Light flicker in relation to power-system voltage fluctuation

The supply to fluctuating loads is often restricted more by considerations of voltage fluctuation than by the thermal rating of the supply-system equipment. Results, both of laboratory tests and a study of flicker complaints, have been used to find the relation between voltage fluctuation and light flicker. The spread of opinions of different observers has been studied, and the probable effect of increasing or decreasing a voltage fluctuation can be predicted. The ratio of the impedance of an arc-furnace installation to that of the supply system is related to the occurrence of complaints of flicker. Arc-furnace-voltage fluctuations have been found to add according to a root-mean-square law. A method of measuring irregular voltage fluctuations is described which will be used to study the variable fluctuations produced by single and multiple arc-furnace installations. Remedial measures are discussed.