Control systems

Claim 3

The control system of claim 1 with the addition of a further control loop, operating in conjunction with said first and second control loops, for controlling the energy ratio between said first and second control loops.

Claim 4

The control system of claim 2 wherein: a. said first and second energy supplying means comprising first and second sets of electrodes, with each set including multiple first and second circuits of said electrodes; b. said first and second control loops comprising: b1. at least one first and second power supply for each of said first and second circuits, respectively; b2. first and second sensing means for sensing the amount of power applied to each of said multiple first and second circuits, respectively, with the total amount of power applied to said multiple first and second circuits, respectively, providing first and second signals proportional to the total power applied to said first and second sets of electrodes, respectively; b3. first and second controllers, having adjustable first and second set-point means, respectively, for comparing said first and second signals, respectively, with the desired power levels entered on said first and second set-point means, respectively; and b4. first and second power amplifiers through which said first and second controllers, respectively, manipulate said multiple first and second power supplies, respectively, said first power amplifier thereby driving said multiple first circuits together, to hold the total level of power applied to said first set of electrodes constant, said second power amplifier thereby driving said multiple second circuits together to hold the total level of power applied to said second set of electrodes constant, with the ratio of said first and second set-point levels defining a desired power ratio which is selected to provide the desired energy distribution for the material being melted and the melting tank being used.

Claim 5

The control system of claim 3 wherein said third control loop comprises: a. third sensing means for sensing the actual temperature within said melting tank and producing a third signal proportional to said actual temperature; b. a third controller, having an adjustable third set-point means, for comparing said third signal to the desired temperature level entered on said third set-point means; and c. adjustable first modifier means, which is also connected to said second control loop, receiving one input from said second sensing means and another input from said third controller, and having its output connected to said second controller, for modifying said second signal in a manner so that the total level of the power applied to said second set of electrodes by said second power supplies will be automatically adjusted in such a manner that the actual temperature of said bath of molten material, as measured by said third sensing means, will be held equal to the desired temperature level entered on said third set-point means, said first modifier means being adjustable, with regard to the maximum desired change of the amount of power applied to said second set of electrodes, to hold the actual temperature of said bath of molten material equal to said desired temperature.

Claim 6

The control system of claim 3 wherein said further control loop, operating in conjunction with said first and second control loops, comprises a fourth control loop for providing full authority energy ratio control between said first and second control loops, said fourth control loop comprising: a. first adjustable means for receiving said first signal; b. second adjustable means for receiving said second signal, with said first and second receiving means being adjustable so that their output signals, while being proportional to said first and second signals, respectively, are equal as long as the ratio of said first and second set-point levels remains unchanged; and c. a first signal amplifier connected to both said first and second adjustable means as well as to said first controller, said first signal amplifier serving to amplify any error signal resulting when the output signals of said first and second adjustable means become unequal due to a change in the ratio of sAid first and second point levels, said error signal thereupon driving said first power supplies (through said first controller and first power amplifier) until said error signal is reduced to zero.

Claim 7

The control system of claim 3 wherein said further control loop, operating in conjunction with said first and second control loops, comprises a fifth control loop for providing limited authority energy ratio control between said first and second control loops, said fifth control loop comprising: a. first adjustable means for receiving said first signal; b. second adjustable means for receiving said second signal, with said first and second receiving means being adjustable so that their output signals, while being proportional to said first and second signals, respectively, are equal as long as the ratio of said first and second set-point levels remains unchanged; and c. a first signal amplifier connected to both said first and second adjustable means as well as to said first controller, said first signal amplifier serving to amplify any error signal resulting when the output signals of said first and second adjustable means become unequal due to a change in the ratio of said first and second point levels; d. a fourth controller, having an adjustable fourth set-point means, and receiving as its input the amplified error signal from said first signal amplifier for comparing said error signal to a zero value entered on said fourth set-point means; and e. adjustable second modifier means, receiving one input from said fourth controller and another input in the form of said first signal and having its output connected to said first controller for modifying said first signal in a manner so that the total level of power applied to said first set of electrodes by said first power supplies (as manipulated by said first controller through said first power amplifier) will be automatically adjusted in such a manner with regard to said first set-point level as required to reach the desired power ratio, said second modifier means being adjustable with regard to the maximum change of the amount of power applied to said first set of electrodes to hold said power ratio at the desired level.

Claim 8

In combination with a first control loop for controlling both the level and distribution of the energy or power supplied to a multiple circuit first set of electrodes in a melting tank or furnace, said first control loop comprising: A. a first power supply for each circuit of said first set of electrodes; B. first sensing means for sensing the amount of power applied to each circuit, with the total amount of power applied to said multiple circuits being sensed by connecting the outputs of said sensing means in series and thereby obtaining a first signal proportional to the total power applied to said first set of electrodes; C. a first controller, having an adjustable first set-point means, for comparing said first signal to the desired power level entered on said first set-point means; and D. a first power amplifier through which said controller manipulates said power supplies, thereby driving said multiple circuits together, to hold the total level of the power applied to said first set of electrodes constant; a second control loop operating in conjunction with said first control loop, for controlling both the level and distribution of the energy or power supplied to a multiple circuit second set of electrodes in said melting tank or furnace, said second control loop comprising: a. a second power supply for each circuit of said second set of electrodes; b. second sensing means for sensing the amount of power applied to each circuit with the total amount of power applied to said multiple circuits being sensed by connecting the outputs of said sensing means in series and thereby obtaining a second signal proportional to the total power applied to said second set of electrodes; c. a second controller, having an adjustable second set-point means, for comparing said second signal to the desired power level entered on said second set-point means; and d. a second power amplifier through which said second controller manipulates said second power supplies, thereby driving said multiple circuits together, to hold the total level of the power applied to said second set of electrodes constant, with the ratio of said first and second set-point levels entered on the first and second set-point means of said first and second controllers defining a desired power ratio which is selected to provide the desired energy distribution for the material being melted and the melting tank being used.

