A good power quality equates to high-end productivity, low rate of equipment failure, and minimal damage costs. Hence, this is the rationale why you need to have a responsible energy consumption and conscious electrical usage into your homes.

At a domestic level, you won’t be adversely affected by power quality problems as your devices require a lower power voltage. However, J. Stones (2003) reveals that power quality can pose humongous complications on big industrial and commercial companies. In his book entitled Electrical Engineer’s Reference Book, Stones identifies the attributed weakness of power quality on different industrial processes. Industries will suffer in the long run when the issue of power quality is not addressed at the possible opportune.

If this happens to your business, or even in your production company, the worst-case scenario results in inflicting grave loss of your profit and could lead to much-expanded complications, such as death to a human life.

To avoid any potential threat caused by power quality, you need to understand nine of the most common power quality problems and the tips on maintaining a good power quality.

What is Power Quality?

Since the discovery of electricity and the rise of electrical inventions, the electrical energy serves as the beating heart of the engineering and commerce industry, medical science, research, and development. Behind your technological upbringing is the role of a power quality.

Power quality explains the difference between the expected and actual performance of an electrical power with an electrical device. It is the backbone of every resolution to the arising problems related to electricity. In other words, power quality provides a harmonic content indication to an alternating current power system.

How do you measure power quality?

Power quality monitoring programs assess and evaluate the wide quality performance of your power devices. Today, many industrial and commercial end-users have experienced power disturbances on their device usage. As such, electrical problems boil down to the data performance of power quality, explaining the causation of existing electrical issues.

Circuit Specialists suggest two simple ways to determine power quality in their system: first, is to use a harmonic analyzer, and second, is to use oscilloscopes.

Harmonic Analyzers

Harmonic meters or harmonic analyzers are simple measuring instruments used to record and ascertain harmonic distortion data, where it displays a waveform screen meter, current probes, and voltage probes.

Harmonics is one of the recurring electronic problems, affecting electrical voltages and current. As such, high harmonic voltage causes failure in machinery and equipment.


An oscilloscope or scope measures repetitive high-frequency waveforms or waveforms that contain high-frequency noise on power and control circuits. It displays voltage signals as waveforms – a visual representation of the variation of voltage over time.

Note that a digital storage scope can capture and store waveform data, where more than one electrical parameter may be viewed and stored.

What are the 9 Common Power Quality Problems?

#1 Voltage Sags (Dips)

Voltage sags, or better known as voltage dips, reduce 10% of the normal voltage or recommended usage, such as an abrupt dropping of 120-voltage to 90 volts. It commonly occurs when high-current loads are switched on that can potentially produce a ripple effect across devices.

Usually, voltage sags take place for a single cycle or a second.  The common causes of voltage sags are irregular increase of loads, such as motors starting and short circuits, causing a loose connection and abrupt increase in source impedance.

Voltage sags can damage your IT equipment like microprocessor-based control systems, and can lose the efficiency of electric rotating machines.

#2 Short-duration Interruptions

A short-duration interruption explains why there is a decrease in the voltage supply level to less than 10% of nominal up to one-minute duration. The common causes of short duration-interruptions are the reclosing circuit breakers that attempt to clear non-permanent faults, and intermittent loose connections in power wiring.

Short-duration interruptions have three sub-classifications, depending on the longevity of an interruption, including Instantaneous (1/2 to 30 cycles), Momentary (30 cycles to 3 seconds), and Temporary (3 seconds to 1 minute).

Similar to voltage sags, the consequences of short interruptions may cause the stoppage of your IT-sensitive pieces of equipment, loss of data, malfunction of data processing equipment, and unnecessary tripping of protective devices.

#3 Long-term Interruptions

Sustained interruptions or long-term interruptions stem from permanent faults caused either by natural phenomena such as storms and when a tree accidentally strikes lower power lines, or by human error.

The occurrence of long-term interruptions decrease the voltage supply level to zero for more than one minute. That’s why most electricians coin long-term interruption as a “long duration voltage variation phenomena.”

Long-term interruptions can cause an outage due to a failure of the system to function. As a result, it completely stops all devices and shuts down a customer’s facility.

#4 Voltage Spikes

A rapid buildup or decay of a magnetic field, creating energy into the associate circuit, may result in the formation of voltage spikes. Voltage spikes occur when its value suddenly peaks at a higher range than the nominal voltage value at a given time instant. The abnormal conditions of a voltage spike is synonymous to a voltage surge or a transient.

