US1449593A - Furnace-regulator system - Google Patents

Description

Patented Mar. 27,1923.

UNITED STATES PATENT OFFICE.

ROBERT D. EVANS, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

FURNACE-REGULATOR SYSTEM.

Application filed ,0ctober 30, 1918. Serial No. 260,277.

To'aZZ whom it may concern:

Be it known that 1, ROBERT D. EVANS, a citizen of the-United States, and a resident of Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Furnace- Regulator Systems, of which the following is a specification.

My invention relates to regulator systems and particularly to regulator systems for governing the operation of electric furnaces.

One object of my invention is to provide a regulator system of the above-indicated character that shall control the operation of a furnace in an eflicient manner and be substantially free from hunting action.

Another object of my invention is to provide .a regulator system for an electric furnace, having motor-operated electrodes, that shall govern the operation of the motors for raising and for lowering the electrodes in accordance with the current supplied to the furnace and be provided with means for preventing hunting action thereby which isgoverned in accordance with the operation of the motors.

In electric furnaces, it is very desirable that the movable electrodes be automatically raised and lowered by motors, preferably electric motors, in accordance with the current supplied to the furnace or by the arcs formed .by the respective electrodes. Moreover, it is customary to provide electric furnaces of the above character with regulator systems for governing the operation of the motors which control the movements of the electrodes, and the regulator systems-are usually provided with anti-hunting devices for stabilizing the operation of the furnaces.

In an electric-furnace-regulator ,system' constructed according to my invention, a motor is provided for raising and lowering each movable electrode of th'e'furnace in aca prises two electromagnets which oppose each other, one of the electrom'a ets being cordance with the current flowing through such electrode. Eachregu'lator mm coine'nergized in accordance with-'t 'e current flowing through the electrode associated; with thel regulator for governing :the'operationof two; switches which" controith'e op;

through the motor whenever the regulator,

is in a normal position.

The single figure of the accompanying drawing is a diagrammatic view of a furnace-regulator system embodying my invention."

Referring to the drawing, an electric furnace 1, embodying two movable electrodes 2 and 3, and a receptacle 4, containing abath of material 5, is c'onnectedto a threephase supply circuit comprising conductors 6, 7 and 8. The'supply conductors 7 and 8 are respectively connected to the electrodes 2 and 3, and the supply conductor 6 is connected to the bath of material 5.

Two motors 9 and 10, respectively com prising armatures 11 and 12, and field windings 13 and 14, are provided for raising and lowering the electrodes 2 and 3 by any suitable means, such, for example, as drums 15 and 16, which are mounted upon the shafts of the armatures l1 and 12, and flexible connecting means 17 and 18 which are connected to the electrodes 2 and 3 and are adapted to be wound upon the drums 15 and 16.

The motor 10, which governs the operation of the electrode 3, is controlled by means of a regulator 20, in accordance with the current supplied to the electrode 3, a'nd the motor 9, which operates the, electrode 2, is governed by a regulator'2l,'in accordance with the current that is supplied to. the furnace throughthe electrode 2 {The regulae tor 20. embodies amain control electromagneti22 havi'ng a=winding.23, which is connected-to the supplyconductorB by means of=a current transformer 24:, an adjustable resistorj25 being connected across the windating' the speed of operation of :the' main control gelectromagnet 22. The;

in 23 for regu main. control -electromagnet. 22.; further em-i bodies a core member 26 which is pivotally connected to a contact arm 27 and is maintained in a retracted position by means of a spring 28. The contact arm 27 is provided with a contact member 30 which is selectively moved into engagement with contact fingers 31 and 32, according to the energization of the main control electromagnet 22. An auxiliary polarized magnet 33, having a winding 34 and a core 35, is connected to the contact arm 27 and is adapted to oppose the action of the main control magnet 22, under predetermined condltions, for preventino a hunting action by the regulator. The winding 34 of the auxiliary electromagnet is connected across the armature 12 of the motor 10 and is shunted by means of an adjustable resistor 36 for adjusting the speed of its operation.

