction machine, is fully decoupled from the network by a back-to-back converter rated for the whole turbine output. The machine-side converter rectifies variable-frequency generator output to a DC link and the grid-side converter produces network-frequency AC.
A simple example
Single-line drawings show the generator circle, a machine-side converter block, a DC link with chopper or brake resistor, a grid-side converter block and the line filter before the step-up transformer. Some drawings collapse this to a generator and a single converter symbol labelled with the conversion direction.
What the drawings help you do
The network sees a converter, not a rotating machine, so fault current is limited to the converter capability and reactive output is a control function. The symbol does not tell you whether the converter is grid-following or grid-forming, which must be checked in the plant control description.
This particular reference
A wind turbine whose entire generator output passes through a full-rated back-to-back converter before reaching the network. A Type 4 turbine routes all power through the converter; a DFIG routes only rotor slip power through it.
- DC
- Direct current: electricity flowing in one direction.
- AC
- Alternating current: electricity whose direction changes periodically.
- Winding
- A coil of conductor inside an electrical machine or transformer.
Read the source: Generator symbol variants · AutoCAD Electrical: Power station and substation concepts
SLD · WTG T4
What it represents
In a Type 4 turbine the generator, commonly a permanent-magnet or wound-field synchronous machine and sometimes an induction machine, is fully decoupled from the network by a back-to-back converter rated for the whole turbine output. The machine-side converter rectifies variable-frequency generator output to a DC link and the grid-side converter produces network-frequency AC.
Single-line drawings show the generator circle, a machine-side converter block, a DC link with chopper or brake resistor, a grid-side converter block and the line filter before the step-up transformer. Some drawings collapse this to a generator and a single converter symbol labelled with the conversion direction.
The network sees a converter, not a rotating machine, so fault current is limited to the converter capability and reactive output is a control function. The symbol does not tell you whether the converter is grid-following or grid-forming, which must be checked in the plant control description.
How to read it
- Treat the turbine short-circuit contribution as converter-limited.
- A DC chopper resistor in the link absorbs energy during network faults; it is not a load.
Information to show or reference
- State generator type and full converter rating.
- Show DC link chopper and line filter.
- Reference converter control mode and ride-through data.
A distinction that matters
A Type 4 turbine routes all power through the converter; a DFIG routes only rotor slip power through it.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Generator symbol variants
Public permanent-magnet synchronous generator symbol context.
AutoCAD Electrical: Power station and substation concepts
Wind station representation used as site-level 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.
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