US1551355A

US1551355A - Habby a

Info

Publication number: US1551355A
Authority: US
Publication date: 1925-08-25
Anticipated expiration: 1942-08-25

Description

Aug. 25, 1925. 1,551,355

H. A. wlNNE ELECTRIC FURNACE CONTROL SYSTEM AND APPARATUS F-iled Oct. 3, 1925 Ivm/enter'. Harry A. Wmv-1g ''Hia Attorney.

Patented Aug. 25, 1925.

UNITED STATES kPATENT FFICE.

HARRY A. WINNIE, OF SCHENEGTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION 0F NEW YORK.'

ELECTRIC-FURNACE-CONTROL SYSTEM AND APPARATUS.

Application ma october a, 192s. serial No. 666,242.

To all whom z't may concern:

Be it known that I, HARRY A. W1NNE,-a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvementsfin Electric- Furnace-Control Systems and Apparatus, of which the following is a specification.

This invention relates to the control of electric arc furnaces and the object of my invention is to maintain the current supplied to a plurality ,of arcs at a predetermined relation with respect to .the voltage ofthe arc circuit as well as to maintain the voltage across the'individual arcs in a predetermined relation by vmeans of automatic electrode operating motors of simple, inexpensive and sturdy construction.

In my Patent No. 1,310,109, issued July 15, 1919, I have described an electric furnace control s stem and apparatus in which one of the -filrnace electrodes is operated byr an electric'motor controlled by electromag netic switches and relays to cor'rect for variations of current in the arccircuit, and avsecond electrode is likewise operated by an electric motor controlled by electromagnetic switches and relays to correct for unbalance in the voltage drops across the two.

electrode arcs. For large furnaces such con-` trol apparatus has provenentirely satisfactory but for smallerfurnaces the initial costl ofthe motors, switches and relays has formed such a large proportion of the installation charge as to leave much to be desired in the way ofl a more simplel and inexpensive automaticr electrode control. My present invention contemplates a very much simplified control in which all electromagnetic switches and relaysl are eliminatedA and the electrode 'operating motor` itself is at all times responsive to the electrical conditions of the arc circuitbeing controlled, whereby advantageous features of construction and arrangement are obtained.

In accordance with my present invention,

the electrode' o erating motors are of the reciprocating e ectromagnetic type operating through a pawl and ratchet or other suitable intermittent linear to'intermittent rotational motion transforming `mechanism to raise or lower the electrodes in a step by step 'mannen and each .motor is provided with -two opposing windings respectively energized responsively to `the electrical `base of the furnace.

characteristics y,of the arc circuit which it is deslred to maintain in a predetermined relation. With the two electrical characteristics in the desired predetermined relation, the opposing windings of each electrode operating motor are designed to be equally energized and hold the reciprocating armature of the motor inxequilibrium. But when either of the characteristics varies from the desired relation, the winding energized by the predominating characteristic operates to ralse or lower one of the electrodes in a series of step bystep movements until the arc circuit is changed sufficiently to a ain bringv the characteristics into the deslred relation.

The novel features of my invention are pointed out with particularity in the appended claims and the present preferred embodiment of my invention 1s illustrated diagrammatically in the accompanying drawing in which, 1 represents an electric .furnace of conventional form for subjectlng a charge 2 to the heating action of the electric arcs maintained'between the pair of

movable electrodes

3 and 4 andthe charge, or if the charge is nonfconducting, between the movable .

electrodes

3 and 4 and the sta tionary electrode 5 which is located at the In the form of electric furnace shown in the drawing, the two arcs terminating `in

electrodes

3 and 4 are connected in a series circuit from supply line 8 through conductor 46, electrode 3, charge 2, electrode 4, and conductor 7 to the other supply Vline 9. The arcing relation of electrode 3 is regulated by reciprocating electromagnetic motor 1() to maintain the current through the arc4 circuit in adesired relation with the voltage supplied to the arc circuit from lines 8 and 9, while the arcing relation of electrode 4 is'regulated by reciprocating electromagnetic motor4 11 to maint-ain electrode 4 at the samefarcing distance from the charge as electrode 3.

