Power Quality is a term used to broadly encompass the entire scope of interaction among electrical suppliers, the environment, the systems and products energized, and the users of those systems and products. It is more than the delivery of "clean" electric power that complies with industry standards. It involves the maintainability of that power, the design, selection, and the installation of every piece of hardware and software in the electrical energy system. Stretching from the generation plant to the utility customer, power quality is a measure of how the elements affect the system as a whole. (2)
Power Quality has been a problem ever since the conception of electricity, but only over the last two decades has it gotten considerable attention.
The `80s brought about the move of computers from the office to the home and to just about everywhere else. The '90s brought the network revolution and ever increasing equipment capability. More importantly, both of these decades brought the potential for more interference. (1)
Today's environment brings with it the possibility of many new problems. With ever increasing integrated circuit densities, faster processor speeds, and increasingly sensitive equipment, the chance of interference occuring will undoubtedly rise unless something is done. (1)
With all this new technology, we are still faced with many of the basic power quality problems that have been with us for years: loose connections, netraul to ground bonds, and poor construction practices. In fighting these problems, the screwdriver can be a very useful tool. (1)
Power Quality affects everyone, and there are hundreds of examples of power quality problems and solutions. One simple example of a power quality problem is the dishwasher in the kitchen disrupting the computer in the den. Converse;y, if a bottle manufacturing plant is able to continue operating as high winds cause intermittent arcing of overhead lines, the power quality industry has achieved its goal.
Sags - Sags are under-voltages on the power system and commonly caused by power failures, downed lines, utility recloser operations, and storms. They can be corrected by using backup power sources such as UPSs, generators or similiar voltage restoration technologies.
Surges - Surges are caused by over-voltages resulting from lightning, switching on the utility power system and other causes without forewarning. Surgesnormally can be filtered out of the power system at the customer level.
Harmonics - Harmonics result from distortions to the voltage and/or current sine waves. Harmonics are commonly caused by ASDs, industrial processes, certain electronic loads, and wiring connections. Harmonic problems often cna be corrected by filtering or resizing power system components.
Wiring and Grounding - Wiring and grounding problems come in the form of intermittent network failures, buzzing sounds (corona effect), scorched insulation, intermittent voltages at equipment, and burned panel or junction boxes. Wiring and grounding problems can often be fixed by checking to see that everything is properly connected and that there are no bad wires being used.
The need for solutions to power quality problems grows with every passing second. Currently many projects are under way and they are loooking at how to collect data to find and analyze power quality problems. Presently, the analysis ;of power quality problems is often difficult due to the fact that the source of a problem can be a few feet away in the form of a loose connection, or a hundred miles away in the form of a power system fault. If we look back at the stated power quality problems of sags, surges, harmonics, and wiring and grounding, one can see that each one has possible solutions to correcting these problems.
If you would like to learn more about power quality, Electrotek Concepts, Inc. and Energy-One are two companies that can provide you with some very helpful information. Furthermore, there is a Power Quality Network, run be Electrotek, that you can subscribe to so that you can get the latest information about power quality.
Power quality terms today must have one meaning. The need for this arises out of the interaction between suppliers and consumers. They must be able to communicate with each other. Therefore, the Glossary of Power Quality Terms and the Power Quality Terms and Definitions pages are very handy in answering any questions about specific terms.
(1) B. Loni, PowerCET; D. Kriess, Kriess Johnson Technologies; W. Shanner, Long & Associates; and Power Quality Staff. Power Quality: Yesterday, Today and Tomorrow. Power Quality Assurance Jan/Feb '95. p 13 & 15. (2) Call For Papers. Power Quality Assurance Jan/Feb '95. p 74.
Any questions or comments that you may have, please e-mail Scott Sander at sasc@ksu.ksu.edu or Larry D. Hafner, Jr. at ldh@ksu.ksu.edu.