US4620308A — Arc furnace electrode control

Claim 1

Independent Claim 199 words

A control for positioning the electrodes of a poly-phase electric arc furnace energized by a poly-phase transformer having primary and secondary windings, and including control means for individually elevating and lowering each of the electrodes, the improvement comprising: a plurality of first circuit means each coupled respectively to one of the primary phases of the transformer and each being operable respectively to generate a first electrical output signals functionally related to the phase angles between the voltage and current in each phase of the transformer primary, bias circuit means coupled to each of the phases of the transformer primary for producing an additional output signal functionally related to the reactive volt amperes delivered to the transformer primary, comparison means coupled to said first circuit means and said bias circuit means for respectively comparing the additional signal and each of said first signals to a preselected value and for producing a plurality of control signals related to differences in said signals, said control means coupled to said comparison means and being responsive to said control signals for selectively positioning each electrode whereby each electrode will be positioned in accordance with deviations in the phase angle in its respective primary circuit.

Claim 2

Dependent Claim 199 words

A control for positioning the electrodes of a poly-phase electric arc furnace energized by a poly-phase transformer having primary and secondary windings, and including control means for individually elevating and lowering each of the electrodes, the improvement comprising: a plurality of first circuit means each coupled respectively to one of the primary phases of the transformer and each being operable respectively to generate a first electrical output signals functionally related to the phase angles between the voltage and current in each phase of the transformer primary, bias circuit means coupled to each of the phases of the transformer primary for producing an additional output signal functionally related to the reactive volt amperes delivered to the transformer primary, comparison means coupled to said first circuit means and said bias circuit means for respectively comparing the additional signal and each of said first signals to a preselected value and for producing a plurality of control signals related to differences in said signals, said control means coupled to said comparison means and being responsive to said control signals for selectively positioning each electrode whereby each electrode will be positioned in accordance with deviations in the phase angle in its respective primary circuit.

Claim 3

Dependent Claim 46 words

The control set forth in claim 1 wherein each of said plurality of first circuit means comprises a phase angle measuring circuit, coupled respectively to one phase of the primary of said transformer for sensing the zero point of the voltage and current in each phase.

Claim 4

Dependent Claim 60 words

The control set forth in claim 2 wherein said bias circuit means comprises a reactive volt ampere measuring circuit coupled to each of the primary phases for receiving an electric signal functionally related to the magnitude of the voltage and current therein for generating an output electrical signal functionally related to the reactive volt ampere consumption in said primary circuit.

Claim 5

Dependent Claim 58 words

The control set forth in claim 3 wherein said comparison means comprises a plurality of null detection means coupled respectively to receive one of said plurality of first electrical output signals and said additional output signal and each being operative for producing control signals functionally related to the difference between said output signals and a set point signal.

Claim 6

Independent Claim 157 words

A method for individually controlling the position of electrodes in a polyphase electric arc furnace wherein said electrodes are energized by a polyphase transformer having primary and secondary windings wherein each secondary winding is connected to one of the electrodes for providing phase voltage and current thereto, separately measuring the phase angle between the voltage and current in each primary phase conductor connected to the transformer primary windings, generating angle electrical signals functionally related to the phase angle in each of the primary conductors, measuring the reactive load at the primary transformer windings and generating a bias electrical signal functionally related thereto, separately comparing each of said phase angle signals and the bias signal to a preset quantity and generating separate control signals based on each such comparison, and individually positioning each of the electrodes in relation to a charge in the arc furnace in relation to the magnitude and the sense of the respective control signals.

Claim 7

Independent Claim 157 words

A method for individually controlling the position of electrodes in a polyphase electric arc furnace wherein said electrodes are energized by a polyphase transformer having primary and secondary windings wherein each secondary winding is connected to one of the electrodes for providing phase voltage and current thereto, separately measuring the phase angle between the voltage and current in each primary phase conductor connected to the transformer primary windings, generating angle electrical signals functionally related to the phase angle in each of the primary conductors, measuring the reactive load at the primary transformer windings and generating a bias electrical signal functionally related thereto, separately comparing each of said phase angle signals and the bias signal to a preset quantity and generating separate control signals based on each such comparison, and individually positioning each of the electrodes in relation to a charge in the arc furnace in relation to the magnitude and the sense of the respective control signals.

