US1449888A - Furnace-regulator system - Google Patents

Description

Mar. 27, 1928. 1,449,888. S c, A. BODDIE.

FURNACE REGULATOR SYSTEM.

FILED DEC. 3, I919- WITNESSES: INVENTOR Patented Mar. 27, 1923.

; UNITED STATES PATENT OFFICE.

CLARENCE A. BODDIE, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENN SYLVANIA.

FURNACE-REGULATOR SYSTEM.

Application filed December 3, 1919. Serial No. 342,174.

To all whom it may concern:

Be it known that I, CLARENCE A. Bonnm, 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- Regulating Systems, of which the following is a specification.

My invention relates to regulator systems 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 have a main magnet for govermn the operation of each movable electrode 1n accordance with the current flowing through it and that shall be provided with two differentially-wound coils which co-operate with the main magnet and are selectively connected across the electrode arc to prevent hunting action.

At the present time, it is customary .to govern the movements, of the movable electrodes in accordance with the current flowing through them. However, such regulation is impractical in some respects unless some means is provided for preventing so called hunting action.

In practicing my invention, each movable electrode is operated in accordance with the current flowing through it, and means, comprising two difl'erential windings, are selectively energized to so change the setting of the main magnet as to prevent hunting action. In the preferred form of practicing my invention, each electrode'is raised and lowered by means of an electrode motor and the motor is selectively operated in a clockwise and in a counterclockwise direction by means of two switches. A main magnet, having three windings, is provided for selectively operating the two switches in accordance with the current flowing through the electrode. One of said magnet windings is so connected to the electrode circuit as to be operated in accordance with the current flowing through the electrode. Two 'of the magnet windings are differentially wound and are selectively connected across the electrode are by the two switches in order to change the setting of the magnet and prevent so-c-alled hunting action. Means are also pr vided for completing a dynamic-braking circuit through the electrode-motor armature upon the simultaneous release of the two switches.

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

Referring to the drawing, an electric furnace 1, comprising three movable electrodes 2, 3 and 4 and a receptacle 5, containing a bath of material 6, is connected to a threephase supply circuit comprising conductors 7, 8 and 9. Y

Each of the movable electrodes 2, 3 and 4 is raised and lowered by means of a separate electrode motor, and a regulator is associated with each electrode motor in order to operate the motor in accordance with the current flowing through the electrode connected to it. Inasmuch as the electrode motors and 'the regulators associated with them are similar in construction and operation, it is deemed sufficient to describe the construction and operation of but one electrode motor and one regulator, namely, the

A motor 10, comprising an armature 11 'and a field-magnet winding 12, is provided for raising and lowering the electrode 4.

The field-magnet winding 12 is directly connected across an auxiliary supply circuit comprising conductors l3 and 14, and the armature is selectively connected across the supply conductors 13 and 14 by means of two switches 15 and 16 in order to govern the direction of the rotation of the motor 10 and, accordingly, the position of the electrode 4. The armature 11 is mechanically connected to the electrode 4 in any suitable manner, as by means of a winding reel 17 and a flexible connector 18 which passes over a pulley 19.

A main magnet 20, comprising three windings 21, 22' and 23, is provided for operating a contact arm 24 in accordance with the current flowing through the elec-' trode4. A core armature 25, which is'connected to the contact arm 24 by means of the spring 26 and is provided with a dash pot 27, is acted upon by means of the coils 21 to 23, inclusive, for effecting movement of the contact arm 24. The wlnding 21 is connected to the three-phase supply conductor 9 by means of a current transformer 28 in order to be energized in accordance with the current flowing through the electrode 4. The two windings 22 and 23 are differentially wound relative to each other and are selectively connected across the are produced by the electrode 4 in order to so change the setting of the main magnet 20 as to prevent hunting action. The contact arm 24 is fulcrumed at 29 and carries a main contact member 30 which is adapted to engage the contact members 31 and 32 according to the operative posltion of the main magnet 20. The plunger of a dash pot 33 is pivotally connected to the contact arm 24 in order to adjust the speed of its operation.

The switch 15 comprises a wind1ng 34, whichis connected. across the supply conductors 13 and 14 upon engagement of the main contact members 30 and 31, and a core armature-35 which is operated by the winding 34. The core armature 35 is directly connected to two switch members 36 and 37 and two interlock switch members 38 and 39. The two switch members 36 and 37, upon operation of the switch 15, serve to connect the armature 11 across the supply conductors 13 and 14 to efiect rotation of the motor 10 in a counter-clockwise direction. The interlock switch member 38 serves to connect the winding 23 across the arc produced by the electrode 4. The winding 23 is wound to oppose the action of the winding 21 and, consequently, upon operation of the switch 15, the interlock switch member 38 effects a reduction in the strength of the main magnet 20.

The switch 16 comprises a winding 40, which is connected'across, the supply conductors 13 and 14 upon engagement between the main contact members 30 and 32, and a core armature 41 which is controlled by the winding 40. The core armature 41 is directly connected to two switch members 42 plete an energizing circuit for a brake magnet 46 from the supply conductors 13v and 14. The brake magnet 46 completes a dynamic-braking circuit for the armature 11 through a resistor 47 If current above normal value flows through the electrode 4, the energization of T he interlock switch member- 44,

creased current flow through the winding 21 'for operating the contact arm 24 to effect engagement between the contact members 30 and 31. Upon engagement of the contact members 30 and 31, the switch 15 is operated to' so energize the armature 11 as to effect rotation of the motor 10 in a counter-clock: wise direction, consequently, the electrode 4 is raised to reduce the current flow through it.

