US1480908A

US1480908A - Control of arcing electrodes

Info

Publication number: US1480908A
Application number: US507706A
Authority: US
Inventors: Edward H Horstkotte
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1921-10-14
Filing date: 1921-10-14
Publication date: 1924-01-15
Anticipated expiration: 1941-01-15
Also published as: GB202063A; FR556728A; DE385656C

Description

Jan. 15 1924. 1,480,908

E. H. HORSTKOTTE CONTROL OF ARCING ELECTRODES Filed Oct. 14. 1921 Inventor: Edward H. Horstkotte,

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P atented 15, 1924.

" lpplication filed Octobeffll, 1921. Serial No. 507,706. 1

To all whom it may concern." Be it known that I, EDWARD H. Honsr- KOTTE, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Control of Arcing Electrodes, of which the following is a specification.

' My invention relates to an improved control for arcing electrodes. Although the invention is particularly useful in the control of the arcing electrodes of an electric furnace, the invention is not necessarily limited to the control, of fur nace electrodes, but may also be used in the control of other electric translating devices as well.

In prior electrode controlt arrangements, electromagnetic switch mechanism has been provided for controlling the arcing relation' of the electrodes and the switch mechanism has been automatically operated to effect the control" of the electrodes in response to a condition of the arcs supported Due to the self-inducby the electrodes.

, tion of switch electromagnets and the metromagnetic switch mechanism, and the in-- chanical inertiaof the movable elements of the switches, the control of the electrodes has been tardy and thereis also a tendency to cause' overrunning. Electroresponsive means such as electric motors have heretofore been provided for regulating the electrodes under the control of the said elecertiaand selfinduction of the motors has been added, to thestardyeffect and the tendency to overrunning.

One of the objects of the invention'is to eliminate the electromagnetic switch mechanism heretofore provided. in arrangements for controlling electrodes and other translating dev1ces,.and to minimize the 'tardy effect and the tendency to overrun ning, so that. the electrode or other translating device will be governed practically simultaneously with the occurrence of the electrical condition or conditions which make desirable the control of the electrode or other translating device.

In carrying my invention into effect as applied to the control of the arcing electrodes of an electric furnace, I provide an electric valve for controlling the arcing relation of the electrode. The electric valve may be of an electron discharge type, such 1,4sb,9os Free.

Arm-rot CQNTBOL OF ABCING valve is practically simultaneous with the occurrence of the electrical condition which makes necessary a regulatien of the electrode. In the embodiment of my invention which I have selected for purposes of illustration, the electric valve controls the energization of an electrode motor by.controll1ng.the energization of a generator 'supplyin current to the motor, and although t e arrangement which I have thus selected has certain'important advantages,

invention can be carried out by other means. 7

F or a better understanding of the invention, reference is. had to the accom anying drawing in which T have shown or pur- V poses of illustration the particular embodi- "I conceive that the broad features of the ment'of the invention above referred to.

support arcs for heating the bath contained in the furnace.

The separately excited di-' redt

current motors

14, 15 and 16 are pro- "vided as the electroresponsive means for controlling the arcing relation'of the electrodes 10, 11 and 12 respectively. The energization of these electrode motors is controlled by means comprising the electric valves 17,-18 and 19 respectively. Theelectric valves shewn are of the electron discharge type, in which a hot cathode 2O cooperates with the plate or anode 21 within a container 22. A hot cathode electron discharge device such as a kenetron is satis factory for the purposes of my invention. The electric valvesare connected so as to be responsive to..the electrical condition of e the are supported by the electrode controlled by the valve. Thus, the valve maybe responsive'to the flow of current in the circuit of the electrode controlledthereby, and for controlling the electrode in response to this electrical condition, I have provided

current transformers

23, 24 and 25 for the valves former. 1 Thus, for example, the hot cathode is connected across a portion "of the secondary windings of the current transformer 23 and a resistor 26 is included in the hot cathode circuit so as to regulate the heating effect and thereby the current in the plate circuit. By means of the resistors in- Y cluded, in the hot cathode circuits of the electric valves, the operation of each electrode motor may be adjusted with respect to the other electrode motors, so that after having, been adjusted, the electrode motors will be caused to cooperate to regulate their respective electrodes in the manner desired.

