Top 10 Power Quality Problems (explanation, consequences & solutions)

Here’s a very nice short articles about the 10 power quality problems you electrical engineers all face! Give your impressions, which one is the worst to handle?


Before we move on to the top 10 power quality problems, let us first understand what power quality is, and why it has become the most vulnerable issue pertaining to power supply in the recent years.

Power Quality: It can be defined as a measure of voltage parameters that synchronize with the phase and allow electrical systems and equipment to function normally without causing any loss to their performance and durability. Simply put, power quality is a factor that determines how fit and safe the electricity is, from a consumer’s point of view.

Why it has become the most vulnerable issue?

Though, power quality has been an issue with electrical power since it was invented, it has become a very popular issue in the recent years. This is because, most of the data losses, computer reboots and malfunctioning of the electric devices are due to inferior power quality.

Following are the top 10 power quality problems ranked according to their impact on electrical systems and devices, with first one being the most vulnerable cause:

1.Voltage Sag


  • Explanation: This is the most common problem in which voltage drops from 10 to 90% of the normal power frequency voltage. This may last up to one minute.

  • Consequences: Malfunctioning of computers, IT equipment, electromechanical relays and electric rotating equipment, etc.

  • Appropriate solutions: Using voltage regulators, power conditioners, uninterrupted power supply systems can prevent the above mishaps.

2. Short Interruptions

Short Interruptions

  • Explanation: Short interruptions occur when power supply is completely nullified for a few milliseconds, and sometimes, up to two seconds.

  • Consequences: Protection devices get tripped, inefficient data processing or loss of data, sensitive electric equipment may stop (PC’s, ASd’s, etc.)

  • Appropriate solutions: Using power conditioners and uninterrupted power supply systems can prevent the above mishaps.

Long Interruptions

Long Interruptions

  • Explanation: Long interruptions occur when power supply is completely stopped for more than two seconds.

  • Consequences: All electric equipments stop functioning.

  • Appropriate solutions: Using Gensets, Power generators, solar inverters, electric home inverters, etc., can provide temporary solutions.

4. Voltage Spike


  • Explanation: This takes place at a lightning speed. A sudden spike in the voltage may occur due to lightning strikes, during thunderous storms or due to sudden connection/disconnection of heavy loads from the mains. These spikes generally last only for few microseconds.

  • Consequences: Destruction of highly sensitive components such as microprocessors, insulating coils. Can also cause electromagnetic interferences (EMI’s).

  • Appropriate solutions: Voltage regulators, UPS can save your electric equipment from low to medium voltage spikes.

5. Voltage Swell

Voltage Swell

  • Explanation: Voltage swell is defined as a brief increase in the voltage for a few seconds. This is generally caused due to defective transformers, inefficient power sources or sudden operation of heavy loads.

  • Consequences: Lights and screen displays flicker, data loss, sensitive equipment may stop or get permanently damaged.

  • Appropriate solutions: Voltage regulators, power conditioners and UPS can prevent your devices from voltage swell.

6. Harmonics


  • Explanation: Harmonic distortions are associated with both voltage and current waves in the sinusoidal form. Though voltage harmonics are present, most of the harmonics are caused as a result of current distortion. And prominent electric distortion takes place due to the presence of variable electric loads on the power system, also known as non-linear loads.

  • Consequences: Increased resonance, overheating of equipment as well as cables, EMI’s, tripping of protectors, etc.

  • Appropriate solutions: Using passive filters, active filters (costly option), delta-wye transformers, k-rated transformers can prevent different types of harmonic distortions. Also, increasing the size of conductors can help reduce impedance and thus the harmonic distortion.

7. Voltage Fluctuation

Voltage Fluctuation

  • Explanation: Arises due to oscillations in voltage value and amplitude, when modulated by signal waves having frequency less than or equal to 30 Hz.

  • Consequences: Lights and screen displays flicker, data loss

  • Appropriate solutions: You can avoid voltage fluctuations using voltage regulators or power conditioners.

8. Noise


  • Explanation: Noise comes into picture when the frequency of a power system is superimposed by signals having higher frequencies.

  • Consequences: Simple disturbances in IT and electronic equipment (no serious damage occurs)

  • Appropriate solutions: Noise can be reduced using proper bypassing ad filtering techniques.

9. Voltage Unbalance (VU)

Voltage  Unbalance (VU)

  • Explanation: Voltage unbalance is a result of frequency variation in a three phase power supply which arises due to unequal differences between the phase-angles of the three respective voltages.

  • Consequences: As a result negative sequence may be inducted into the system which can be harmful to the phase loads (most vulnerable equipment in such cases is, three phase induction motor).

  • Appropriate solutions: Using PWM converter as a STATCOM controller or as an active filter can reduce voltage unbalances considerably.

10. Brownouts


  • Explanation: Brownout is a continuous low voltage power supply state. It occurs sparingly in summers (or when the demand of power outweighs the supply).

  • Consequences: Inefficient data processing or loss of data and malfunctioning of electrical equipment.

  • Appropriate solutions: Voltage regulators, UPS and power conditioners can save your electric equipment from brownouts.


Since the invention of electricity, there have been problems regarding power quality. Many measures were taken to control loss of power when distributed over long distances, such as attenuation and polarization. Unfortunately, even now, the problem persists.

However, one can reduce; if not entirely eliminate the power quality problems, with the above mentioned electric equipment as a solution for each problem.

This was the top 10 of the worst power quality problems that you can face. Give your impressions and tell us which one is the worst to handle to you?


  • Thank you for this resource. I have a number of new recruits to our team of electrical contractors and electronic engineers and we have been showing similar resources to them. I will be sharing your article with them. Again thank you.

  • why it sometime occurs voltage swell in HV,MV transmission line?example,my MV standard 22KV, it move up and down as soon as around 5mm ,from 16Kv to over 25KV on volt matter .

  • This save our glob definatly , because I know the tremendous power loos in power utility companies in India . by only having control on quality power we can save about 20% of our energy at least in India.

Leave a Comment