Protection arrangement against excess arc-currents.

摘要

Device for protecting against excessive arc currents crossing the electrodes (5) of an arc furnace (2) powered by an electrical network (1) via a furnace transformer (4). This protection device comprises a coordinator (9) a first setpoint of which monitors the intervention of a position regulator (8) controlling a motor (7) for adjusting the position of the electrode (5) to the arc impedance value imposed, and the second setpoint of which triggers the automatic intervention of a normally saturated transducer (6) inserted in series with the primary of the furnace transformer (4) in order to limit the current crossing the electrode (5) to the threshold fixed by this second coordinator (9) setpoint. This device further comprises an order repeater (10) which in collaboration with the coordinator (9) and the position regulator (8) triggers the high-speed return of the electrode to the phase in which the desaturation of the transducer (6) and the disappearance of the arc are detected simultaneously.