Two electromagnetic switches 37: and 38, which are selectively operated by means of the main control magnet 22, are provided for determining the direction of rotation of the motor 10 and, consequently, the position of the electrode 3 relative to the bath of material 5. The switch 38 embodies a winding 39, which is connected across an auxiliary supply circuit,comprising conductors 40 and 41, whenever the contact members 30 and 31 are in engagement with each other, and three switch members 42, 43 and 44. The two switch members 42 and 43 serve for connecting the armature 12 of the motor 10 through a resistor 45, across the supply conductors 40 and 41, in order to effect rotation of the motor 10 in a counter-clockwise direction and thus raise the electrode 3.

The switch 37 embodies a winding 46, which is connected across the supply conductors 40 and 41 when the contact terminals 30 and 32 are in engagement with each other, and three switch members 47, 48 and 49. The two switch members 47 and 48 serve for connecting the armature 12 of the motor 10 across the supply conductors 40 or 41 in a manner to effect rotation of the motor 10 in a clockwise direction and thus permit the lowering of the electrode 3. The switch members 49 and 44 of the switches 37 and 38 serve for completing a dynamic braking circuitthrough the armature 12 whenever the two switches are in released positions. The field winding 14 of the motor 10 is connected across the supply conductors 40 and 41, through an adjustable resistor 50.

The regulator 21, which governs the operation of the motor 9 in accordance with the current supplied to the electrode 2, em-

4 bodies a mam-control or contact-making ammeter 52 having an energizing winding 53 and a core member 54, which is pivotally connected to a contact arm 55. The core member 54is retracted by means of a spring 56.- and the energizing winding 53 is connected tothe supply conductor 7 by means of a current transformer 57. An adjustable resistor 58 is provided for governing the sensitiveness of the magnet. The contact arm 55 is provided with a contact terminal 60 which selectively engages the contact fingers 61 and 62 according to the energization of the magnet 52. L

An auxiliary polarized magnet 63, comprising a winding 64 and a core member 65, which is pivotally connected to the contact arm is provided for opposing the action of the electromagnet 52 under predetermined conditions so as to prevent a hunting action by the regulator 21. The winding 64 is connected directly across the armature 11 of the motor 9 in order to be energized in accordance with the counter-electromotive force (of the motor, and an adjustable resistor 66 is connected across the winding 64 for gover ing the sensitiveness of the auxiliary magnet.

Two switches 69 and 70 are selectively controlled by the main-control electromagnet 52 for governing the direction of rotation of the motor 9 and,accordingly, the position of the electrode 2. The switch 70 embodies a winding 71, which is connected across the supply conductors 40 and 41 whenever the contact members 60 and 61 are in engagement with each other, and three contact members 72, 73 and 74. The two contact members 72 and 73 serve to connect the armature 11 through a resistor 75 across the I supply conductors 40 and 41 whenever the switch 70 is in an operative position. The motor 9 is rotated in a counter-clockwise direction when connected to the supply con-V ductors 40 and 41, through the switch members 7 2 and 7 3. in order to raise the electrode 2 from the bath of material 5. r

The switch 69 embodies a winding 76, which is connected across the supply conductors 40 and 41 when the contact members 60 and 62 are -in engagement with each other, and three switch members 77, 78 and 79. The two switch members 77 and 78 serve for connecting the armature 11 of the motor 9 across the supply conductors 40 and 41 in a manner to effect clockwise rotation of the motor and thus permit a lowering of the electrode 2. The switch members 79 and 74 of the switches 69 and 70 serve for completing a dynamic-braking circuit through the armature 11 whenever the switches are in a released position. The field winding 13 of the motor 9 is connected across the supply conductors 40 and 41, through an adjustable resistor 80.

In order to explain the operation of the thebath of material 5 that the current flowing through the conductor 8 is above normal value, the energization of the winding 23 of the contact-making ammeter 22 will beincreased in a manner to effect engagement between the 'contact members 31 and 30.

