US2488569A

US2488569A - Circuit interrupter

Info

Publication number: US2488569A
Application number: US557078A
Authority: US
Inventors: Albert P Strom
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1944-10-04
Filing date: 1944-10-04
Publication date: 1949-11-22
Anticipated expiration: 1966-11-22

Description

`Nov. 22, i949 A, P. STROM 2,488,569

CIRCUIT INTERRUPTER Filed Oct. 4, 1944 5 Sheets-Sheet 2 Pfg@ ATTOR N EY Nov. 22, 1949 A. P. STROM CIRCUIT INTERRUPTER 5 Sheets-Sheet 5 Filed Oct. 4, 1944 ATTORNE Patented Nov. 22, 1949 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER Albert P. Strom, Forest Hills, Pa., assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 4, 1944, Serial No. 557,078

21 Claims. 1

This invention relates to circuit interrupters, in general, and, more particularly, to arc extinguishing structures therefor.

A general object of my invention is to provide a circuit interrupter of improved construction which will more effectively interrupt the circuit therethrough than has been achieved heretofore. My invention relates to circuit interrupters in which properly controlled flow in the region of the arc is used to bring about interruption. Where the ilow is produced by a separate energy source, rather than by the arc itself, the iiow is generally more effective, since such flow is independent of the current magnitude, and the interrupter can be made to operate successfully over a larger current range. Self-energized ow usually results in insufficient flow at low currents, and excessive flow and pressures at high currents. On the other hand, self-energized flow eliminates the need of additional sources of energy. It is an object of my invention to obtain most of the advantages of a device having separately energized ow without the use of a separate energy source. A more specific object of my invention is to provide an improved circuit interrupter in which pressure from a pressure-generating arc is stored until it attains a suiiicient pressure to readily effect the interruption of a serially related interrupting arc, at which time the pressure adjacent,

the pressure-generating arc is suddenly released to quickly effect the extinction of the interrupting arc to thereby interrupt the electrical circuit passing through the interrupter. l

Another object of my invention is to provide an improved circuit interrupter in which a pressuregenerating arc is established within a pressuregenerating chamber and an interrupting arc is established within an interrupting chamber with improved means permitting inter-communication between the t'wo chambers upon the attainment of a predetermined rise of pressure Within the pressure-generating chamber.

Another object is to provide an improved circuit interrupter in which the pressure adjacent the pressure-generating arc is utilized for creating a superimposed pressure adjacent the point of initial establishment of the interrupting arc. Also preferably I employ a higher pressure created adjacent the pressure-generating arc to cause a flow of uid under high pressure from the pressure-generating arc toward the interrupting arc, the latter being established in the region of superimposed pressure.

In general, the scheme consists of a pressuregenerating arc in vseries with the interrupting arc,

2 but the pressure-generating arc is located in a chamber separated from that in which the main interrupting arc is drawn. The pressure-generating arc is drawn rst, before the interrupting contacts part. It builds up a predetermined pressure in the Ypressure-generating chamber, which preferably has one wall in the form of a piston held in position by a strong spring, so that as gas is formed the volume of the chamber may expand. Then when pressure reaches a predetermined value a port is opened between it, and the interrupting chamber. The interrupting contact noW opens, and the arc is extinguished by the flow of oil or gas from the pressure-generating chamber. This flo-w is thus essentially independent of current magnitude. On low currents a little longer time is required to store the energy, but the velocity of ow when the contacts open is practically the same for both large and small currents. The flow of gas or liquid toward the interrupting arc is essentially independent of the amperage of the interrupting arc since it is produced by the stored energy within the pressure-generating chamber.

Further objects and advantages will readily become apparent upon a reading of the following specification taken inconjunction with the draw ings, in which:

Figure l is a vertical sectional view through a circuit interrupter embodying my invention and shown in the closed circuit position;

Fig. 2 is a sectional View taken along the line II-II of Fig. l.;

Fig. 3 is a fragmentary view of a portion of the contact structure utilized for establishing the pressure-generating are;

Fig. 4 is. a sectional view taken along the line IV-IV of Fig. 3;

Fig. 5 is an elevational View partially in section of a circuit interrupter embodying a modification of my invention and being shown in the closed circuit posiiton;

Fig, 6 is a vertical sectional view through the left-hand arc extinguishing unit of Fig. 5, the parts being shown in the partly open circuit position;

Fig. 7 is a vertical sectional view through a modied type of circuit interrupter embodying my invention, the parts being shown in the closed circuit position; and

Fig. 8 is a sectional View taken along the line VIII- VIII of Fig. 7 taken on a reduced dimensional scale.

