Harmonic distortion is typically introduced into utility lines through customer non-linear loads installed in various types of manufacturing facilities.
Such equipment consists of variable frequency drives, uninterruptible power supplies, and other types of rectifiers used to convert power from AC to DC.
Total Demand Distortion (TDD) is defined in the IEEE 519 Standard as “The ratio of the root mean square of the harmonic content, considering Harmonic components up to the 50th order and specifically excluding interharmonics, expressed as a percent of the maximum demand current.
Harmonic components of order greater than 50 may be included when necessary.”
The Total Demand Distortion is shown with the following formula...
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