' Upon engagement of thecontact members 30 when the counter-electromotive force of the armature 12 is raised to a predetermined point, the auxiliary magnet 33 will overcome the action of the contact-making ammeter 22 and de-energize the motor 10 by releasing the switch 38. In this regard, it may be noted that the time at which the auxiliary electromagnet 33 overcomes the action of the magnet 22 may be adjusted by means of the resistors 25 and 36 which are respectively associated with the windings 23 and 34 of the two electromagnets. The auxiliary magnet is adapted to stop the motor 10 at such point as to prevent over travel thereby and consequent hunting by the regulator 20.

In case the electrode 3 is raised above the bath of material 5 to such position that a current below normal value is flowing through the supply conductor 8, the energization of the contact-making ammeter 22 is reduced to such point that engagement is effected between the contact members 30 and Upon engagement of the contact members 30 and 32, the switch 37; is operated for connecting the armature 12 of the motor 10 across the supply conductors 40 and 41. Thus the motor is operated in a clockwise permit the lowering of the electrode 3. Simultaneously with the operation of the motor 10, the polarized auxiliary magnet 33 is energized by the counter-ele'ctromotive force of the armature 12 to separate the contact members 30 and 32.

It is deemed inadvisable to completely I trace the operation of the regulator 21 for governing the motor 9 to determine the'position of the electrode 2, inasmuch as the regulator 21 operates in a manner-similar to the operation above set forth in'discussing the regulator 20. From the above description, it will be notedthat the two electrodes 2 and 3 are governed in accordance with the current which is supplied to them 1 through the conductors 7 and. 8 and that a hunting action is prevented by the auxiliary polarized magnets 33 and 63, which-are governed in accordance with the counter: electromotive' force of the motors?) andv l0.

. regulator.

netic device having two electromagnets for,

controlling the operation of the motor, one of said electromagnets "being energized in accordance with the current supplied to the furnace and the second'electromagnet being energized in accordance with the electrical conditions of the motor to prevent hunting .action by said device.

2. In combination, an electric furnace, a

motor for adjustingan electrode of the furnace, a regulator comprising means for operating' the motor in accordance with the current supplied to the furnace and for completing a dynamic. braking circuit through the motor, and means controlled by the counter-electromotive force of the motor for preventing hunting action by the 3. In combination, an electric furnace having an operating motor, and a regulator comprising a main electromagnet for operating the motor in accordance with the current supplied to the furnace and means comprising an uxiliary electromagnet governed in accordance with the motor electrical conditions for opposing the action of the main electromagnet to prevent hunting action b it.

4. he combination with a supply circuit, and an electric furnace connected to the supply circuit, of a motor for adjusting the furnace, an electromagnetoperated in accordance with the current supplied to the furnace, two switches selectively operated by said electromagnet for governing the operation of the motor, and means controlled by the motor for preventing hunting action by'the electromagnet.

5. The combination with a supply circuit,-an electric furnace connected to the supply circuit, and a motor for varying the are obtained in the furnace, of an electro- '6. .The combination with a supply circuit I and an electric furnace connected to the supply circuit, of a motor for raising and owering a furnace electrode, an electric regulator-comprising a main electromagnet for selectively effecting rotation of the motor in-accordancewith the current supplied to the furnace, and means comprisingan I auxiliary magnet controlled by said motor I of said regulator to prevent hunting action.

8. Thecombination with a polyphase supply circuit, and an electric furnace connected to the supply circuit, of motors for operating the furnace electrodes, and regulators for severally operating said motors in accordance with the current supplied to the furnace, and means controlled by the counter-electromotive force of the motors for modifying the action of said regulators to prevent hunting action.

9. The combination with an electric fur- 'nace having a plurality of electrodes, and a polyphase supply circuit connected to the furnace, of,mo,tors for varying the position of the electrodes, regulator means for selectively operating the motors in a forward and in a reverse direction according to the current supplied to the furnace and for completing dynamic braking circuits through the motor, and means governed by the counter-electromotive force of the motors for preventing hunting action by the regulator means.

