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  • Writer's pictureCy Cates

Harmonic Distortion: Which mitigation method do you choose?

Harmonic Mitigation

Harmonic Distortion: 3 Types of Current Correction

or Voltage Correction - Which type do you choose?

From Applied Energy’s Critical Power Presentation June 12th, 2017

Common Solutions

For over 35 years, current correction has been the approach for reducing harmonic noise (or distortion) in Industrial facilities. Years ago, harmonic distortion and voltage imbalance were of a lesser concern.

Why is harmonic distortion and voltage imbalance more important now than before?

  • Electronics becoming smaller and more sensitive.

  • The wide spread use of Variable Speed Drives

  • The wide spread use of voltage sensitive LED light bulbs & other sensitive electronics.

  • Heavy Concentration of Electronic Loads

Because current correction is commonly thought to be the only option for improving power quality, many organizations are unaware of the numerous pitfalls of this approach. Below are some examples of current correction your facility may be employing:

  1. Current Correction: Passive Harmonic Filter

  2. Shunts harmonics to ground, only filtering specific harmonics (typically 5th and 7th)

  3. Must be applied individually to devices, to protect the system from the device and to isolate the device from the system.

  4. Minimal noise filtering, no voltage correction, no correction of phase angles.

  5. Uses excessive amount of energy to do its job. Most efficient at the highest load.

  6. Current Correction: Active Harmonic Filter

  7. Senses harmonics, injects current to cancel out harmonics. In a noisy system, it can malfunction and cause problems.

  8. Each filter can be applied to one or several devices, but not all. Inter-harmonic noise can cause problems and malfunction.

  9. Can cause higher order harmonics which distort the voltage waveform.

  10. Consumes a large amount of energy.

  11. ​Current Correction: Current Smoothing Reactor (or Line Reactor)

  12. Application is on a per-device basis, typically added before a drive to limit the current to the drive.

  13. Installation is cumbersome, requiring the reactor to be wired to the drive in series.

  14. Limits voltage to the drive, resulting in additional acceleration time and reduced torque, and may malfunction.

  15. Minimal noise filtering, no voltage protection, and no correction of phase angle.

  16. Consumes a large amount of energy.

  17. Voltage Correction: Phaseback VSGR

The Future-Proof Solution

  • ​Because voltage correction targets the source of power quality issues, the voltage waveform, the result is that nearly all power quality issues are addressed automatically, economically, at the speed of current flow.

  • Voltage correction offers innumerable benefits.

In 2002, there became a new method of protecting the quality of power in Industrial facilities, when Phaseback VSGR with voltage correction was introduced.

Compare Current Correction solutions to the table below.

With Phaseback VSGR, get these benefits:

1. Arc Flash/Arc Fault Protection: Automatically prevent 85% of events 2. Eliminate Voltage Spikes and single phase Voltage Sags 3. Correct Phase Voltage / Ground Imbalance 4. Correct Phase Loss from High Impedance Grounds 5. Maintain Phase Angle Differential 120° 6. Correct Phase Voltage Instability 7. Eliminate Voltage Harmonic Noise on Ungrounded Systems.

See Note 13 below.

8. Correct Voltage Waveform Distortion

9. Correct Noisy Ground Reference & Frequency

10. Prevent Arcing Ground Faults and Alarm

11. Increases Operational Efficiency- Reduce kW and Ground Current

12. AFPT = REMOVE Current & Voltage Harmonics plus the other 11 items above. Note 12.



12. AFPT (Arc Flash Preventing Transformer) provides the perfect Electrical System for today’s loads, with Phaseback VSGR, will save more energy & eliminate the need for other Harmonic mitigating devices that use energy. Also, SPDs, HRG, & snuffers are not needed. 13. For Grounded WYE systems, Phaseback VSGR will provide all but 7 in the above table. Applied Energy also offers The Silencer for Grounded WYE systems to eliminate Harmonics.


Current correction is an inadequate solution, as it is a symptomatic approach to the problems of today. It is inefficient, offers few benefits, and is not an acceptable solution for the present industrial landscape. Its limitations are likely to become more obvious in the future.

There is only one device that provides effective Voltage Correction, Harmonic Mitigation, and all of needed benefits. Applied Energy LLC's patented (2002) Phaseback VSGR, is all that is needed to resolve most, if not all Power Quality issues on the electrical system!

Voltage Stabilizing Ground Reference (VSGR)

Grounding choices IEEE142

For more information, visit us at, and take a look at our Critical Power Presentation, where these topics, and many others, are described in detail. Applied Energy Critical Power Presentation (YouTube): 1. 06:51min - Voltage Distortion: Without and With Correction, 2. 21:04min - Voltage Waveform Correction: The Root Cause Solution, 3. 22:30min - Correcting the Voltage Waveform: A Cause Solution, 4. 30:19min- Phase Voltage Imbalances 832 647 4606 cell

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