US1796069A - Method of and apparatus for breaking electric circuits - Google Patents

Description

March 10, 1931. s M VIELE METHOD OF AND APPARATUS FOR BREAKING ELECTRIC CIRCUITS Filed July 15, 1

4 Shootshoet l abbou 1 S. M. VIELE March 10, 1931.

METHOD OF AND APPARATUS FOR BREAKING ELECTRIC CIRCUITS Fil y 1925 4 Sheets-Sheet 2 FIG. 3.

FIELE.

F'IQ. 4.

March 10, 1931. I 5 M V|ELE 1,796,069

METHOD OF AND APPARATUS FOR BREAKING ELECTRIC CIRCUITS Filed July 15, 1925 4 Sheets-Sheet 5 FIG-10.

S. M. VIELE March 10, 1931.

METHOD OF AND APPARATUS FOR BREAKING ELECTRIC CIRCUITS Filed July 15, 1925 4 SheetsSheet 4 FIG- 11 Elm/0011M Patented 1931 I i v UNITED STATES PATENT OFFICE snvns'rnn u. vim, or AL'I'OONA, rmmmvmm, assxonon. 'ro Emmi: umro contrary, a CORPORATION or NEW YORK 'mHOD AND APPARATUS FOR BREAKING ELECTRIC CIRCUITS Application filed July 15,

In breaking electric circuits, involving large or abnormal flows of energy, it is customary to form an initial are at the start of such rupture, and then extend or lengthen 8 this are until it finally breaks; the amount of extension necessary to accomplish this de pending on the voltage, current and characteristics of the circuit involved.

, The difiiculties with such devices are the 10 slowness with which the arc is extended'in the simpler forms and the difiiculty of maintenance and initial expense of the devices giving more rapid o eration. This is particularly so in case 0? high voltage or large current capacities.

The present invention contemplates the extension of the are by forcing motion of the are between diverging termini through the action of a magnetic field so as to extend the arc to the breaking point. Thus the entire movement, or extension of the arc, after its initial formation is accomplished electrically and magnetically without any mechanical movement of the parts whatever.

A difliculty with preceding devices, where the terminals have been spread mechanically, so as to extend the arc and the arc has been moved as extended primarily through the action of a current of air induced by the heat of the arc, arises from the fact that the termini of the arc tend to lag in their movement so that the arc in its final shape is very much bowed and is thus objectionable in that the arc in this shape may collapse, thus establishing a shorter arc and delaying the final break. Furthermore, under conditions of high wind, this delay in interruption, due to the lagging of the termini, often permits the are being blown by the wind into parts of the equipment, such as an adjoining pole, with resulting injury to the interrupting device and perhaps to other electrical equipment on the circuit, such injuries being usually so serione as to interrupt the general service of the apparatus. The lagging termini of the arc with the bowed center, representing as it does only the velocity of the heated air, accompanies a slowness of operation where speed is the real objective. If, therefore, the

arc can be maintained approximately straight 1925. Serial No. 48,780.

spreading terminals, this movement being entirely electrically and magnetically induced and with no more lag than is inherent in the design of the equipment. In as much as positive movement of the arc is obtained through these forces and as these forces are capable of adjustment or variation in the orignal design of the device, ver rapid extension of the arc can be obtaine In accomplishing the invention two coils are formed, these coils being wound with overlapping off-set turns, the turns being slightly separated from each other and the edge of the combined coils being slightly curved forming a space or gap between the opposing edges of the coils progressively increasing in width. The are is initially formed above the bottom of these coils extending from the edge of one coil to the other and preferably prior to the timethis arc is formed a magnetic field is established by the coils below the are. The coils bein wound in the same direction a magnetic ld flux from each coil moves in the same direction in the space between the coils. This flow of magnetic flux is confined, in a large measure, to the space between the coils below the are because the portions of the coils above the are are not embodied in the electric circuit. Further, the, local magnetic field established by the arc itself forms a magnetic flux or force which, operating in conjunction with the magnetic flux formed by the coils of the termini adds to the preponderance of the magnetic field below the arc, these magnetic forces causing the arc to move rapidly upwardly between the spreading or diverging terminals formed by the terminal coils. This movement of the arc is also assisted slightly as it is in common practice by the air movement due to the heating of the arc. The coils are spread sufficiently at their upper ends to tit) so extend the are as to break it under any conditions to which the breaker is intended to be subjected. The coils forming the termini are also far enough apart at the coils the flow of the field of each coil is in the same direction through the space. This magnetic force in itself affects a movement of the are by reason of its preponderance below the are but in the present instance by making the direction of the fiow of the field of the are below the arc in the direction of the flow of the fields of the termini the mag netic field of the arc itself augments the force of the fields from the termini in accomplishing the movement of the are between the diverging termini. This is made morepronounced because the direction of magnetic flow of the fieldof the are above the arc is in opposition to the direction of flow ofv each terminus is very much greater immediately adjacent to the terminal coil than it is at points more remote in the space between the coils. Consequently the preponderance of magnetic action on the arc is adjacent to the termini of the arc and this tends to speed up that part of the are which in prior devices has tended to lag and consequently maintains the arc in an approximately straight line, or possibly in a line sagging slightly at the center.

