AUTOMATIC RAPID MELTING SYSTEM AND ITS APPLICATION FOR ARC FURNACE

摘要

An electric power supply program is set for controlling a steel making arc furnace. According to this program, a steel melting period is divided into a plurality of successive melting sections in each of which a predetermined total of electric power is to be supplied to the arc furnace at an optimum power level. The electric power which is actually consumed is integrated during each of said melting sections. Power level is switched from the optimum power level programed for one of said melting sections to that programed for the next section when the amount of electric power consumption actually integrated in said one melting section becomes equal to the predetermined total of electric power programed for said one melting section, thereby a melting electric power is supplied to the arc furnace at the optimum power level programed for said next melting section. A power factor program is also set. According to this power factor program, a melting electric power is to be supplied to the arc furnace with a predetermined power factor to provide an optimum length of arc for each of said melting sections. The power factor is maintained at the predetermined optimum value for each of said melting sections by controlling the current into the arc furnace by use of the deviation of the actual power factor from the power factor programed for the section. Moreover, the total electric power Y which is necessary in melting the charge of steel material is tentatively determined. First electric power Y1 which is consumed for each of a plurality of definite, ever increasing periods from the beginning of melting operation is determined and second electric power Y1 per unit time consumed just before the end of each of said definite periods is determined. The value X of remaining period of time which is expected to be taken before the termination of the melting operation is estimated from the following equation, X = (y - Y1)/ Y1, and the value of X is indicated at every estimation to inform the operator of the remaining period of time from the end of each of said definite periods to the termination of the melting operation.