US1449883A - Furnace-regulator system - Google Patents

Description

Mar. 27, 1923. 1,449,883.

0. A. BODDlE. FURNACE REGULATOR SYSTEM.

FILED AUG.26 1919.

WITNESSES: INVENTOR BY M ATTORNEY Patented Mar. 27, 1923.

UNITED STATES PATENT OFFICE.

CLARENCE A. BODDIE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

Application filed August 26, 1919.

To all whom it may concern:

Be it known that I, CLARENCE A. BODDIE, a citizen of the United States, and a resident of Pittsburgh, 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 1 and particularly to regulator systems for governing the operation of the movable electrodes in electric furnaces.

One object of my invention is to provide a furnace-regulator system that shall be governed in accordance with the current and the voltage conditions of the furnace and that shall be substantially free from so-called hunting action.

Ky, Heretofore, it has been customary to control each movable electrode of an electric furnace by a main magnet which was energized in accordance with the current flowing through it and to vary the energization ofthe winding of said magnet to prevent hunting action. The above operation of a furnace electrode is fairly satisfactory under normal operating conditions, but, at times, trouble is encountered if no account is taken of the voltage across the electrode arc. Thus, in a three-phase electric furnace, the resistance of the material being treated may vary in different parts of the furnaceand, consequently, the various'electrode circuits may have difi'erent resistance values. In such case, the current flowing through the various electrodes will be varied in a manner to produce different arcs by the difl'erent electrodes and, consequently, to produce difl'erent heating efiects in the furnace. It has been proposed to control the main magnet of the furnace-regulating system not only 'in accordance with the current flowing through'the electrode but also in accordance with the potential across the electrode arc. 45 However, in such regulating systems, it is customary to shunt the current winding by means of an adjusting resistor for governing the, energization of thecurrent winding but such adjusting resistor causzs a considerable lag inthe current flowing through the FURNACE-REGULATOR SYSTEM.

Serial No. 319,903.

current winding and, consequently, the currents flowing through the current winding and the potential winding will not co-act to jointly control the operation of the electrode.

In a furnace-regulator system constructed in accordance with my invention, each movable electrode is provided with a motor which is controlled by a main magnet not only in accordance with the current flowing through the electrode but also in accordance with the oltage obtaining across the electrode arc. The main magnet comprises a winding which is energized in accordance with the current flowing through the electrode and a 05 second winding which is energized in accordance with the potential obtaining across the electrode arc. The current winding is shunted by means of an adjusting resistor which produces a very low power factor in the current winding and, consequently, some means must, be provided for adjusting the currents flowing through the potentia and the current windings to the same phase relation. In order to accomplish such ob- 15 ject, an inductor is connected in series with the resistor which shunts the current winding for increasing the power factor of that winding and a second inductor is connected in circuit with the potential winding for lowering the power factor of such windrng.

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

Referring to the drawing, an electric furnace 1, compris'ng a receptacle 2 containing a bath of material 3 and three movable electrodes 4,, 5 and 6, is directly connected to a three-phase supply circuit comprising conductors 7, Sand 9. x

Each of the electrodes 4,. 5 and 6 is provided with an electrode motor and a regulator for adjusting the electrode in accordance with the voltage and the current conditions of the electrode circuit and, inasmuch as the associated motors and regulators are similar, in construction and operation, it is deemed suflicient to illustrate and describe the construction and operation of but one 1 0 ated with the electrode 6.

A motor 10, comprising an armature -11 and a field winding 12, is provided for raising and lowering the electrode 6 and is mechanically connected to the electrode in any suitable manner, as by means of a winding reel 13 and a flexible connector 14 which passes over a pulley 15. The field winding 12 is directly connected to an auxiliary supply circuit comprising conductors 16 and 17.

A main magnet 18, which is operated in accordance with the current and the voltage conditions of the circuit of the electrode 6, is provided for selectively operating two switches 19 and 20 and for connecting the armature 11 across the supply conductors 16 and 17 to rotate the motor 10 in a clockwise and in a counter-clockwise direction. The main magnet 18 comprises a current winding 21 which is connected to the threephase supply conductor 9 by means of a current transformer 22 and a potential winding 23 which is connected across the arc produced by the electrode 6. The two windings 21 and 23 operate a core armature 24 which is provided with a dash-pot 25 for adjusting its operation and is pivotally connected to a contact arm 26. The contact arm 26 is fulcrumed at 27 and-is provided with a main contact member 28 which engages contact members 29 and 30 according to the operative position of the main magnet 18.

The switch 19 comprises a winding 31, which is connected across the supply conductors 16 and 17 upon engagement between the contact members 28 and 30, and a core armature 32 which operates two switch members 33 and 34 and two interlock switch members 35 and 36. The two switch members 33 and 34 serve to connect the armature 11 across the supply conductors 16 and 17 for operating the motor 10 in a counterclockwise direction to raise the electrode 6 and, consequently, to decrease the current flowing through said electrode. The interlock switch member 36 serves, upon operation of the switch 19, to complete a shortcircuit across that portion of the current winding 21 which is included between taps 37 and 38 for preventing any hunting action.

The switch 20 comprises a winding 39, which is connected across the supply conductors 16 and 17 upon engagement between the contact members 28 and 29, and a core armature 40 which operates two switches 41 and 42 and two interlocking- switch members 43 and 44. The switch members 41 and42 connect the armature 11 across the supply conductors 16 and 17 for rotating the motor 10 in a clockwise direction to lower the electrode 6 and, consequently, to increase the current flow through -it. The interlock switch member 44, upon operation of the switch 20, serves to open a short-circuit which normally obtains across that portion of the winding 21 which is included between taps 37 and 45 for preventing any hunting action when the electrode 6 is being lowered in the furnace. The interlock switch members 35 and 43, upon release of the two switches 19 and 20, complete an energizing circuit for a brake relay 46 from the supply conductors 16 and 17. The relay 46, upon operation, completes a dynamic-braking circuit through a resistor 47 for the armature 11 of the motor 10.