The operating motor 10 for electrode 3 lcom rises a pair of

armatures

12 and 13 ioo straddling the stationary pin 18 in such manner that one of the pawl tongues is thrown into engagement with the ratchet wheel 19 to rotate the wheel a part of a. revolution in a clockwise direction when the connecting rod 14 is reciprocated by winding 15 and the other pawl tongue is thrown into engagement to rotate the wheel 419 a part of a revolution in a counterclockwise direction when lthe rod 14 is actuated by winding 16. The ratchet wheel 19 is mechanically connected through suitable gearing, the drawing showing a speed reducing gearing, to act on the screw threaded rod 20" to raise or lower the electrode. The gearing is shown in very diagrammatic -form since .the particular type of gearing is not of the es sence of the invention.

Operating winding 15 of motor 10 is en ergized responsively to the voltage applied to the arc circuit by having one terminal connected directly to the conductor 7 as shown `and the other terminal connected through the normally closed switches 2l and 23 to the other conductor 6, while winding 16`is energized responsively to the current in the are circuit by being connected di- /rectly to the secondary of a current transformer 25 in one ol' the lines, line'6 as shown. Normally

open switches

22 and 24 are closed during certain phases of the operation of motor 10 to short circuit wind ing 16. A variable resistance 26 is provided for shunting at lwill the secondary of the current transformer so as to vcalibrate the winding 16 for operation in response to any desired value of current in the arc circuit. While l have shown the winding 16 as 'energized .from the secondary of a current transformer it will be understood that any other suitable arrangement may be provided for ener'gizing winding 16 proportionally to. the current taken by the electric furnace. y

The switch 21 is pivoted at a point intermediate its ends and is biased to the closed position in any suitable manner as by means of the spring shown in the drawing. The switch 22 is also pivoted at a point intermediate its endsand is, provided'with a flexible contact as shown to allow continued movement of the switch after the contacts are initially closed. Switch 22 is biased to open position. These

switches

21 and 22 are oppostely disposed with their operating ends in the path of and an e ual distance on either side of the mid-position of finger 27 which is carried by the reciprocating connecting rod 14.

The switch 23 is shown as being of the throw-over type in which the ycircuit controlling blade 28 and the operating arm 29 are individually rotatable about acommon pivot and are connected by the spring 30 one end of which is secured to blade 28 and the other end is secured on the opposite sideof the pivot -to arm 29 so that shifting the spring 30 over thepivot center by a full movement of the operating arm 29 is necessary to operate the switch blade 28 from the closed position shown to the o en position in which the blade rests against the stop 31. Likewise a full reverse movement of the operating arm is also required to again operate the switch blade Jfrom the open to the closed position.' For the purpose of operating switch 23, a finger 32 is located on the reciprocating connecting rod 14 in such a position that it will engage operatingarm 29 and move the arm against the bias of spring 33 and shift the spring 30 over' center 'to open the switch blade 28 near the end of' the operating stroke of the connecting rod when reciprocated by winding 15. Near the end of the return stroke of the 'i connecting nod, spring '33 serves to return operating arm `29 and shift the spring 30 over center to operate the switch blade 28 to closed position. The switch 24 isconstructed the same as switch 23 just described except that it is biased to open position and is operated `by linger 34 on connecting rod 14 to closed position when the connecting rod is reciprocatedby winding 16.

The winding 15 of motor 10 is designed to exert an attractive force on the armature 12 when energized responsively to the normal voltage supplied to the arc circuit by lines 8 and 9vwhich is equal and opposite to the attractive force exerted by winding 16 on armature 13 when energized responsivelytothe desired current flow in the arc circuit. The connecting rod 14 is thus held in equilibrium in the central position shown, and to assist in the centering of the connecting rod under' these conditions,

compression springs

35 and 36 are interposed respectively between the outer ends of

armatures

12 and 13 and two stationary abutments as shown. These springs center the connecting rods'14 not only when the armatures are equally attracted but also when both of the

windings

15 and 16 are .deenergized as will be more fully set forth in connection with the operation of my invention.

