We continue a two-part series on power quality and harmonics in AC electrical systems with an overview on how harmonics affects induction motors and electronic motor control devices. Specifically, we'll focus on variable frequency drives and some of the methods used to correct these problems. Harmonics from non-linear loads can impact the operation and proper function of all electrical devices that utilize induction, including transformers and motors. Examples of nonlinear loads include battery chargers, electronic ballasts, variable frequency drives, and switching mode power supplies. As non-linear currents flow through a facility's electrical system and the distribution-transmission lines, additional voltage distortions are produced due to the impedance associated with the electrical network. At harmonic frequencies, one of the major impacts of the harmonic current and voltage to induction motors and transformers is increased heat because of the increased loss of iron and copper. This causes an increase in operating temperature with motor efficiency also negatively affected.
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