Arc-furnace loads on long transmission lines

LARGE electric arc furnaces are loads which frequently introduce special technical problems when served from a central-station system. The fluctuations in the load taken by the furnaces are violent, and this characteristic combined with the inherently low power factor of this type of load results in a serious flicker problem. The low power factor also may require power-factor correction, in order to maintain a reasonable voltage level and reduce transmission losses. A further complication is that the arc is an excellent source of higher-harmonic currents and voltages. Where the load or the supply lines are close to telephone circuits, this may necessitate special measures to prevent telephone interference.