It will be observed that reciprocating electromagnetic motor 1l is essentially a duplicate of motorvlO, as motor 11 has the same parts arranged in the same manner as described above with the rincipal exception that the operating windings are energized in a different manner. The ,operating winding 15 of motor 11 is energized responsively to the voltage drop across the arc terminating in electrode 4 since one terminal of the Winding 15 is connected directly to the conductor 7 which connects electrode 4to line 9 and the other terminal is connected through switch 23', switch` 21', and conductor 37 to the stationary electrode 5 which is i'n Contact with the charge 2 in either of which all of the furnace arcs terminate. The other operating winding 16 oi motor 11 is energized responsively to the voltage drop-across the arc terminating in the electrode 3 by having one terminal connected directly to the conductor 8 and the other connected through switch 24', switch 22', and conductor 37 to electrode 5 and the charge 2.

Operation.

As thus constructed and arranged' and with the parts in the respective positions shown in the drawing, the operation of my invention is as follows:

Assume that the furnace has received a suitable charge to be heated and has been connected to receive energy from the lines 8 and 9, but that the

electrodes

3 and 4 have not yet been brought into 'arcing relation with the charge. W'inding 15 of motor 1') and also windings 15' andy 16' of motor 11 will be energized by the Voltage across lines 3 and 9. rThe two windings of motor 11 are equally energized and'maintain connecting rod 14 in equilibrium in the central position since they are ,connected in series across the lines 8 and 9 through the following circuit; from line 8 through conductor 6, winding 16', switch 24', switch 22', switch 21", switch 23', winding 15', and conductor 7 to the other line 9. Motor 11, for the time being thus remains in a balanced condition. But the winding 15 of motor 10 is energized by the voltage of the supply lines through a circuit from line 9, including conductor 7 windingl, switch 21, switch `23, conductor 6, .to the other line 8; The winding 16 is not energized since there is as as yet no .current flow in the arc circuit, therefore winding 1FL operates to lower electrode l3 in the follow ing manner.` The armature 12 is attracted by winding 15 and moves the connecting rod 14 upwards, causing the pawl 17 tofengage ratchet wheel 19 and rotate it a part of a revolution in a clockwise direction to lower electrode 3. Near the beginning of the upward stroke `of connecting rod 14, the pin 27 strikes the operating endof switch 22 and moves the switch to closed position againstA the bias of theopening spring with which switch 22 is provided. Near the end of the upward stroke, pin 32 engages the operating arm 29 and moves the sameupwards against the bias of closingl spring 30 to shift the spring over center and snap the circuit controlling blade 28 into open position. This opens the energizing circuit of winding 15. Thereu on spring-35 which. has been com resse`d y the upward stroke of the connecting rod returns the connecting rod to the central position. Switch 22 remains closed and switch 23 remains open until the'end or the return stroke of the connecting rod when both switches again are returned to their respective open and closed positions as shown in the drawing by their biasing springs. The closure or' switch 23 again energizes winding 15 and motor, 10 operates to further rotate ratchet wheel 19 to lower electrode 3. Thisoperation of motor 10 continues successively until electrode 3 is lowered into contact with the charge, whereupon motor 11 becomes operative to lower electrodey 4 as follows:

