# Dynamic voltage restorer

Canonical URL: https://eloragrid.ai/symbols/dynamic-voltage-restorer
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: DVR
Drawing use: SLD
Reference families: IEC, IEEE / ANSI

A series converter that injects a corrective voltage through a transformer to ride a sensitive load through voltage sags.

## In plain English

### What does Dynamic voltage restorer mean?

A dynamic voltage restorer is connected in series between the supply and a sensitive load through an injection transformer. When the supply voltage sags, a converter fed from a DC store or from the supply itself injects the missing voltage so the load sees an almost constant voltage, typically for sags lasting up to a few seconds.

### A simple example

Single-line diagrams show an injection transformer with its primary in series with the feeder, its secondary connected to a converter, and a DC capacitor or storage element. A bypass switch around the injection transformer allows the device to be taken out of service.

### What the drawings help you do

A DVR corrects sags but does not supply the load during a full outage, unlike a UPS. The symbol does not show the maximum sag depth or duration it can correct, which depends on the stored energy and converter rating.

### This particular reference

A series converter that injects a corrective voltage through a transformer to ride a sensitive load through voltage sags. A DVR injects series voltage for sags; a STATCOM injects shunt current to support bus voltage.

### Terms

- DC: Direct current: electricity flowing in one direction.
- Winding: A coil of conductor inside an electrical machine or transformer.
- Rating: A value stating the conditions for which equipment is specified.

Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference
A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.

- [IEC graphical symbols for diagrams](https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/)
- [Bidirectional three-/single-phase AC/DC PFC and inverter application note](https://www.infineon.com/assets/row/public/documents/24/42/infineon-ac-dc-pfc-11-kw-high-efficiency-high-density-bidirectional-three-single-phase-inverter-applicationnotes-en.pdf)


## What it represents

A dynamic voltage restorer is connected in series between the supply and a sensitive load through an injection transformer. When the supply voltage sags, a converter fed from a DC store or from the supply itself injects the missing voltage so the load sees an almost constant voltage, typically for sags lasting up to a few seconds.
Single-line diagrams show an injection transformer with its primary in series with the feeder, its secondary connected to a converter, and a DC capacitor or storage element. A bypass switch around the injection transformer allows the device to be taken out of service.
A DVR corrects sags but does not supply the load during a full outage, unlike a UPS. The symbol does not show the maximum sag depth or duration it can correct, which depends on the stored energy and converter rating.

## How to read it

- The series transformer, not a shunt connection, identifies a DVR.
- Check the bypass arrangement for maintenance.

## Information to show or reference

- State load rating, sag depth and duration corrected.
- Show injection transformer and bypass.
- Reference energy store.

## Important distinction

A DVR injects series voltage for sags; a STATCOM injects shunt current to support bus voltage.

## Facts

- Connection: Series, through injection transformer
- Corrects: Voltage sags and swells
- Outage support: None
- Preview: Independent educational illustration; consult the applicable standard and project legend for the exact graphic

## Public references

- [IEC graphical symbols for diagrams](https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/) — IEC. IEC graphical symbol context for transformers and converters.
- [Bidirectional three-/single-phase AC/DC PFC and inverter application note](https://www.infineon.com/assets/row/public/documents/24/42/infineon-ac-dc-pfc-11-kw-high-efficiency-high-density-bidirectional-three-single-phase-inverter-applicationnotes-en.pdf) — Infineon Technologies. Public converter stage context.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.