It will be noted that the coils formed in the termini below the initial point of form ing the are have some inductive reactance and this inductive reactance increases as the turns in the circuit are increased. Thisincreased reactance as the arc progresses is utilized in reducing the voltage 'ejfi'ect across the arc and thus reduces the voltage which is to be interrupted and thus hastens the breaking of the are. This introduction of reactance progressively in circuit also diminishes the flow and thus progressively reduces the current up to the final break. Hitherto this has been accomplished ordinarily in a series of steps, most of the steps involving considerable complication of means and moving mechanical devices.

In order to strengthen the magnetic field in the later port-ions of the movement of the are it is desirable to supplement the terminal coils with short-circuited secondar coils inductively coupled with the terminal coils, said secondary coils being arranged at the back of and in the same plane with the termi nal coils. These secondary coils are slightly above the initial position of the arc and extending over the area adjoining the primary coils are inductively coupled with the primary coils to a relatively minor degree with the arc in its initial stages. With this relatively minor inductive coupling and the length of electrical path of such short circuited secondary coils, the inductive reactance of the primary coils is preserved at the initial position of the arc in a major manner and this occurring when the arc path is rela tively short, the current fiow relatively large and the termini of the are exposed to the maximum magnetic field intensity.

As the arc progresses and the length of the arc is increased, the current flow is decreased and the magnetic field at the intersection of the arc and the center line of the gap is decreased. Also under these conditions the inductive coupling with the secondary coils per unit of currentfiow increases, reducing the inductive reactance of terminal coils and increasing the magnetic field due to the interaction of the secondary coils. Thus in the initial stages of the are where the arc lies in a relatively strong magnetic field throughout its entire path, the maximum inductive reactance of the terminal coils is retained with less strengthening effect from the secondary coils, whereas when the length of arc is increased in its final stages the inductive reactance per turn and per unit of current flow is reduced and the strengthening effect of the magnetic field from the secondary coils is increased under conditions where such strengthening effect is most needed. There is, therefore, per unit of current flow a substitution of useful magnetic field for induc- .t'ive reactance per turn of primary coils and Jsnch substitution is made in an incremental in the structure in a plastic material, such as concrete, so as to maintain them rigidly in proper relation, preferably leaving only the portion of the coils immediately at the edges of the termini exposed.

I also prefer to form initial arcs adjacent to each termini through the action of a switch, gradually lengthening these arcs toward the center until they join and the magnetic field built up with the opening of the main switch follows up the initial arcs and the final arc so that immediately upon the joining of the separated arcs there is a flash movement of the arc upwardly through the ga with the final break.

y invention contemplates an improved step switch for circuit breakers particularly desirable with this manner of extendin and breaking the arc. Features and details of the invention will appear more fully from the detailed specification and claims.

The apparatus forming the subject matter of the invention and by means of which the method may be practiced is illustrated in the accompanying drawings as follows Fig. 1 shows a side elevation of the device, the plastic concrete blocks being indicated in dash lines exposing the coils.

Fig. 2 is a section on the line 2-2 in Fig. 1.

Fig. 3 a section on the line 33 in Fig. 1.

Fig. 4 a view showing the coils of one of the terminals.

Fig. 5 an enlarged view showing the manner of forming the coils.

Fig. 6 an end view of one 'of the coils.

Fig. 7 a top view of the coils.

Fig. 8 a plan view of an operating device for a three pole circuit breaker.

Fig. 9 a side elevation of the secondary switch terminal.

Fig. 10 a bottom view of the secondary switch terminal.

Fig. 11 an enlarged broken sectional view of the switch.