- 10. In a regulator for an electric furnace having an electric motor for adjusting the arc formed therein, an electromagnet operated in accordance with the current supplied to the furnace, two'switches controlled by said electromagnet for operating the motor in a forward and in a reverse direction and for completing a dynamic-braking cir- 1n I cult through the motor under certain conditions, and means controlled by the motor for preventing hunting action by said electromagnet.

11. In a regulator for an electric furnace having an electric motor for adjusting the are formed therein, electromagnetic means operated in accordance with the current supplied to the furnace, two switches selectively operated by said means for effecting operation of the motoreither in a forward or in a reverse direction, an electromagnet for opposing the action of said electromagnetic means, and means for energizing said electromagnet in accordance with the counterelectromagnetic force of the motor to prevent hunting action by the electromagnetic means.

12. In a regulator for an electric furnace, the combination comprising an electric motor and a main control element for governbraking circuit thr ugh the motor, and means for modifying the operatlon of the regulator in accordance with the electric conditions of the associated motor to prevent hunting action.

14. In combination, a plurality of energytranslating devices, means for severally adjusting said devices in accordance with the amount of current being supplied thereto, and means controlled by an electrical condition of said adjusting means for changing the action of said adjusting means to prevent hunting action.

15. The combination with a supply circuit and a plurality of energy-translating devices connected thereto, of regulators comprising means for severally adjusting said devices in accordance with the current traversing said devices and means controlled by an electrical condition of said adjusting means for changing the action of said adiusting means to prevent hunting action.

16. The combination with a supply circuit and a plurality of energy-translating devices connected thereto, of means for adjusting said devices, regulating means for controlling said adjusting means in accordance with the amount of current being supplied to said devices and means controlled by an electrical conditionwof said adjusting means for changing the action of said regulating means to anticipateand prevent hunt- 17. In combination, a supply circuit, a. plurality of energy-translating devices connected thereto, means for severally adjusting said devices to maintain a predetermined value of current translated, regulatingmeans for said adjusting means, and means effective during the operation of said adjusting means for changing the action of said regulating means in proportion to the variation from said predetermined value.

18. In combination, a supply circuit, a plurality'of energy-translating devices connected thereto, means for severally adjusting said devices to maintain a predetermined value of current translated, regulating means for said adjusting means, and means for causing said regulating means to demergize said adjusting means before said predetermined value of energy is reached, the difference between the value at which said adjusting means is de-energized and said termined value of current through said furnace and meansfor causing said regulator to de-energize said motor before sald predetermlned value is reached, the difference in value at which said motor is de-energized and said predetermined value being proportional to the counter electromotive force of said motor.

20. The combination with a supply circuit and an electric furnace connected thereto, of a motor for raising and lowering a furnace electrode, an electric regulator comprising a main electromagnet for selectively effecting rotation of the motor to maintain a predetermined value of current traversing said electrode and means comprising an auxiliary ma et controlled by said motor for so modifying the action of the main magnet as to cause it to effect de-energization of said motor before'said predetermined value of current through said electrode is reached.

21. The combination with a supply circuit and an electric furnace connected thereto, of a motor for raising and lowering a furnace electrode, an electric regulator comprising a main electromagnet for selectively effecting rotation of the motor to maintain a predetermined value of current'traversing said electrode, and means comprising an auxiliary magnet controlled by said motor for so modifying the action of the main magnet as to cause it to effect de-energization of said motor before said predetermined value of current through said electrode is reached, the difference between the current value at which said motor is de-energized and said predetermined current value being directly in proportion to an electrical condition of said motor.

22. The combination with a supply circuit and an electric furnace connected thereto, of a motor for raising and lowering a furnace electrode, an electric regulator comprising a main electromagnet for selectively effecting rotation of the motor to maintain a predetermined value of current traversing said electrode, and means comprising an auxiliary magnet controlled by said motor for so modifying the action of the .main magnet as to cause it to effect de-energization of said motor before said predetermined value of current through said electrode is reached, the diiference between the current value at which said motor is de-energized and said predetermined current val- :ie being directly in proportion to the counter electromotive force of said motor.

In testimony whereof, I have hereunto subscribed my name-this 18th day of Oct. 1918.

ROBERT D. EVANS.

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