A study of harmonics at Dacotah Cement

The major objective of the study of harmonics at Dacotah Cement plant (USA) power systems was to verify that the addition of passive harmonic filters on each of three variable frequency drives resulted in a reduction in the fifth harmonic and total harmonic distortion (THD) as specified. A secondary objective was to identify the types of electrical equipment in the plant susceptible to the effects of harmonics in order to recognize if the harmonics study needs to be expanded to include the entire plant. Older electrical distribution systems are the most susceptible to damage because the motors, transformers, cables and circuit breakers were not sized to handle the eddy currents and skin effect due to the harmonic distortion introduced by the many types of nonlinear loads available today. Lower energy and maintenance costs are the major benefits of a plant wide harmonic study