Current is brought to the device through conductors l and 2 connected with terminals or )osts 3 secured to or embedded in concrete slabs 4. The concrete slabs are secured by plates 5 mounted on insulated posts 6, the insulated posts in turn being mounted upon a concrete base 7.

lVires 8 extend from the terminals 3 to terminals 9. A primary switch having arms 10 formed of spring plates operate in terminal slots 11 of the terminals 9 in the usual manner'. The switch arms are mounted on an insulated post 12. The post 12 has a shaft extension 13 mounted in ball bearings 14., the ball bearings being carried in a frame 15 mounted on the base 7. Arms 16 extend from the shaft 13 and as shown in Fig. 8 a rod 17 is secured to each arm 16. The ends of the rods are secured to arms 18 mounted. on shafts 19. Gears 20 are secured on the shafts 19 and mesh with a gear 21 arranged between the gears 20. The gear 21 is mounted on a shaft 22 which is connected with any desired or common actuating mechanism for circuit breakers. As shown in Fig. 8 the rods 17 may be secured to a series of arms 16, thus actuating simultaneously a series of breakers as desired, the construction being designed to operate a three-pole circuit breaker.

A sleeve 23 extends upwardly from the insulated base 12, the spring arms 10 being se cured on this sleeve by means of nuts 24. A yielding terminal spring bar 25 has its lower end secured at 26 in the sleeve mounting and extends upwardly through the center of the sleeve. The upper end of the rod 25 is mounted in a ball bearing 27 in the sleeve 23 and a .cap 28 is mounted on the rod above the sleeve.

Switch arms 29 are clamped on the cap 28 by means of a nut 30 on the upper end of the rod. The ends of the spring arms are in the form of loops with a contact end 31 which engages a cam surface 32 of a terminal 33. In the operation of the switch with the initial rotation of the shaft 13 the primary switch arms 10 are moved out of engagement breaking the direct electrical connection between the conductors through the wires 8 and terminals 9, After the arms 10 have moved a pre-determined distance the s ring force of the rod 25 overcomes the retar ing resistance of the engaging ends 31 in the terminals 32 and the spring arms of the secondary switch then move with a spring-actuated movement due to the tension on the rod 25 breaking the connection between the terminals 32. In order that the break between the spring arms and the terminals may be forced to take place at a pre-determined point I prefer to provide arms 34 which operate in the loops of the spring arms 29 and thus engage these spring arms positively at a fixed pointin the rotation of the arms 10 so that the secondary break must, of necessity, take place not later than a predetermined point in the rotation of the switch.

Coils 35 are connected between the terminal 9 and the terminal 33, these coils having their axes at approximately right angles to the plane between the arc forming gaps of the device. These coils are continued in coils 36, the edges 37 of which gradually diverge from each other upwardly from their nearest position at the terminals 32. The edges 37 of these coils form the terminal points of the are as it is advanced upwardly as hereinafter described and these edges extend from the face of the concrete slab in which the coils are embedded, the edge of the concrete slab being indicated at 38 in Fig. 1. 4

From the preliminary description of my method it is believed that the operation of the .apparatus will be readily understood. With the breaking of the direct connection by the disengagement of the spring arms 29 arcs are formed between the terminals 32 and the immediately adjacent parts of the spring arms. As the arms swing through the action of the rod 25 and the moving switch these preliminary arcsmove upwardly maintaining the shortest path between the terminals and the switch arms, finally meeting at the upper ends of the switch arms and then bridging the entire space or gap between the termini with a single arc. The are at the edges moves from turn to turn of the coils 36 as they become in the same direction as the magnetic flow of and beneath the are which is formed in bridgmove upwardly.

ing the space between these edges as incident to the direction of flow of the current and there is, therefore, a resultant preponderance of the density of magnetic field under the are, which acting on the arc compels it to As the arc is thus forced upwardly the turns of the coil 36 are successively brought directly into the path of the current through the arc and the magnetic field immediately belowthe arc progresses upwardly as the arc progresses and as this progresses the inductive reactance of the coils become efi'ectiveto reduce the current in the arc.

