Power Quality Analysis for Harmonic Limited

The increased use of nonlinear electronic equipment has become a concern in most utility power systems. Nonlinear loads draw current discontinuously during the cycle of the input voltage waveform and produce low power factors when harmonics are taken into account. This increases line current and can limit the available capacity of branch circuits. Moreover, harmonic currents can cause heating in utility and facility transformers. Modern personal computers (PCs) and other information technology (IT)- based equipment utilize "switching regulators," or switch-mode power supplies (SMPSs), to convert utility ac power to regulated dc power. SMPSs are typically single-phase nonlinear devices that generate high 3rd harmonic current.