Harmonic currents generated by nonlinear loads are becoming a pervasive problem. A “nonlinear” electrical load is a load on the electrical utility that requires a current from the utility, whose electrical waveform is non-sinusoidal. Computers, fax machines, printers, electronic lighting ballasts, and variable-speed drives (vsd’s) are prime examples of nonlinear loads that are capable of generating harmonic currents.
As electronic hardware proliferates within the workplace, this equipment is more susceptible to, and sometimes the cause of, a building’s power-quality problems. Excessive distortion is manifested as voltage fluctuations and non-sinusoidal supply voltages within the building’s power distribution grid. While power-quality issues have been given little attention in the past, today it is widely recognized that current distortion must be controlled to protect the building’s power system and electronic office equipment. A building’s electrical system can tolerate only a limited amount of current distortion, and vsd’s can contribute to the problem.