Investigations of voltage flicker in electric arc furnace power systems

Operation of rapidly varying loads such as AC and DC arc furnaces in large industrial power systems will cause voltage flicker on the utility system. System planning will help in determining the available short-circuit duty at the point-of-common-coupling to keep the voltage flicker within acceptable limits. Perceptible flicker limit curves are useful in determining the amount of flicker in a system. Short-circuit voltage depression calculation is one technique to estimate the amount of expected flicker in a system. On-site field tests with equipment that will accurately capture multiple frequencies will aid in measuring the existing voltage flicker. The authors discuss flicker estimation and field tests as well as harmonic filter tuning effects on voltage flicker. The ultimate determination whether unacceptable voltage flicker exists in a system will be complaints from customers served by the utility system actually experiencing objectionable or noticeable flicker