Electrical power quality is routinely taken for granted by most industries irrespective of the fact that it is absolutely fundamental to the safety and operational integrity of the installation, without exception. Medium to large electrical variable speed drives; DC drives and AC variable frequency drives (VFDs) are fundamental to most operations.  However, their use significantly degrades the quality of electric power, increases equipment failure, and disrupts control systems, resulting in production losses and compromised safety.

US$100m’s are lost annually across industry, directly and indirectly, due to poor power quality, by industries often unaware of where the damage or disruption to equipment originates from. Some consequences of poor power quality can appear relatively minor (e.g. the repeated failure of control relays, VFD capacitors or electric motors) but are often expensive operationally.

Common mode voltage, a largely unrecognised EMC phenomenon due to VFDs, presents a constant and increasing threat of disruption to equipment, jeopardising operational integrity and safety. All this is happening in the background and most are unaware of the threat poor power quality poses to their investment and to the safety of their employees.

Unacceptable power quality can have significant impacts on safety, the productivity of operations and profitability. The cost of mitigation required to ensure prevention is only a tiny fraction of the possible financial losses. An acceptable level of power quality is now absolutely fundamental for safety and operational integrity of all industries worldwide and will be increasingly important in future. At the very least management should know they has no problems lurking ready to strike.

When was your installation last subject to a power quality audit ?



Power quality and harmonics have been a developing and growing concern as commercial and industrial installations have become more reliant on technology, the ever-increasing utilization of digital control systems, and the drive towards more efficiency. In recent years, harmonics from commercial and industrial installations have caused issues to supply networks, and authorities now require owners of large installations to take measures to limit harmonic distortion being imposed on to the utility grid network, and to protect their own internal power network.

Moreover, lack of true power quality monitoring facilities within the installations have refrained owners from realizing the adverse effects a bad power quality, noncompliance with standards and poor design has on the equipment within the installation as well as introducing background distortion into nearby facilities.

Causes of bad power quality

Internal Causes

  • 80% Originate from within an installation
  • Due to large equipment start or shut down
  • Improper wiring / Grounding
  • Harmonics
  • Bad design

External Causes

  • From Utility transmission & distribution System
  • Lightning strikes, equipment failure, weather conditions.

Common power quality issues

  • Overheated neutral
  • Lost productivity
  • Unscheduled downtime \ Interruptions
  • Light Flicker
  • Fast aging of equipment \ pre-mature failure
  • Equipment mal-function (Motors stall, PLC damaged, Computers crash, Reporting errors etc.)
  • Overheated transformers and motors
  • Lost productivity
  • Lost revenue
  • Unsafe work environment – lives at stake
  • Possible penalties from Utilities


  • According to Electric Light and Power Magazine 30% to 40% of all business downtime is related to Power Quality Issues.
  • Euro 150 Billion Poor Quality cost to European economy (Leonardo Power Quality Initiative)
  • 122-188 USD Billion losses due to outage and other PQ issues in US (EPRI)
  • Berkeley Lab Study Estimates $80 Billion Annual Cost of Power Interruptions … Research News, Berkeley Lab, February 2, 2005
  • $50 billon per year in the USA is lost as a results of power quality breakdowns …. Bank of America Report
  • A manufacturing company lost more than $3 million one day last summer in Silicon Valley when the “lights went out.” … New York Times January 2000
  • “A voltage sag in a paper mill can waste a whole day of production – $250,000 loss” … Business Week, June 17, 1996
  • Half of all computer problems and one-third of all data loss can be traced back to the power line … Contingency Planning Research, LAN Times


Common power quality issues can be seen below:

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Alternatively for common power quality issues relating to marine please click here and for oil and gas click here.