Governing Power Quality

When most people think of the word “government,” the word “regulation” is usually close behind. The government regulates the speed that you can drive on the highways, how much income tax you pay, how much pollution a factory can emit, even which drugs can be sold (legally). Yet there is no federal regulation concerning power quality in the United States. There is no all-encompassing regulation cover what quality of supply the utilities must provide, nor how a consumer can use that electricity, even if it creates “pollution” on the electrical distribution system that affects their neighbors.

There is an American National Standard (ANSI C84.1) that established nominal voltage ratings and tolerances for electric AC power distribution above 100V. The two measuring points established are at the service entrance (the point of common coupling where the utility system meets the consumer’s electrical system), and the point of utilization, which is where equipment within a facility uses the electricity. In summary, ANSI C84.1 expects that the voltage at the service entrance will be +/-5 percent of the nominal voltage, and the voltage at the outlet will be –13 percent to +6 percent of nominal. There are exceptions and variations and the like, but that is the gist. However, it is still up to the individual Public Utility Commission (PUC) whether or not to adopt such voltage regulation requirements. In addition, this refers to the steady-state, long-term voltage levels, not the voltage during disturbances, such as sags and swells and transients, that characterize PQ phenomena.

There is no federal standard on the amount of harmonic “pollution” that a consumer can back-feed onto the utility system, nor the maximum harmonic content that can be in the voltage provided to a consumer by the utility. The amount of voltage fluctuation that results in light flicker is well documented with procedures for measuring, but nothing that says how much flicker is too much. Transients know no federal rules, nor do they have to, as there aren’t any regulations concerning such. The regulation of such in the United States has been for the most part, a matter between the utility and the consumer and the PUC.

This is not the case in many other parts of the world. The IEC has established standards for how you measure such (IEC 1000-4-X series of standards) as well as the limits for susceptibility and emissions (IEC 1000-2-X and 1000-3-X). These are often adopted into law in Europe and other parts of the world. In fact, there is even a standard (IEC 1000-4-30) nearing adoption which deals specifically with how to measure power quality phenomena.

Not that I am a proponent of regulation. It reminds me of words from the song by the Five Man Electric Band: “Signs, signs, everywhere’re signs. Do this, don’t do that, can’t you read the signs?” The European propensity towards regulation might be remnants of their feudal society origins, whereas the feelings in the U.S. carry on from its origins, “Live Free.” However, it often leaves the “enforcement” of compliance and compatibility to the courts and lawyers with minimal if any technical understanding of what are acceptable and practical limits.

There are a number of documents in the United States that are very useful in the power quality field. One organization at the forefront of the standard-making process is the IEEE (Institute of Electrical and Electronic Engineers). The IEEE Standard 1159 covers monitoring the quality of electrical power, and new work covers data acquisition, characterization and data file formats. IEEE 519 is probably the most quoted PQ standard (actually a “recommended practice,” like many of the other IEEE PQ documents), and covers harmonics. IEEE 1346 addresses the compatibility between the equipment and the supply. There are documents being developed on emergency and standby power (P446), custom power (P1409), distributed resources and electric power systems interconnection (P1547), flicker (P1453), and voltage sag indices (P1564). And one shouldn’t forget the IEEE/ANSI “color book” series, especially the Emerald Book (IEEE Standard 1100) on Powering and Grounding Sensitive Electronic Equipment.

The National Fire Protection Association (NFPA) is the keeper of the National Electric Code (ANSI/NFPA 70), which is adopted as law by many local building code authorities. This document has important information on how to create safe electrical systems within a facility, but not necessarily how to make them suitable for the power quality needs of the equipment within the facility. NFPA 70B is a recommended practice that addresses the maintenance of electrical equipment, and it has a chapter dedicated on how to measure and resolve power quality related problems.

There are some documents generated from various federal government agencies that do apply to power quality. The military has documents from the Army Corps of Engineers on the electrical system for military bases. Mil-Std-1399 covers shipboard power and Mil-Std-704E covers aircraft power. Perhaps the oldest is the FIPS Publication 94 for Guidelines on Electrical Power for ADP Installations. Other industry specific organizations have their own standards, such as SEMI F47 and F42, developed by the semiconductor industry.

Lack of regulated power quality in the U.S. is both a blessing and a curse. But making yourself aware of the wealth of information available can help assure that a facility operates at peak productivity.

BINGHAM, a contributing editor for power quality, can be reached at 732.287.3680. 


About the Author

Richard P. Bingham

Power Quality Columnist
Richard P. Bingham, a contributing editor for power quality, can be reached at 732.287.3680.

Stay Informed Join our Newsletter

Having trouble finding time to sit down with the latest issue of
ELECTRICAL CONTRACTOR? Don't worry, we'll come to you.