In the field of electronics, a transient explains how an operating point changes due to disturbances in parameters or any balance in electronic load. Due to the transient period, voltage spikes at a very high exponential rise. Being said, instruments like converters, breakers, and thyristors can withstand voltage spikes to avoid any device damage.

Moreover, voltage spikes could be the cause of the destruction of your electronic components, insulation materials, electromagnetic interference, and data loss.

#5 Voltage Swells


Voltage swells occur when a large electronic load, such as a large motor, has suddenly turned off,  and the voltage power line increases for a while. More often, voltage swell induced overvoltage, where its longevity of power loss lasts longer than a minute.

The International Electrical Commission suggests that the standard of voltage swells has a short duration between a few cycles to 1 minute, as it increases its supply voltage between 1.1 per unit and 1.8 per unit at rated power frequency.

You should be aware of the dangers of voltage swells, as results to your data loss, abnormal flicker of your lighting and screens, and damage of sensitive equipment like computers.

#6 Harmonic Distortion

A harmonic distortion best expounds the interference in an AC power signal, where it stems from the changes in frequencies within the electrical distribution system. Nonlinear loads cause the formation of harmonics in an electrical system, drawing short bursts of current not prop

Harmonics are the shape or characteristics of a voltage or current waveform relative to its fundamental frequency. Meaning, the power source comes from smooth sinusoidal waves. In other words, harmonics is the by-product of the deviation of waveforms from a sine wave shape.

In worst-case scenarios, a harmonic distortion causes the misoperation of electronic loads, mechanical fatigue of motors, increased noise, and possible insulation failure of transformers, and the inability to fully load the motor. Hence, it requires you to have higher costs in repairing inefficient equipment for your continuous operations.

#7 Voltage Fluctuation

Voltage fluctuation is a continuous and regular change in the voltage of your devices or appliances that require a higher load to function. The implications of voltage fluctuation to your device are synonymous with the effects of an Undervoltage. Usually, voltage fluctuates when the lights of your device manifest an abnormal flicker or to glow brighter.

There are various causes of a voltage fluctuation, including poor supply of electricity, natural causes, wiring issues, and interferences. In your day-to-day electrical consumption, voltage fluctuation may occur when there is an improper wiring, where your electrical wires cannot hold the necessary amount of power required for the entire building. Also, ungrounded outlets may lead to heavy leakage of electricity.

Further, voltage fluctuation can cause extreme and heavy damage to your life and property. If you have any faulty electrical appliances, it may result in a fatal electric shock.

#8 Electronic Noise

The result of random electrical signals attempting to get an unwanted entry into circuits is known as an Electric Noise. It is a type of noise that disrupts an information-carrying signal. In a practical sense, the signal and data circuits are potentially vulnerable for electronic noise since they function at fast yet low voltage levels.

There are two sources of electronic noise – the external source and the internal source. The external noise refers to the environmental factors like the atmosphere and industrial noise. On the contrary, the internal noise refers to the receiver’s components while functioning, such as the Johnson Noise, Shot Noise, Transit-Time Noise, and Miscellaneous Noise.

The consequences of electronic noise are not grave and damaging. It only causes minimal disturbances in sensitive electronic equipment.

#9 Voltage Unbalance


The Institution of Electrical and Electronics Engineers define voltage unbalance as the ratio of negative or zero sequence components to the positive sequence component. It measures the voltage differences between the phases of a three-phase system.

This type of power quality problem stems from mechanical stresses in motors due to lower torque output, higher current in motors and three-phase rectifiers, and unbalance current flow in three-phase wye systems.

The consequences of a voltage unbalance show a complication to all polyphase loads. Meaning, it results in a cumulative and permanent damage to the motor caused by heat. Further, it may lead to increased vibration and mechanical stress, motor overheating, and permanent failure of transformers and three-phase motors.

Key Takeaways

Power quality explains the interaction of electrical power with electrical equipment. It identifies the difference between the expected and actual performance of an electric power. Hence, it is the backbone of every resolution to electrical problems.

That’s why key industries and commercial processes invest in power quality monitoring programs to avoid any power disturbances, which could affect their regular production.

To avoid any expensive costs in repairing and mending your damaged devices, here are the nine most common power quality problems:

  1. Voltage Sags
  2. Short-duration Interruptions
  3. Long-term interruptions
  4. Voltage Spikes
  5. Voltage Swells
  6. Harmonic Distortion
  7. Voltage Fluctuation
  8. Electronic Noise
  9. Voltage Unbalance

Indeed, a good power quality equates to high-end productivity, low rate of equipment failure, and minimal damage costs.


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