Claim 9

In combination with a first control loop for controlling both the level and distribution of the energy or power supplied to a multiple circuit first set of electrodes in a melting tank or furnace, said first control loop comprising: A. a first power supply for each circuit of said first set of electrodes; B. first sensing means for sensing the amount of power applied to each circuit, with the total amount of power applied to said multiple circuits being sensed by connecting the outputs of said sensing means in series and thereby obtaining a first signal proportional to the total power applied to said first set of electrodes; C. a first controller, having an adjustable first set-point means, for comparing said first signal to the desired power level entered on said first set-point means; and D. a first power amplifier through which said controller manipulates said power supplies, thereby driving said multiple circuits together, to hold the total level of the power applied to said first set of electrodes constant; a second control loop operating in conjunction with said first control loop, for controlling both the level and distribution of the energy or power supplied to a multiple circuit second set of electrodes in said melting tank or furnace, said second control loop comprising: a. a second power supply for each circuit of said second set of electrodes; b. second sensing means for sensing the amount of power applied to each circuit with the total amount of power applied to said multiple circuits being sensed by connecting the outputs of said sensing means in series and thereby obtaining a second signal proportional to the total power applied to said second set of electrodes; c. a second controller, having an adjustable second set-point means, for comparing said second signal to the desired power level entered on said second set-point means; and d. a second power amplifier through which said second controller manipulates said second power supplies, thereby driving said multiple circuits together, to hold the total level of the power applied to said second set of electrodes constant, with the ratio of said first and second set-point levels entered on the first and second set-point means of said first and second controllers defining a desired power ratio which is selected to provide the desired energy distribution for the material being melted and the melting tank being used.

Claim 10

The combination as in claim 7 with the addition of a third control loop, operating in conjunction with said second control loop, for controlling the temperature within said melting tank or furnace, said third control loop comprising: a. third means for sensing the temperature within said melting tank and producing a third signal proportional to the temperature of the molten material within said melting tank; b. a third controller, having an adjustable third set-point means, for comparing said third signal to the desired temperature level entered on said third set-point means; and c. adjustable first modifier means, receiving one input from third controller and receiving another input from said second sensing means and having its output connected to said second controller, for modifying said second signal in a manner so that the total level of power applied to said second set of electrodes by said second power supplies (as manipulated by said second controller through said second power amplifier) will be automatically adjusted in such a manner that the temperature of the molten material within said melting tank, as measured by said third means for sensing, will be held equal to the desired temperature level entered on said third set-point means of said third controller, said first modifier means being adjustable, with regard to the maximum change of the amount of power applied to said second set of electrodes, to hold the temperature of the molten material equal to said desired temperature.

Claim 11

The combination as in claim 8 further including a fourth control loop, operating in conjunction with said first and second control loops, for providing full authority power ratio control between said first and second control loops, said fourth control loop comprising: a. a first adjustable means for receiving said first signal (proportional to measured total power applied to said first set of electrodes); b. a second adjustable means for receiving said second signal (proportional to measured total power applied to said second set of electrodes), with said first and second receiving means being adjustable so that the output signals, while being proportional to said first and second signals, are equal as long as the ratio of said first and second set-point values remains unchanged; and c. a first signal amplifier connected to both said first and second adjustable means and connected to the first controller of said first control loop, said first signal amplifier serving to amplify any error signal resulting when the output signals of said first and second adjustable means become unequal due to a change in the ratio of said first and second set-point values, said error signal thereupon driving said first power supplies (through said first controller and first power amplifier) until said error signal is reduced to zero

Claim 12

The combination as in claim 8 further including a fifth control loop, operating in conjunction with said first and second control loops, for providing limited authority power ratio control between said first and second control loops, said fifth control loop comprising; a. first adjustable means for receiving said first signal (proportional to measured total power applied to said first set of electrodes); b. second adjustable means for receiving said second signal (proportional to measured total power applied to said second set of electrodes); with said first and second adjustable means being adjustable so that their output signals while being proportional to said first and second signals are equal as long as the ratio of said first and second set-point values remains unchanged; c. a first signal amplifier connected to both said first and second adjustable means said first signal amplifier serving to amplify any error signal resulting when the output signals of said first and second adjustable means become unequal due to a change in the ratio of said first and second set-point values; d. a fourth controller, having an adjustable fourth set-point means, and receiving as its input the amplified error signal from said first signal amplifier, for comparing said error signal to a zero value entered on said fourth set-point means; and e. adjustable second modifier means, receiving one input form said fourth controller and another input in the form of said first signal and having its output connected to said first controller of said first control loop, for modifying said first signal in a manner so that the total level of power applied to said first set of electrodes by said first power supplies (as manipulated by said first controller through said first power amplifier) will be automatically adjusted in such a manner with regard to said first set-point value as required to reach the desired power ratio, said second modifier means being adjustable with regard to the maximum change of the amount of power applied to the said first set of electrodes to hold said power ratio at the the desired level.