Instead of employing the plate current of a valve or rectifier to directly control its respective electrode motor, I prefer to control the electrode motors by controlling the energization of separately excited

direct current generators

27, 28 and 29, each having its armature directly connected to supply the currentfor the armature, of its respective electrode motor. ,These generators may all be mounted on bne shaft and be driven by an alternating-current motorv 30 energized from the source of supply 31 through the transformer 32, to which the furnace electrodes are also connected' Each of these generators is provided with a field winding supplied with current from an exciter 33mounted on the shaft of the alternating current driving motor 30 so as to be driven therefrom. The -exciter also supplies the current for the separately-excited fields of the electrode motors. The generator 27 is provided with a shunt field 34 which" is energized by the platecurrent of the rectifier 17, and this'shunt field 34 is'diiferentially wound with respect to the shunt. field 35 of the generator. The generators 28 and 29 "are provided with simila r fields and are controlled in a similar manner. The arrangement is such that when the current in the circuit of the electrode 10 is substantially normal, the two fields34 and 35 substantially neutralize each other so that the voltage supplied to the armature of "the electrode motor 14 is practically zero value, but in case the current should either increase 7 or decrease from the predetermined normal,

the value of the voltage and the direction of the current supplied to the armature of the electrode motor-'14; will be such that the motor will be caused-to practically simultaneously operate the electrode 10 to such a position that the condition in the arc circuit of the electrode is automatically and quickly brought back to normal.

As thus constructed and arranged, the operation of my invention is as follows: Assume that the equipment is operatin and that the resistors in the cathode circults of the rectifiers have been properly adjusted, the value of current supplied to the separately excited fields of the generators and .the value of current supplied to the sepa- 'rately excited fields of the motors from the exciter 23 have been adjusted so that a normal; condition of the arcing relation of the electrodes has been established, and that it is desired that this normal relation be maintained. Assume that the current in-th'e circuit of the electrode 10 increases above 1 ,the generator 27 will also be increased.

This will destroy the balance between the separately excitedfield 35 and the field winding 34, the field winding 34 will now predominate, thereby causing the generator 27 to build up practically simultaneously a .voltage corresponding in value and direction to the increase in the current of the circuit of the electrode 10 The armature of the electrode motor 14 will be simultaneously energized to'operate the electrode 10 to raise the electrode until the value of the current in the electrode circuit becomes the normal value which it is desired shall be maintained. I

In case the current in the electrode circuit decreases below the predetermined normal value, the cathode 20 will be heated to a correspondinalyr less value, the energization of the field inding 34 will be correspondingly decreasedfandthe field winding 35 of the generator '27 will nov'i predominate .to reverse the current supplied by the generator to thereby cause the motor '13 to-,lower the electrode, 10 until a stable condition is restored.

It will be apparent from the above that the entire arrangement is very sensitive to changes in the electrical conditions of the arc. supported by the electrodes. The adjustment of the electrodes is effected substantially coincidentally with the occurrence of the electrical condition which makes necessary an adjustment of the electrodes. It will also be observed that the electrode motors are prevented from overrunning,

since the motors will operate in each direction to a limit determined by the value of the voltage induced in the secondary of the corresponding ,current transformer:

Furthermore, the motors will operate as regenerative braking generators *returning energy to the supply circuit in case the 6 generated voltage of the motor should at any time be greater. than the voltage of its respective generator.

. It will be understood by those skilled in the art that the electrical condition of the arcsupported byone of the arcing electrodes has an effect on the electrical condition of themes supported by the other electrodes of the furnace, so that the adjustment of one electrode will be accompanied by the practically simultaneous adjustment ofthe other electrodes in case the adjustment of one electrode makes necessary theadjustment of the'other electrodes to restore the normal condition initially determined upon. 0 1 It will be observed that since the energy supplied to the furnace electrodes and the 2 electrodes to energy for driving the electrode motors is all taken from the source of supply 31, a failure, of said source will not cause the I be lowered .into the ;furnace bath.