In case the main magnet 20 were controlled solely by the current flowing through the electrode 4, the magnet 20 would not be operated to separate the contactmembers 30 and 31 and prevent further operation of the motor 10 until a normal amount of current was flowing through the electrode 4. Consequently, the motor 10 and themoving parts of the regulator would overtravel to raise the electrode 4 above the desired point and,'accordingly, produce the so-called hunting action.

In order to prevent overtravel of the various moving parts of the system and the resulting hunting action, the interlock switch member 38 is operated simultaneously with the motor 10 to connect the winding 23 across the are produced by the electrode 4. The winding 23 opposes the action of the winding21 and, consequently, changes the setting of the magnet 20 to effect separation of the contact members 30 and 31 just prior to the obtaining of normal current conditions in the electrode circuit.

If the current flow through the electrode 4 falls below normal value, the energization ofthe magnet 20 is reduced to effect engagement between the contact members 30 and 32. Upon engagement between the contact members 30 and 32, the winding 40 is connected across the supply conductors 13 and 14 for operating the switch 16 toefi'ect rotation of the motor 10 in 'a clockwise direction. The clockwise rotation of the motor 10 lowers the electrode 4 in the furnace to increase the current flow through the electrode circuit. The interlock switch member 44 is operated simultaneouslv with the motor 10 for connecting the winding 22 across the arc produced by the electrode 4. The winding 22 assists the current winding 21 and, consequently, increases the energization of the magnet 20 for so changing its setting as to effect disengagement of the contact members 30 and 32 just prior to theobtaining of normal current conditions in the electrode circuit and, accordingly, preventing hunting action.

In a copending application, Serial No. 287,612, filed April 4, 1919, I have illustrated, described and claimed another furmace-regulator system disclosing other means for preventing hunting action in said system.

Modifications in the system and arrangement and location of parts may be made within the spirit and scope of my invention, and such modifications areintended to be covered by the appended claims.

I claim as my invention:

1. In a furnace-regulator system, the combination with a movable electrode, of means comprising a main magnet having three windings for operating said electrode, one of said windings being energized in accordance with the electrode-circuit conditions and two of said windings being differentially-wound and selectively energized to prevent hunting action.

2. In a furnace-regulator system, the combination with a movable electrode, a motor for raising and lowering said electrode, and two switches for operating said motor in a forward and in a reverse direction, of a main magnet having a current winding for selectively operating said switches to maintain a constant electrode arc, said magnet also having two differential windings selectively operated by said switches to prevent hunting action.

3. In a furnace-regulator system, the combination comprising a movable electrode, a motor for raising and lowering said electrode, means comprising a main magnet for operating said motor to maintain a constant electrode arc, and means comprising two diflerential windings for changing the setting of said magnet .to prevent hunting.

action.

4. In a furnace-regulator system, in combination, a movable electrode, means comprising a main magnet for operating said electrode in accordance with the value of the current flowing through it, two differential windings connected to the electrode circuit and operating on said magnet, and means for selectively energizing said differential windings to prevent hunting action.

5. In a furnace-regulator system, the combination comprising a movable electrode, means for raising and lowering said electrode, and control means comprising a main magnet for governing the operation of said first-mentioned means, said magnet having a winding energized in accordance with the value of the current flowing through the electrode and two differential windings selectively connected across the electrode arc to prevent hunting action.

6. In a regulator system, the combination comprising a movable member, a supply circuit connect'ed'to said member, means for operating said member and comprising an electromagnet having a winding energized in accordance with the .Value of the current flowing through the supply circuit and two difierential windings selectively connected value of the current flowing through it,

and two differential windings co-operating with said magnet to prevent hunting action.

8. In a furnace-regulator system, the combination comprising a movable electrode, means for operating said electrode in accordance with the value of the current flowing through it, and means comprising two windings selectively connected to the electrode circuit for preventing hunting action.

9. In a furnace-regulator system, the combination with a movable electrode, a motor for raising and lowering said electrode, and two switches for operating said motor in a forward and in a reverse direction, of a main magnet having a winding energized in accordance with the value of the current flowing through the electrode circuit for selectively operating said switches, said magnet also having two differential windings selectively connected to the electrode circuit by said switches for changing the setting of the magnet to prevent hunting action.

10. In a furnace-regulator s stem, the

combination comprising amovab e electrode, a motor for raising and lowering said electrode, and means comprising a main magnet for operating said motor to maintain a con stant electrode arc, said magnet having three windings, one of said windings being energized in accordance with the value of the current flowing through the electrode and two of said windings being differentially wound and selectively connectedacross the electrode arc to prevent hunting action.

11. In a furnace-regulator system, the combination comprising a movable electrode, and means comprising a magnet having three windings for governing the operation of the electrode, one of said windings being energized in accordance with the value of the current flowing through the electrode and two of said windings being selectively connected across the electrode arc for cooperating with the first winding to prevent vember, 1919.

CLARENCE A. BODDIE.

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