When electrode 3 contacts with the charge 2, the operating winding 16' of motor 11 is short circuited since winding A16' is responsive to the voltage between electrode 3 and the charge 2. Winding 15 still beingenergized by the voltage between elect-rode 4 and the charge operates motor 11 in the same manner as just described for motor 10 until electrode 4 is also lowered into contact with the charge. This completes the arc circuit and causes a rush of current from the supply lines. Winding 16 of motor 10, being energized responsively to this current, attracts armature 13 thereby moving connecting rod 14 downward against the pull of winding 15 and raising electrode 3 a short distance, thusA establishing an arc between the electrode 3 and the charge. Near the beginning of the downwardstroke pin 27 opens switch 21 to deenergize winding 15 and remove the restraining upward pull on rod 14. Near the endy of the downward stroke pin 34 engages switch 24 and operates itI to closed position to short circuit and thus deenergize. wind# ing 16. Both

windings

15 and 16 being deenergzed, spring 36 then returns the connecting rod 14 to central positionfand the operation ot' motor 1() is repeated in this manner to raise the electrode 3unti1 the current in the arc circuit is reduced to the desired value at which the' pull of winding 16 is equal and opposite to that of winding 15. It will be observed that when both the

electrodes

3 and 4 are in contact-with the charge, both windings 15' and 16' of motor 11 are .short circuited. As electrode 3 is raised by ever, continues to loperate themotor 11 kto raise the electrode-4 until the voltage drop acrossA the arc terminating in 'electrode 4 equals kthat across the `are terminating in electrode 3, which. condition will be obtained when both electrodes are the same arcing distance from the charge. rThen the

windings

15 and 16 are equally energized and the connecting rod 14 of motor 11 is held in equilibrium.

Vith normal voltage and the desired current flow in the arc circuit, and the voltage drops across the arcs of

electrodes

8 and 4 equal, the respective windings ofl motors 10 and 11.will be equally energized and main= tain their respective connecting

rods

14 and 14 in equilibrium in the central position. From the foregoing, it will be evident that upon a variation of either the voltage or the current of the electrode circuit from the predetermined relation in which windings 15 and V16 are equally energized, motor 10A will become operative to ra`ise or lower electrode 3 to reestablish the balanced relation. As pointed out above, the resistance 26 may be varied at will to change the relation between the voltage and current in the arc circuit at which the windings ot motor 10 will be equally energized. Likewise upon a variation from a balanced relation in the voltage drops across the arcs terminating in

electrodes

3 and 4, motor 11 will become operative to raise or lower electrode 4 to reestablish the balanced relation.' Although I prefer to have 'the motor 11 maintain a balanced relation between the voltage drops of the arcs, it will be understood that should any predetermined unbalanced .relation be desired, suitable variableresistance may be inserted in the circuits of either or both' of the

operatingwindings

15 and 16 to permit adjustment ofthe voltage applied to the windings to any desired values.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with 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 invention can be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. A furnace regulator comprising a reciprocating electromagnetic mechanism for operating a furnace electrode, a plurality of normally opposed operating windings for sai-d mechanism energized responsively to different electrical characteristics of the electrode circuit, and switch mechanism and connections whereby the energization of one of said-windings is varied to permit the predominating winding to change the arcing relation .of the electr/ode when the said electrical characteristics vary from a predetermined relation.

2. A furnace regulator comprising a reciprocating electromagnetic mechanism for operating a. furnace electrode, a pair of nory ratchet mechanism operable in one direction mally opposed operating windings therefor, each energizedv responsively to a different electrical characteristic of the electrode circuit, and switch mechanism and connections whereby the magnetic force of one of said windings is varied to permit the predominating force of the other winding to change the arcing relation of the electrode when the electrical characteristics of the electrode circuit vary from a predetermined relation.

3. A furnace regulator' comprising a pawl and ratchet mechanism mechanically connected to operate a furnace electrode in successive steps in either direction, electromagnetic meanshaving normally opposed operatingr 80 windings for reciprocating the pawl of sai mechanism each way from a mid-position, and connections whereby the energization of the said windings is balanced in response to a predetermined relation between two different electrical characteristics of the electrode circuit.