, In accordance with the provisions of the patent statutes, have described the prin-. .ci lo of operation of my invention, together 0 w1th the apparatus which I now consider to represent the best embodiment thereof,

but I desire to have it understood .that the apparatus shown is only illustrative: and that the inventionv may be carried out by 5 other rfieans. r

0 What I claimas new and desireto secure by Letters Patent of the United statea'isz 1. The combination with. an electrode adapted to support an arc, of means comprislng an electric valve for; regulating the arcing relation of the said, electrode, and donnections whereby the said valve regulates the arcing relation of said electrdde in accordance with an electrical condition of the 15 arc supported by. said electrode.

as prism 2. The combination with; an electrode adapted to su port an arc, of an electric valve connecte tobe responsive to an electrical condition'of the arc supported-by said 1 electrode, and electro-responsive means controlled by said valve for regulating the arcing relation of the said electrode.

' 3. The combination with an electrode adaptrzyd g an electric valve for'regulat' the arcing relation of the said electrode, and

connections wherebythe' said valve regulates the arcing relatiom of said electrode in #00 supported by the electrode.

accordance wit the current in the are adapted to support an arc, of means comprising an electron discharg device for regulating the ,ar'cing relation of the said 5 electrode, a current transformer having its to support an arc, of means com- 7 4. The combination with an electrode primary in the circuit of said electrode and its secondary connected to the said device, 5

and means controlled by the' said device for regulating the arclng relation of said electrode. v

5. The combination with an. electrode adapted to support an arc, of anv electric motor for controlling the arcing relation of said electrode, an electron discharge device for controlling the said motor, and connections whereby the said device controls the operation of said motonin accordance with the conditions in the circuit in which said electrode is included.

' motor for controlling the arcing relation of said electrode, an electron discharge device and connections whereby said device controls the direction and the limit of operation of saidmotor in accordance with conditions in the circuit which the said electrode.

is included. V A

8. .The combination with an electrode adapted to support an arc, of an electric motor having a/ field and an armature controlling the arclng relation of said electrode, an electron discharge device, and connections whereby the said device controls therelative direction of the field and armature currents of said motor responsively to a condition of the arcing circuit of said elect-rode. I I

9. The combination with an electrode 6. The combination with an electrode adapted to support an arc, of-an electric 1 motor for controlling the arcing relation of said electrode, a ierator for. supplying current to the sai motor, an electron dis-- charge device and connections whereby the said device controls the current supplied by I the said generator to the said motor in accordance with a condition of the arcing cir;

cuit of the said electrode.

10. The combination with an electrbde 3 adapted to support anarc, of an electric motor for controlling the arcing relation of said electrode, a nerator for supplying current to the sai motor, an electron dis--- charge device, and connections whereby the said device controls-the voltage and the di-L rection of current supplied by the said generator to the said motor in accordance with a condition of the arcing circuit of said electrode.

- 11. The elimination with an electrode 1 adapted to support an are, of a separately excited motor for controlling the arcing relation of said electrode, a separately excited generator for supplying the current to the armature of said motor, an electron dis charge device and connections whereby the said device controls the voltage and the direction" of current supplied by the said generator to the said motor in accordance tions whereby the said electron discharge device controls the direction and the limit of operation of the'said motor in accordance with a condition of the supply of en- "ergyto the said translating device.

13. The combination with an alternating current supply circuit, of an electric translating device connected to be supplied with current from the said supply circuit, a direct current motor for regulating the said device, a h eated cathode electron discharge device, and connections whereby the said electron discharge device controlsthe energization of the said motor in accordance with the current taken by the said translating device.

14. The combination with an alternating current supply circuit, of an electric translating device connected to be supplied with current from the said supply circuit, a direct current motor for regulating the said device, a direct current generator connected to supply the current for the said motor, a

heated cathode electron discharge device, and connections whereby the said electron discharge device controls the voltage and the direction of current supplied by the said generator to the said motor in accordance with the current taken by'the said translating device. x

15. A regulator for an electric arc furnace having a-p1urality of cooperating elec trodes connected to an' alternating current supply circuit, comprising a separate direct current motor for regulating the arcing "relation of each electrode, a separate direct current generator for supplyingthe current to each of said electric motors, a separate heated cathode electron discharge device for controlling each of said generators, and connections whereby the said devices control their respective generators in accordance with the current passing through their re:

spective electrodes. p

In witness whereof, I have hereuntoset my hand this 13th day of October, 1921.

EDWARD HORSTKOTTE.