Abstract 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.
A method of controlling a steel making arc furnace including the steps of: a. setting an electric power supply program according to which a steel melting period is divided into a plurality of successive melting sections, a predetermined total of electric power being supplied to the arc furnace at an optimum power level in each of said melting sections; integrating the electric power actually consumed during each of said melting sections; and switching power levels from the optimum power level programmed for one of said melting sections to that programmed 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 programmed for said one melting section, melting electric power thereby being supplied to the arc furnace at the optimum power level programmed for said next melting section; b. setting a power factor program according to which 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; and maintaining the power factor at the predetermined optimum value for each of said melting sections by controlling the current into the arc furnace as a function of the deviation of the actual power factor from the power factor programmed for the section; and c. determining tentatively the total electric power Y which is necessary in melting the charge of steel material; determining a first electric power Y1 which is consumed for each of a plurality of definite, ever increasing periods from the beginning of the melting operation; determining a second electric power Y1 per unit time consumed just before the end of each of said definite periods; estimating the value X of the remaining period of time which is expected to be taken before the termination of the melting operation from the following equation, X (Y-Y1)/Y1 ; and indicating at every estimation the value of X 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.
Claim 2
Independent Claim
355 words
A method of controlling a steel making arc furnace including the steps of: a. setting an electric power supply program according to which a steel melting period is divided into a plurality of successive melting sections, a predetermined total of electric power being supplied to the arc furnace at an optimum power level in each of said melting sections; integrating the electric power actually consumed during each of said melting sections; and switching power levels from the optimum power level programmed for one of said melting sections to that programmed 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 programmed for said one melting section, melting electric power thereby being supplied to the arc furnace at the optimum power level programmed for said next melting section; b. setting a power factor program according to which 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; and maintaining the power factor at the predetermined optimum value for each of said melting sections by controlling the current into the arc furnace as a function of the deviation of the actual power factor from the power factor programmed for the section; and c. determining tentatively the total electric power Y which is necessary in melting the charge of steel material; determining a first electric power Y1 which is consumed for each of a plurality of definite, ever increasing periods from the beginning of the melting operation; determining a second electric power Y1 per unit time consumed just before the end of each of said definite periods; estimating the value X of the remaining period of time which is expected to be taken before the termination of the melting operation from the following equation, X (Y-Y1)/Y1 ; and indicating at every estimation the value of X 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.