In order to make more effective the force of the magnetic field adjacent the are as the arc is extended and the current becomes reduced I prefer to supplement the terminal coils 36 with short circuited secondary coils 39. These coils are above the portion of the terminal coils and are so arranged that the parts of the terminal coils 36 adjacent to the extended arc are made more effective by means of the secondary coils. These secondary coils are inductively coupled with the primary coils 35 and 36 and the effect of this is to increase the magnetic field in the space between the terminals and to decrease the inductive reactance in the parts of the terminal coils forming the coils 36 which are more remote from the extended arc. In consequence the density of the magnetic field set up by the parts of the terminal coils 36 adjacent to the arc is increased as the arc is extended and thus tends to become more effective in its forcing action on the are with the widening gap. At the same time they tend to reduce the inductive reactance that would otherwise exist in the parts of the terminal coils which are remote from the arc during this period when the current flow is reduced. The provision of the secondary coil in inductive relation with the primary coils 35 and 36 also assures the insertion of the inductive reactance of these coils in the circuit as the arc progresses in a very smooth and progressive manner.

What I claim as new is 1. In an electric circuit breaker, the combination with are forming devices of magnetic field forming means for the arc comprising overlapping coils with axes acrossthe axis of the arc. y

2. In an electric circuit breaker, the combination with are forming devices, of magnetic field forming means, for the arc-formed of overlapping coils with-axes across the axis of the arc and placed successively in series 7,

5. In an electric circuit breaker, the combi-" nation of arc-forming termini formed with coils having successive turns at the edges of the termini and with axes across the plane between the termini; a switch between the termini comprising a primary switch forming a direct connection at the ends of the termini and a secondary switch operating intermediately the coils of the termini; and means for actuating said switches in sequence.

6. In an electric circuit breaker, the combination of arc-forming termini formed with coils having successive turns at the edges of the termini and with axes across the plane between the termini; a switch between the termini comprising a primary switch forming a direct connection at the ends of the termini and a secondary switch operating intermediately the coils of the termini; and means for actuating said switches in sequence comprising a yielding connection opening the secondary switch following the opening of the primary switch. I

7. A magnetic arc blowout for interrupting electric circuits comprising a plurality of blowout coils disposed in overlapping relation along the path of the arc and interconnected to be successively included in the arc circuit as the arc lengthens.

8. A magnetic arc blowout for interrupting an electric circuit comprising an elongated winding having the successive turns of the winding extending along the arc path to besuccessively included in circuit with the are as the arc lengthens and disposed so as to supply a magnetic flux transverse to the arc path and thereby magnetically drive the arc along the successive turns of the winding.

9. A magnetic arc blowout for interrupting an electric circuit comprising an elongated winding disposed along the path of the arc and connected so that the turns of the winding are included successively in the arc circuit as the arc lengthens, the said turns of the winding being spaced apart and skewed relative to the axis of the winding so as to supply a magnetic flux transverse the arc path to drive the are along the successive turns of the winding.

10. A magnetic arc blowout for interrupting an electric circuit comprising a conductor electrically connected to the circuit at one end and disposed adjacent to the arc path to receive one end of the arc, said conductor being formed in a succession of turns disposed in spaced relation to supply a magnetic flux transverse the path of the arc to thereby drive the endof the arc along the successive turns of the conductor and simultaneously stretch the arc and include a progressively increasing reactance in the arc circuit.

11. A circuit interrupter comprising relatively movable switch members, a magnetic arc blowout therefor including an elongated winding disposed adjacent to and connected with one of the switch members to receive the 26 are therefrom upon relative movement between the switch members and thereby connect a portion of the turns of the winding in the arc circuit, the turns of the said winding being spaced apart and arranged in over- 30 la ping relation for supplying a component of ux transverse the arc to drive the end of the are along the successive turns of the winding.

my hand.

SYLVESTER M. VIELE.

12. A magnetic arc blowout for interrupt- 85 ingan electric circuit comprisin an elongated winding disposed adjacent t e path of the arc and having a corresponding portion of the successive turns of the winding exposed to receive the end of the are as the arc lengthens, the successive turns of the winding being spaced in overlapping relation for supplying a component of flux transverse the are path to drive the end of the arc therealong.

13. A. magnetic arc blowout for a circuit interrupter comprising a core of insulating material, a winding disposed on said core with the successive turns on at least one side of the core at an acute angle with respect to the axis of the core and spaced in overlappin relation to form a path for the are along sai blowout.

14. A circuit interrupter comprising relatively movable switch members and a magnetic arc blowout therefor including a pair of elongated windings each having one end electrically connected to a corresponding one of the switch members, said windings having the successive turns thereof skewed with reso spect to the axis of the winding and overlapping and each located to form an arcing ter- .minal for the corresponding switch member and arranged so that the current flowing through the successive turns of the windings 66 set up a magnetic flux transverse to the arc to

Images