Neb. Utilities have fewer problems handling power demand from DC EAFs, Pritchard says. AC EAFs are more disruptive to the power grid. Nucor's mills are in rural areas where the power grid has less capacity. The 150-ton AC Fuchs fingershaft furnace began making steel in Nov. 1997. You can achieve the same results as a DC furnace with electrode consumption.
Some steelmakers believe that electrode consumption is lower in DC EAFs.
Minn. Gallatin Steel reduces electrode consumption at its twin-shell DC furnace from NKK and MAN GHH by torquing the electrodes, or screwing them together tightly. Torquing prevents joints from becoming too loose or opening up. Loose joints prevent an adequate amount of current from passing through the body of the electrode. This saves one pound of electrode consumption per ton of steel, says Chris Williams, manager of steelmaking at the mill. DC furnaces have longer arcs and tend to have problems with their roofs' water-cooling system, Williams says.