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CHAPTER 8Motors, Generators, and Controls > Harmonic Mitigation - Pg. 249

Motors, Generators, and Controls 249 might include [38] power rectifiers, variable speed drives, switch-mode power supplies, and uninterruptible power supplies. The current and voltage harmonics generated by the use of non-linear devices can also be introduced into the utility system service point providing power. Harmonic distortion damage can be mitigated on the customer electrical distribution system feeding non-linear electrically controlled equipment by the use of harmonic filters, line reactors, etc. IEEE 519, IEEE Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems was developed to assist in the prevention of the introduction of customer generated harmonic voltage components into a utility system at the customer service point. That standard limits [39] the maximum voltage total harmonic distortion (V THD ) for general electrical systems to 5%, with no more than 3% for any individual harmonic component. Hospitals, airports, and other specialty applications are limited to a V THD of 3%. On dedicated systems in which there are no non-linear loads, IEEE 519 allows a V THD of 10%. Voltage total harmonic distortion (V THD ) is defined by IEEE 519 as the ratio of the root-sum-square value for the harmonic content of the line voltage to the root-mean- square (RMS) value of the fundamental voltage V 1 . The mathematical relationship for