4. A furnace regulator comprising gearing including a double acting pawl and to raise a furnace electrode and operable in the other direction to lower the electrode, a reciprocating operating memberA for the pawl biased to the mid-position, electromagnetic means for moving the said recip- `rocating member in either direction from the mid-position, limit switch mechanism actuated responsively to the movement of the reciprocating member, and connections wherebyA the energization 'of said electro- 100 magnetic means is controlled in response to a predetermined relation between two different electrical characteristicsv of the electrode circuit to operate the saidelectrode in successive steps.

5. \A furnaceregulator comprising a double acting pawl and ratchet operable in one direction to raise a furnace electrode and operable in the other direction to'lower the electrode, a pair of opposin electromagnets for operating said pawl an ratchet mechanism and'connections whereby upon the energization of one of said magnets predominating the energization of both magnets is successively altered tooperate said electrode in a direction determined by the predominating magnet.

6. A furnace ,regulator comprising a double acting pawl and ratchet operab e in one direction to raise a `furnace electrode 190 and operable in the other direction to lower the electrode, areciprocatingoperatingmemher for the pawl biased to the mid-position, a pair of opposing electromagnets for operating said member, a plurality ofy limit switches actuated responsively tothe Inovement oi said reciprocating member, and connections whereby upon the energization of one ot said magnets predominating the energization of both magnets is successively altered to operate saidelect-rodein a direction determined by the predominating magnet.

7. A regulator for an electrode adapted to be connected in circuit with a source'of electrical energy to support electromagnetic mechanism having'a reciprocating `electric arc, comprising an armature member biased to mid-position and successively operable in one direction to move said electrode to .increase the length of the arc and successively o erable in the other direction to move said e ectrode todecrease,the length of said arc, two operating windings orsaid armature member, one for operating said armature member in one direction responsively to an electrical characteristic-of` the electrode circuit, and the other for operating said armature' memberrin the other direction responsively to another 'electrical characteristic of nace having a plurality ot' arcing electrodes adapted to be connected in circuit-with a source of supply, comprising a plurality of reciprocating electromagnetic motors, each mechanically connected to operate a corre-A sponding Aone of said electrodes and each having two opposingno-rmally energized operating windings, and switch mechanism and connections whereby one winding of one of said motors is deenergized to permit operation of the corresponding electrode by the other winding upon variations from a predetermined relation between the voltage and `current of said arc circuit and one winding of the second motor is deenergized to permit operation ot' the corresponding electrode by the other winding upon variations from a predetermined relation between the voltagedrops across ,the respective arcs terminating in said first and second electrodes.

9. A regulator for an electric arc furnace having a plurality of arcing electrodes adapted to receive currentvfrom a source of supply, comprising a plurality of reciprocating electromagnetic motors each having two opposing operating windings whichmaintain the motor in equilibrium when equally energized and which effect operation of the motor in a direction determined by the predominating winding when the windings arev unequally energized, each of said motors being mechanically connected to ,control the arcing relation of a corresponding one of said electrodes, and connections'wherebyone of the windings of one of the motors is energized responsively to the voltage ofthe source and the other windingis energized responsively to the current through one of theelectrodes, .and one ofthe windings of a second motor is energized responsively to the voltage drop across the arc controlled by the'first motor and the other winding is energized responsively to the voltage drop across the 'arc controlled by the second motor.

,1n witness whereof, I have hereunto set my hand this 1st da ofOctober, 1.923.`

x IARRY A. VVINNE.v

Certicate of Correction;

It is herebycerti'ed that Letters Patent No. 1,551,355 1925, upon the apphcationfof Harry A. Winne, of ySchenectad granted August 25 New` York, 'for `ali improvement in Electric-Furnace-Control Systems and Apparatus, errors appear in .the printed claim 7 after the wor s ecification requiring correction as fol ows': Page 5, line 6,

support insert the words cm electric arc, comprising, and

j line 7, after the word reciprocating strike out the words electric arc comprising an and that the said' Letters Patent should be read with these corrections therem tha-tithe same may conform to the record of the case in thePatent Office Signed and sealed this 29th day of September, A. D.

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KARL F ENNING; -Aing 00m/miniem of Patente(