The Valve Effect of an Electric ARC and Problems in Controlling Electric-ARC Furnaces

The reasons for the existence of constant components of current and voltage in electric-arc furnaces are examined. It is noted that the accuracy with which the constant component of arc voltage is evaluated is strongly affected by the method used to sample the voltage signal. Results are presented from experimental studies of characteristics of the electric arc on a laboratory unit. It is shown that the magnitude of the constant component of the voltage on the electrodes depends on the constant component of the electrodes' current. A method is described for determining the constant component of the arc voltage based on values of the constant components of electrodes' current, voltage, and resistance. It is shown that it is best to use the method of dynamic volt-ampere characteristics for real-time monitoring of the parameters of the valve effect. Here, the quantity chosen as the controlled parameter is not the constant component of the arc voltage but the difference in its steady-state values.