1. Arc furnace principle

As mentioned in the Introduction, the first industrial arc furnaces appeared in the early 20th century.

Initially, the Héroult furnace (figure 1 a) had two electrodes, each connected to one terminal of a DC or AC generator. Soon, it was equipped with three electrodes connected to a three-phase network.

At this time, another type of arc furnace was also widely used for steel melting: the Girod furnace (figure 1 b). This furnace featured a single top electrode, connected to one terminal of a generator, and several steel bottom electrodes, connected...