SVC
Static var compensator
A shunt reactive power compensator built from thyristor-controlled reactors, thyristor-switched capacitors and filters.
SLD
Symbols · TCR
Thyristor-controlled reactor
A shunt reactor in series with anti-parallel thyristors whose firing angle sets the reactive power absorbed.
In plain English
What does Thyristor-controlled reactor mean?
A thyristor-controlled reactor is an air-core reactor in series with a pair of anti-parallel thyristor valves. Delaying the firing angle reduces the current conduction period, so the reactor absorbs a continuously adjustable amount of reactive power from zero to its full rating.
A simple example
Drawings show the reactor symbol with the thyristor pair below it, usually in a delta connection with the reactor split into two halves on either side of the valve. It is the inductive branch of a static var compensator and also appears in some arc furnace compensation schemes.
What the drawings help you do
Partial conduction generates harmonic currents, mainly odd orders, so the TCR is almost always accompanied by filters. The symbol does not show the filter arrangement or the valve cooling, which is a significant part of the installation.
This particular reference
A shunt reactor in series with anti-parallel thyristors whose firing angle sets the reactive power absorbed. A TCR varies its absorption continuously; a thyristor-switched reactor is only fully on or fully off.
- Terminal
- An identified point where a conductor connects.
- Rating
- A value stating the conditions for which equipment is specified.
- Schematic
- A drawing showing function and connections rather than physical appearance.
Read the source: Static Var Compensators (SVC) · AutoCAD Electrical: Reactors and inductors
SLD / Schematic · TCR
What it represents
A thyristor-controlled reactor is an air-core reactor in series with a pair of anti-parallel thyristor valves. Delaying the firing angle reduces the current conduction period, so the reactor absorbs a continuously adjustable amount of reactive power from zero to its full rating.
Drawings show the reactor symbol with the thyristor pair below it, usually in a delta connection with the reactor split into two halves on either side of the valve. It is the inductive branch of a static var compensator and also appears in some arc furnace compensation schemes.
Partial conduction generates harmonic currents, mainly odd orders, so the TCR is almost always accompanied by filters. The symbol does not show the filter arrangement or the valve cooling, which is a significant part of the installation.
How to read it
- The reactor is often drawn in two halves with the valve between them.
- Delta connection cancels triplen harmonics under balanced conditions.
Information to show or reference
- State reactor rating and firing range.
- Show valve and connection.
- Reference associated filters.
A distinction that matters
A TCR varies its absorption continuously; a thyristor-switched reactor is only fully on or fully off.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Static Var Compensators (SVC)
Public SVC page naming the thyristor-controlled reactor branch.
AutoCAD Electrical: Reactors and inductors
Public reactor symbol family 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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