Learn more about our services

What are Harmonics?

When we think of ac voltages and currents, we normally visualise perfect sine waves with a frequency of 50 Hz. Unfortunately, given the rapid increase in IT and process control equipment, this is now rarely the case.

Harmonics are frequencies that are superimposed upon the fundamental 50 Hz signal that are an integer multiple of 50 Hz; i.e. the 3rd harmonic is 150 Hz, the 5thharmonic is 250 Hz and so on.

These harmonics are not just a mathematical representation of a distorted waveform, they are real, and their effects are predictable and measurable.

Two men in high vis shake hands under an energy tower.

Why do we need to know this?

Neglecting to address substantial levels of voltage and current harmonic distortion can lead to various problems on site. Such oversight can lead to diminished performance, overheating of assets, and the potential failure of components or systems. An issue of specific concern involves certain types of harmonics known as “triplens” - namely the 3rd, 5th, 9th, and 15th harmonics.

These triplens can lead to an accumulation of neutral currents, and in extreme cases, the neutral conductor may end up carrying more current than the line conductor. This poses a significant risk in 4-wire systems, which typically are equipped with only 3-pole protective devices.

Beyond the immediate safety risks, unchecked harmonics also contribute to inefficiency and wastage. Addressing these harmonic distortions is crucial for enhancing operational efficiency and is a key step towards achieving Net Zero goals.

How do we measure Harmonics?

Harmonic Analysis is the procedure of measuring and studying the characteristics of an electrical power system to identify, predict and mitigate issues associated with high levels of harmonics.

It involves installing high-speed specialist power analysers, for a minimum of a week and a maximum sample interval of 10 minutes, to monitor the load and collect vital information on the day-to-day running of an industrial or commercial building.

In addition to harmonic analysis, the advanced analysis equipment we employ also records other important power quality indicators.

Fluke 125

The Fluke 125B ScopeMeter is a rugged and compact tool for industrial troubleshooting, integrating an oscilloscope, multimeter, and recorder. It's designed to provide detailed diagnostics on equipment, identifying signal anomalies and assessing electrical signal quality. With features like Connect-and-View™ triggering, it simplifies waveform analysis. Data can be easily downloaded for further analysis, and its long battery life ensures on-the-go usability in harsh environments.

Fluke 451-II

The Fluke 434-II Energy Analyser and 435-II Power Quality and Energy Analyser are tools designed to minimize downtime, troubleshoot power quality issues, and assess energy wastage costs. They provide comprehensive measurements and data output optimized for quick problem-solving. With simultaneous parameter measurements and various data display formats, they enable easy analysis and decision-making for maintenance tasks. Detailed event data facilitates rapid problem correlation within your facility.

How do we treat Harmonics?

In order to ensure the highest power quality for your building or facility, it is necessary to treat harmonics.
Harmonic treatment can be performed by two methods: filtering or cancellation.


Harmonic filters (passive/active) are typically deployed at asset level. A harmonic filter consists of a capacitor bank and an induction coil.
The filter is designed or tuned to the predetermined non-linear load and to filter a predetermined harmonic frequency range. Usually this frequency range only accounts for one harmonic frequency.  

This application is mostly used when specified for a UPS or variable frequency drive motor in a manufacturing plant.


Harmonic cancellation is typically deployed for full site harmonic treatment and usually is sited as close as possible to the main incomer.

Harmonic cancellation is performed with harmonic cancelling transformers also known as phase-shifting transformers. A harmonic cancelling transformer is a relatively new power quality product for mitigating harmonic problems in electrical distribution systems. This type of transformer has patented built-in electromagnetics technology designed to remove high neutral current and the most harmful harmonics from the 3rd through 21st.

The technique used in these transformers is called “low zero phase sequencing and phase shifting”. These transformers can be used to treat existing harmonics in buildings or facilities. This same application can be designed into new construction to prevent future harmonics problems.

The impact of untreated Harmonics

Neutral Wire Overload

Large load currents in the neutral wires of a 3 phase system - this can result in a potential fire hazard.

Transformer Overheating

Overheating of standard electrical supply transformers which shortens the life of a transformer and will eventually destroy it. When a transformer fails, the cost of lost productivity during the emergency repair far exceeds the replacement cost of the transformer itself.

High Voltage Distortion

High voltage distortion refers to irregularities or fluctuations in voltage levels beyond standard parameters. This phenomenon can lead to various issues such as equipment malfunction, increased energy consumption, and potential damage to electrical components.

High Current Distortion and Excessive Current Draw on Circuits

High current distortion involves irregular or excessive fluctuations in electrical current flowing through circuits. This can result in overloading circuits, overheating components, and posing safety hazards.

High Neutral-to-ground Voltage Often Greater than 2 volts

High neutral-to-ground voltage, exceeding 2 volts, poses a potential safety risk in electrical systems. This condition may indicate grounding issues or faults, which can lead to equipment damage or electrical shocks.

High Voltage and Current Distortions

High voltage and current distortions refer to irregularities or fluctuations in both voltage and current levels beyond standard parameters. These distortions can lead to various issues such as equipment malfunction, increased energy consumption, and potential damage to electrical components.

Poor Performing Power Factor Correction Equipment

Poor performing power factor correction equipment results in inefficient power usage and increased energy costs. It fails to adequately optimise power factor, leading to wasted energy and potential penalties from utility companies.

Resonance That Produces Over-current Surges

Resonance causing over-current surges occurs when the natural frequencies of an electrical system coincide with external or internal frequencies, leading to amplified currents. These surges can damage equipment, disrupt operations, and pose safety risks

False Tripping of Circuit Breakers

False tripping of circuit breakers occurs when circuit breakers trip unnecessarily due to issues such as overload, short circuits, or faulty equipment. This can disrupt operations, cause downtime, and lead to unnecessary maintenance.

Our Procedure

At Direct Energy Solutions, we ensure that all client facilities undergoing our services are subjected to our comprehensive 3-point Harmonics Check System (3HCS).

Green tick

Detection and Analysis

The first step would typically involve identifying the presence and levels of harmonic distortions in an electrical system. This could include measuring and analysing the voltage and current waveforms for deviations from the desired sinusoidal shape, particularly looking for the presence of triplens or other harmonic orders.

Green tick

Assessment of Impact

The second point might assess the impact of these distortions on the electrical system. This could involve evaluating the effects on equipment performance, energy efficiency, and the risk of overheating or failure of components, as well as the potential for circuit breaker malfunction.

Green tick

Recommendation and Implementation of Solutions

The final stage would likely involve proposing and implementing solutions to mitigate or eliminate the identified harmonic issues. This could include installing harmonic filters, making adjustments to the electrical network, or recommending changes in equipment or operational practices to minimise harmonic generation.

Leave your details and let our experts do the hard work.

Check - Elements Webflow Library - BRIX Templates

Thank you

Thanks for reaching out. We will get back to you soon.
Oops! Something went wrong while submitting the form.
By clicking “Accept All Cookies”, you agree to the storing of cookies on your device to enhance site navigation, analyze site usage, and assist in our marketing efforts. View our Privacy Policy for more information.