8. Connecting the arc furnace to the mains

8.1 Disturbance problem

The essentially unstable nature of the electric arc makes the arc furnace a disruptive element of the power supply network, in that it calls up unbalanced currents on all three phases, with a wave whose shape is very different from a sinusoid, hence the production of harmonics, and sudden variations in intensity.

The latter phenomenon causes rapid voltage variations, leading to a spectral composition of frequencies in the 0.5 to 25 Hz band. These voltage variations are particularly noticeable in the luminous flux of incandescent lamps, creating a flickering effect that can become intolerable for other users [33] .

The phenomenon is all the more...