In order to adjust the current flow through the current winding 21 of the main magnet 18, it is necessary to shunt the winding by means of an adjustable resistor 50 and, inasmuch as such connection increases the lag of the current flowing through the Winding 21, it is necessary to either decrease the lag of the current flowing through the winding 21 or to'increase the lag of the current flowing through the winding 23 in order to obtain joint action on the core armature 24 by the two windings. Accordingly, a resistor 51 is connected in series with the winding 21, and an inductor 52 is connected in series with the resistor 50 for decreasing the lag of the current flowing through the winding 21 and, moreover, a res stor 53 and an inductor 54 are connected in series with the winding 23 in order to increase the lag of the current flowing through the winding-23. Accordingly, the-lag in the current flowing through the winding 21 is reduced and the lag of the current flowing through the winding 23 is increased to bring the currents flowing through the two coils to the same phase relation.

In case a current above normal value flows through the electrode 6 or the potential across the are produced by the electrode 6 is below normal value, the main magnet 18 is operated to effect engagement between the contact members 28 and 30. Thereupon, a circuit is completed from the supply conductors 16 and 17 for operating the switch 19. The motor 10 is rotated in a counter-clockwise direction for raising the electrode 6 to decrease the current flow ing through it and to raise the potential across the are produced .by it.

If no anti-hunting means were provided.

. order to change the settin tact members 28 and just prior to the obtaining of .normal electrode-circuit conditions.

In case the current flow through the electrode 6 is below normal value and the potential across the electrode 6 is above normal value, the main magnet 18 is operated to effect engagement between the contact members 28 and 29 for operating the switch 20. Upon operation of the switch 20, the motor 10 is rotated in a clock-wise direction for lowering the electrode 6 to increase the current flow'through it and to decrease the potential across the electrode arc. Simultaneously with the operation of the motor 10, the interlock switch member 44 opens the short-circuit which normally obtains across that portion of the winding 21 which is included between the taps 37 and 45 for changing the-setting of the main magnet i 18. Thus, the magnet 18 is operated to effect separation of the contact members 28 and 29 just prior to the obtaining of normal electrode-circuit conditions for preventany hunting-action.

in In the system above described, it will be noted that a main magnet is provided with a current and a potentlal windin for governlng the operation of the associated electrode, not only in accordance with the current conditions of the furnace but also in accordance with the potential obtaining across the electrode ar Moreover, means is provided for preventing an hunting action on the part of'gthe regu ator and for maintaining the currents in the potential and the current winding of the main magnet in the same base relation.

Modifications 1n the system and arrangement and ocation of parts may be made within the spirit and scope of my invention,

and such modifications are intended to be covered by the appended claims.

I claim as my invention: '1. In a furnace-regulator system; the

combination with a movable electrode, and

a motor for'raising and lowering said elec-. trade, of means comprising an electro-magnet for controlling said motor to maintain the electrode are constant, said electromagnet having a winding energized in accordance with the current flowing through the electrode and a windin combination with a movable electrode, and

means comprising an electro-magnet having a current and a potential winding for energized in accordance with the potential across the governing said electrode to maintain a constant electrode arc, of means for maintaining the currents In said windings in the same phase relation.

3. In a. furnace-regulator system, the combination comprising a movable electrode,-a 'magn'et having a winding connected in series with the electrode and a second winding connected across the electrode arc, and resistors and inductors connected .in various relations to said windings for adjusting the energization of the magnet and for regulating the phase relation of the currents in the windings.

4. In a furnace-regulator system, the combination comprising a movable electrode, means comprising a magnet having a current and a potential winding for maintaining a constant electrode arc, and means for varying the number of active turns of one of said windings to prevent any hunting action.

5. In a furnace-regulator system, the combination with a movable electrode, and a motor for raising and lowering said electrode, of a magnet having a windin energized in accordance with the current owing through the electrode and a winding energized inaccordance with the potential obtaining across the electrode are for controlling said. motor to maintain a constant electrode arc, and means comprising resistors and inductors for varying the impedance of the circuits of said windings to maintain the bination with a movable electrode, and means comprising a'niagnet having a current and a potential winding for maintaining a constant electrode arc, of means for varying the number of active turns of one of said windings to prevent hunting action, and means inserted in the circuits of said windings for regulating the phase relation of the currents flowing through the windings.

8. a-regulator system, the combination with a movable electrode and a motor for raising and lowering said electrode, of a regulator for governing theoperation of said motor to maintain a constant electrode arc, Said regulator comprising an electromagnet having a winding energized in accordance with the current'flowing through circuit and means for varying-the energiza 15 Eion of the current winding to prevent huntng action. 1

10. In a furnace-regulator system, the combination comprising a movable electrode, means comprising a regulator for governing the operation of said electrode to maintain a constant electrode are, said regulator comprising one electi'omagnet having a current i and a potential Winding energized from the electrode circuit, and means for varying the energization of one of said windings to prevent hunting action.

11. In a furnace-regulator system, the combination with a movable electrode and a plural-coil electromagnet energized in accordance with electrode circuit conditions to maintain a constant electrode arc, of means for maintaining predetermined phase rela tions of the currents traversing said coils.

12. In a furnace-regulator system, the combination comprising a movable electrode, means comprising a plural-coil electromagnet energized in.accordance with electrode circuit conditions to maintain a constant electrode arc and means for varying the effect of one of said coils to prevent hunting action.

In testimony whereof, I have hereunto subscribed my name this 12th day of Aug, 1919.

CLARENCE'A'. BODDIE.

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