Maybe it is because they are rarely seen by the human eye or because the proliferation of surge protector strips makes everyone feel immune, but transients still exist and can wreak havoc with electrical equipment.
While few would argue about of the wealth of information on the Internet, there isn’t a mechanism for qualifying its accuracy. Basically, anyone can post anything. Even such peer-reviewed sites as Wikipedia can fall short of the facts. A relatively simple concept in power is a good example.
I often give my power quality (PQ) 101 course to new engineers or salespeople. This introduction starts with the basics: an overview of PQ phenomena based on IEEE 1159 Table 4.2 followed by Ohm’s and Kirchhoff’s laws and how they apply to power quality.
The electrical energy usage in most industrial and commercial facilities follows a reasonably consistent pattern from week to week, so a one-week monitoring program usually is adequate to determine what can be done to save 10–20 percent on electric bills.
When considering power quality disturbances or the quality of the electrical supply, phenomena such as rms variations (sags, swells and interruptions), harmonics, unbalance and flicker usually come to mind.
There is an old saying that liars figure and figures lie, which implies that the truth can be a challenge to discern from both people and data. At a recent standards-making conference, I encountered some examples of this concept that seemed worth sharing.
A customer recently called me about the information on his power quality monitor screen. He said about a dozen different events were showing up, but the lights had just blinked once. He wanted to know what all of the other nonsense was supposed to tell him.
A hot summer’s evening usually begets long lines at the local ice cream shop. Recently, at one such shop, the line grew extra long when the cash registers and credit card machines mysteriously powered off and on.
The blinks and flickers referred to here can best be described as “voltage fluctuations on electric power systems [that] sometimes give rise to noticeable illumination changes from lighting equipment.” The Institute of Electrical and Electronics Engineers (IEEE) standard that covers this is about to
When one of the coaches was asked before the “big game” what would be the key to his team’s success, he said, “executing the fundamentals.” While blocking, tackling, passing and catching may work for football, Ohm’s and Kirchhoff’s Laws are fundamental to understanding any power quality issue.
An estimated 3 percent of every sales dollar in the United States is spent on solving power quality (PQ) problems, according to Christopher Forthaus, senior product manager, test division, Ideal Industries Inc., Sycamore, Ill.
This month, we honor perhaps the most notable person in the history of the power quality (PQ) industry, often called the father of PQ monitoring: Abraham I. Dranetz. Some of us knew him as Abe, and others knew him as Mr. Dranetz.
The categories or labels used to describe the plethora of power quality phenomena that can occur on electrical systems have not changed much in the past decade or two. Measurement methods and acceptable limits for most systems have changed.
In attempting to explain to a colleague why we care about negative sequence components, I tried to follow the guidance that Bob Lawrie, another member of the NFPA 70B Electrical Equipment Maintenance committee, offered to me many years ago: never use a formula in an article.
Lightning is the biggest cause of damage and destruction of electrical and electronic equipment in industrial facilities, commercial buildings and homes, as stated in the 2008 report by the U.S. National Lightning Safety Institute.