Claim 8

Dependent Claim 186 words

A control for individually positioning the electrodes of an electric arc furnace energized by a multi phase power source, and including control means for individually elevating and lowering each of the electrodes, the improvement comprising: a plurality first circuit means coupled respectively to one of the phases of the power source and being operable respectively to generate separate electrical output signals functionally related to the phase angles between the voltage and current in each of said phases, bias circuit means coupled to each of the phases of the power source for producing an electrical bias signal functionally related to the reactive volt ampere loads of the electrodes, comparison means coupled to the first circuit means and the bias circuit means respectively comparing the bias signal and each of said output signals to a preselected value and for producing individual signals related to differences in said signals, said control means coupled to the comparison means and being responsive to said control signals for selectively positioning each electrode whereby each electrode will be positioned in accordance with deviations in the phase angles in its respective phase power supply.

Claim 9

Dependent Claim 186 words

A control for individually positioning the electrodes of an electric arc furnace energized by a multi phase power source, and including control means for individually elevating and lowering each of the electrodes, the improvement comprising: a plurality first circuit means coupled respectively to one of the phases of the power source and being operable respectively to generate separate electrical output signals functionally related to the phase angles between the voltage and current in each of said phases, bias circuit means coupled to each of the phases of the power source for producing an electrical bias signal functionally related to the reactive volt ampere loads of the electrodes, comparison means coupled to the first circuit means and the bias circuit means respectively comparing the bias signal and each of said output signals to a preselected value and for producing individual signals related to differences in said signals, said control means coupled to the comparison means and being responsive to said control signals for selectively positioning each electrode whereby each electrode will be positioned in accordance with deviations in the phase angles in its respective phase power supply.

Claim 10

Dependent Claim 174 words

A control for positioning the electrode of an electric arc furnace energized by a transformer having primary and secondary windings, and including control means for individually elevating and lowering the electrode, the improvement comprising: first circuit means coupled to the primary of the transformer and being operable to generate a first electrical output signal functionally related to the phase angle between the voltage and current in the transformer primary, bias circuit means coupled to the transformer primary for producing a second output signal functionally related to the reactive volt amperes delivered to the transformer primary, comparison means coupled to said first circuit means and said bias circuit means for comparing the first and second signals to a preselected value and for producing a control signal related to differences between said signals and said preselected value, said control means coupled to said comparison means and being responsive to said control signals for selectively positioning each electrode whereby each electrode will be positioned in accordance with deviations in the phase angle in its respective primary circuit.

Claim 11

Dependent Claim 174 words

A control for positioning the electrode of an electric arc furnace energized by a transformer having primary and secondary windings, and including control means for individually elevating and lowering the electrode, the improvement comprising: first circuit means coupled to the primary of the transformer and being operable to generate a first electrical output signal functionally related to the phase angle between the voltage and current in the transformer primary, bias circuit means coupled to the transformer primary for producing a second output signal functionally related to the reactive volt amperes delivered to the transformer primary, comparison means coupled to said first circuit means and said bias circuit means for comparing the first and second signals to a preselected value and for producing a control signal related to differences between said signals and said preselected value, said control means coupled to said comparison means and being responsive to said control signals for selectively positioning each electrode whereby each electrode will be positioned in accordance with deviations in the phase angle in its respective primary circuit.

Claim 12

Dependent Claim 34 words

The control set forth in claim 7 wherein said first circuit means comprises a phase angle measuring circuit means coupled to transformer primary for sensing the zero point of the voltage and current therein.

Claim 13

Dependent Claim 58 words

The control set forth in claim 8 wherein said bias circuit comprises a reactive volt ampere measuring circuit coupled to the transformer primary for receiving an electric signal functionally related to the magnitude of the voltage and current therein for generating an output electrical signal functionally related to the power reactive volt ampere consumption in said primary circuit.

Claim 14

Dependent Claim 47 words

The control set forth in claim 9 wherein said comparison means comprises a null detection means coupled to receive the first and second output signals and being operative for producing a control signal functionally related to the difference between said output signals and a set point signal.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1989-10-27	1990-04-28	1990-10-28	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1993-10-27	1994-04-28	1994-10-28	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1997-10-27	1998-04-28	1998-10-28	$7700.00	Window Closed / Lapsed

Arc furnace electrode control

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag