Arc furnace

Arc furnace is used for high degrees of heating. When an air gap is subjected to a very high voltage, the air gets ionized due to electrostatic force. This basic idea is employed in arc furnaces. The ionized air has conducting nature. Due to this, a current starts flowing through the air gap in the form of continuous spark. This spark is known as arc. As electrodes, either graphite or carbon is used. There are two varieties in this category. They are direct arc furnace and indirect arc furnace. In a direct arc furnace, charge acts as another electrode. Very high temperature can be achieved here since the arc is directly in contact with the charge. Usually size of this type of furnace ranges from 5 to 10 tonnes and power factor is around 0.8. This type of furnace is commonly used in steel production industry but not all recommended for melting processes. In an indirect arc furnace, arc is produced between two electrodes and the heat is transmitted to the charge by radiation. Here one single-phase supply is enough since only two electrodes are used. It’s difficult to attain very high temperature in an indirect arc furnace.