Procedure and device for measuring the instability of an arc in an electric furnace for the treatment of liquid metals

摘要

According to this process and this device: a signal representing the derivative of the intensity of the current in the arc is sensed, the sensed signal is amplified, the amplified signal is directed simultaneously into two band pass filters (6, 7) respectively having a high frequency broad band (6) and having a narrow band centered on a low fundamental frequency (7), the signals emanating from the filters (6, 7) are transmitted to effective value extractors (8, 9), by means of a divider module (11) an energy signal is formulated, which is proportional to the ratio of the effective value of the signal emanating from the broad band filter (6) and the effective value of the signal emanating from the narrow band filter (7), and the proportional energy signal obtained is displayed on a scale (12), where it is expressed as a percentage, this percentage being indicative of the behaviour of the arc, signifying the formulation phase. The signal supplied by the display element (12) permits the regulation of the furnace in real time by the control operator.