HPF
Damped high-pass harmonic filter
A shunt filter with a resistor across its reactor, giving low impedance over a broad band of higher harmonics.
SLD / Schematic
Symbols · HF
Single-tuned harmonic filter
A shunt series-LC branch tuned near one harmonic order to sink that harmonic current from the network.
In plain English
What does Single-tuned harmonic filter mean?
A single-tuned filter is a capacitor and reactor in series, connected in shunt and tuned to resonate near one harmonic frequency, often slightly below the 5th, 7th or 11th. At that frequency it presents a low impedance and draws harmonic current away from the network, while at fundamental frequency it supplies capacitive reactive power.
A simple example
Drawings show a capacitor and reactor in series on a shunt branch, labelled with the tuned order, and often several such branches for different orders. Unbalance protection for the capacitor bank and a dedicated breaker are normally shown.
What the drawings help you do
A tuned filter creates a parallel resonance with the network at a frequency just below its tuning, which can amplify other harmonics. The symbol does not show the network impedance scan or detuning tolerance, so the harmonic study must accompany it.
This particular reference
A shunt series-LC branch tuned near one harmonic order to sink that harmonic current from the network. A single-tuned filter targets one harmonic order; a damped high-pass filter attenuates a broad band above its corner frequency.
- 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: Capacitor and filter product offerings · AutoCAD Electrical: Reactors and inductors
SLD / Schematic · HF
What it represents
A single-tuned filter is a capacitor and reactor in series, connected in shunt and tuned to resonate near one harmonic frequency, often slightly below the 5th, 7th or 11th. At that frequency it presents a low impedance and draws harmonic current away from the network, while at fundamental frequency it supplies capacitive reactive power.
Drawings show a capacitor and reactor in series on a shunt branch, labelled with the tuned order, and often several such branches for different orders. Unbalance protection for the capacitor bank and a dedicated breaker are normally shown.
A tuned filter creates a parallel resonance with the network at a frequency just below its tuning, which can amplify other harmonics. The symbol does not show the network impedance scan or detuning tolerance, so the harmonic study must accompany it.
How to read it
- Read the harmonic order label on each branch.
- The filter also supplies fundamental reactive power.
Information to show or reference
- State tuned order, Mvar and quality factor.
- Show breaker and unbalance protection.
- Reference harmonic study.
A distinction that matters
A single-tuned filter targets one harmonic order; a damped high-pass filter attenuates a broad band above its corner frequency.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Capacitor and filter product offerings
Public passive and harmonic filter product context.
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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