What is Power Quality?

The ‘Quality’ of electrical power may be described as a set of values of parameters, such as:

Continuity of service

Variation in Voltage magnitude

Transient Voltages and Currents

Harmonic content in the waveforms

In its broadest sense, power quality is a set of boundaries that allows electrical systems to function in their intended manner without significant loss of performance or life. The term is used to describe electric power that drives an electrical device and the device’s ability to function properly with that electric power. Without the proper power, an electrical device may malfunction, fail prematurely or not operate at all. There are many ways in which electric power can be of poor quality and many more causes of such poor quality power. The "Clean Electrical Power" myth is one that has been circulating quite dramatically for a number of years now and is becoming increasingly dangerous in this postmodern world of microprocessor-controlled everything. From the Microwave Oven to the Microwave Tower and the VFD to the PLC; virtually everything in today’s world is using microchip-based technology. There are a multitude of independent studies, research reports and business reports to finally kill off this myth and awaken the public to the true need for Power Quality Products. We submit the following factual information, in no particular order, designed to once and for all lay to the rest the Urban Myth of "Clean Electrical Power". Plant Services Magazine reported that 35% of lost production hours could be attributed to transient voltage problems.

TRW computer services firm - discovered that greater than 40% of their service calls were NTF, power related problems.
Business Week magazine call power related problems a $26 Billion Dollar a year problem.
Electrical Contractor magazine notes that greater than 70% of dirty-power problems can be related to wiring, grounding and equipment in nearby panels, locations or buildings. Mid America Banner reports a study in which 29% of Copier service calls could be and were eliminated with the application of quality surge suppression devices. The Electric Utility industry sustains over $1 billion a year in costs for damaged equipment and lost revenue from lightning incidents.
Lightning-induced outages cost the telecommunications industry $100 million per year.
A study composed recently by Interpose Inc. and Microsoft analyzes the Total Cost of Operation for Windows based systems. They have dissected the cost of operations into Hardware and Software, Management, Support, Downtime and several other items. Their research indicates the TCO for the desktop PC runs in the neighborhood of $7250 per year! The most concerning figure is the 20% allocation of the TCO to downtime! If we extrapolate 50% of that cost as being power related then approximately $725 of the annual cost of operation on a networked PC can be attributed to poor power. A recent IBM study showed that the typical computer is subject to more than 120 power problems per month.
Is it any wonder that the power quality products industry is growing at a rate of close to 20% annually. The need has never been greater, the awareness is continually growing and yet their are still small pockets of individuals who live under the misguided assumption that the electricity in their office, plant, lab or hospital is as clean as snow. In order to increase productivity and competitiveness in the global economy companies have to invest in computers, automated manufacturing systems, digital telecommunications networks, LANs and WAN's. Companies depend upon reliable performance and longevity of these investments. Yet, how often is this equipment connected directly to "street" power with no thought as to what goes on behind the outlet. The utility companies are being pressured to supply cleaner and cleaner power, when in reality 60-80% of all power disturbance events are created internal to the facility. It is not that the utilities are sending out dirtier power, it is that the equipment within the facility has become enormously sensitive and subject to even the slightest of power fluctuations. Many times causing data upset, over the long term cumulative damage and equipment failure.

It is often useful to think of power quality as a compatibility problem: is the equipment connected to the grid compatible with the events on the grid, and is the power delivered by the grid, including the events, compatible with the equipment that is connected? Compatibility problems always have at least two solutions: in this case, either clean up the power, or make the equipment tougher. Each of these power quality problems has a different cause. Some problems are a result of the shared infrastructure. For example, a fault on the network may cause a dip that will affect some customers and the higher the level of the fault, the greater the number affected, or a problem on one customer’s site may cause a transient that affects all other customers on the same subsystem. Other problems, such as harmonics, arise within the customer’s own installation and may or may not propagate onto the network and so affect other customers. Harmonic problems can be dealt with by a combination of good design practice and well proven reduction equipment. The evidence demands a verdict, only one logical conclusion can be drawn from this material. There really is a power quality issue to be concerned with, it negatively effects all electrical and electronic equipment, and neglecting the issue can and will add thousands of dollars of needless expense to the bottom line of your company.