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Home / Technical Articles / What are the consequences of high harmonic distortion levels?

The plant engineer’s worst fear…

Just as high blood pressure can create stress and serious problems in the human body, high levels of harmonic distortion can create stress and resultant problems for the utility’s distribution system and the plant’s distribution system, as well as all of the equipment that is serviced by that distribution system.

What are the consequences of high harmonic distortion levels?
What are the consequences of high harmonic distortion levels? (on photo: Shuvajit Bala ABB UniGear – 12kV AIS; credit: Muhammad Qadeer via Linkedin)

The result may be the plant engineer’s worst fear – the shutting down of important plant equipment ranging from a single machine to an entire line or process.

Equipment shutdown can be caused by a number of events. As an example, the higher voltage peaks that are created by harmonic distortion put extra stress on motor and wire insulation, which ultimately can result in insulation breakdown and failure.

In addition, harmonics increase rms current, resulting in increased operating temperatures for many pieces of equipment, greatly reducing equipment life.

Table below summarizes some of the negative consequences that harmonics can have on typical equipment found in the plant environment.

Negative Consequences of Harmonics on Plant Equipment

Current Harmonic Distortion Problems 
 Capacitors Blown fuses, reduced capacitor life
 Motors Reduced motor life, inability to fully load motor
 Fuses/breakers False/spurious operation, damaged components
 Transformers Increased copper losses, reduced capacity
Voltage Harmonic Distortion Problems
 Transformers Increased noise, possible insulation failure
 Motors Mechanical fatigue
 Electronic loads Misoperation

While these effects are categorized by problems created by current and voltage harmonics, current and voltage harmonic distortion usually exist together (current harmonic distortion causes voltage harmonic distortion) .

Harmonic distortion disrupts plants. Of greatest importance is the loss of productivity, throughput, and, possibly, sales.

These occur because of process shutdowns due to the unexpected failure of motors, drives, power supplies, or just the spurious tripping of breakers. Plant engineers realize how costly downtime can be and pride themselves in maintaining low levels of plant downtime. In addition, maintenance and repair budgets can be severely stretched.

For example, every 10°C rise in the operating temperatures of motors or capacitors can cut equipment life by 50%.

Reference: Power factor correction: a guide for the plant engineer – Eaton

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Edvard Csanyi

Electrical engineer, programmer and founder of EEP. Highly specialized for design of LV/MV switchgears and LV high power busbar trunking (<6300A) in power substations, commercial buildings and industry facilities. Professional in AutoCAD programming.


  1. Marlene M Biscaha
    Apr 02, 2023

    My neighbor’s air conditioner has a harmonic hum that hits the wall of my house and is absorbed all over the house. I am stressed out not only by the noise which is also in my pillow but my B12 number has gone down under 4. The doctor has put me on 1000 mgs of B12. This noise is on and off night and day seven days a week for 13 months. What other health issues should I be aware of? She will not fix it.

  2. Bryan Lee
    Mar 07, 2016

    Hi Edvard, thanks for sharing the informative article!

    May we know what’s the impact for High Harmonics on the busbars, their connections and the Switchgears (AIS/GIS) in the longer term? Appreciate your advice.

    Best Regards,
    Bryan Lee-UA

  3. Khan
    Oct 22, 2015

    Can u tell which is the ideal location or part of the circuit or distribution network from where to connect the harmonic analyzer to accurately determine harmonics?? main bus bar coming from generators or distri trafo or lower d/s to LV MCC bus bar for example?

  4. ramasubramanian.s
    Mar 14, 2015

    Please send the Power factor correction details and capacitors details ,Harmonic filter details

  5. rob
    Dec 08, 2014

    More info on larger power generation units in remote areas and hybrid power systems for locations where there are no transformers fuel savings vs Kw generated any new info on saving people money with low voltage DC inverters feeding off panels and battery banks.

    This de-rating of power systems due to heat and humidity synchronising with new purpose designed PLC units.

    This would all be very interesting.

    Thanking you.

  6. Liu Eddie
    Nov 26, 2014

    I am a technical engineer. My friend introduce the EEP apps to me and I’d like to update via it. Thanks.

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