Referring to the drawings and, more particularly, to Figs. 1 4 thereof, the reference numeral I- designates a metallic casing iilled to the level 2 with a suitable arc extinguishing uid 3 in this instance circuit breaker oil. A metallic plate 4 encloses the lower end of the casing I, being secured thereto by any suitable means such as welding 5. The upper end of the casing I is apertured as at 6 and through this aperture an insulating casing I extends having a shoulder portion 8 which seats upon the periphery ofthe aperture 6, a resilient gasket 9 preferably being provided.

The upper end of the insulating casing T is closed by a metallic cap I which is secured threadedly at I I to the upper end of the casing 'I. A metallic cylinder I2 is threadedly secured at `I3 to the lower end of the casing l'I, thelowerendof the cylinder I2 being attached to the plate 4 by any suitable means (not shown) Exhaust apertures 4 are provided adjacent .the lower end of the cylinder I2.

Reciprocally movable within the cylinder I2 .is a piston member I5, in this instance comprising a disc of insulating material. Threadedly Sgcured at I6 to the piston member I5 is an insulating piston sleeve I'I which slides adjacent the inner wall of the cylinder I2. Rigidly secured to the piston member I5, and preferably threaded there.- to at I8 is an insulating piston rod I9, having the upper portion thereof provided with a bore in which slidably moves an enlarged spider portion 2I secured to the bottom of a movable interrupting contact 22. A vcontact actuating member 23 having apertures 24 provided therethrough -is threadedly secured at 25 Vto `the upper portion of the bore 20. Also the upper portion of the piston rod I9 has `a plurality .of grooves .or flutes 26 formed therein, the purpose for which will `appear more clearly hereinafter. The-piston rod I9 slides with a relatively close t through an aperture 2`I formed in a partition member 28 formed of in,- sulating material and threadedly secured at 29 to the upper end ofthe cylinder I2.

From the above description it will .be apparent that the partition member 28 ,cooperates .with the cylinder I2, piston sleeve I'I and piston member I5 in forming a substantially enclosed pliessure-generating chamber generally .designated by the reference `numeral 30.

Within the substantially enclosed `pressuregenerating chamber 30 is disposed a contact structure generally designated by the reference numeral 3I and in this instance comprising two contacts 32 secured to the piston member ,I5 and movable therewith, being joined at .their lower ends by a conducting bar 33. The contact structure 3I also comprises `a pair of contacts 34 threadedly secured to a conducting ring-shaped member 35 disposed within the pressure-generating chamber 30 and surrounding the pistou rod I9. The contact structure 3I is cooperable to establish a pressure-generating arc within the pressure-generating chamber `3l). By employing two pairs of contacts 32, 34 there results summetry and longer Contact life, since the pressure-generating arc will sometimes be drawn on one pair of contacts 32, 34 and sometimes on the other pair of contacts `32, 34. Also threadedly secured to the conducting ring-shaped member 35, as more clearly shown in Fig. 3, are a pair of conducting bolts 36 having insulating sleeves 31 disposed therearound which slide with a re1- ativcly close iit through apertures 38 provided in the piston member I5. At the `lower end .of the conducting bolts ,36 are secured flexible shunts 39, the other ends of which are electri.- cally connected to `bolts 4U, only one of which is shown in Fig. 1 and acts as a line terminal.

Referring to Fig. 3 it will be observed that compression springs 4i encircle the insulating sleeves 3'I between the ringshaped member 35 and the piston member I5, thereby biasing the contacts 34 upwardly away from the contacts 5 32. However, in the closed circuit position as shown in Fig. 1, a. plurality, in this instance four insulating operating rods `42 extending upwardly `through the partition ,member 28 through an insulating plate 43, joined at their upper ends by a plate 44, and biased downwardly by a compression spring 45, serve to hold the contacts `3,2, 34 in abutting engagement.

An armature member 45 is secured to the plate 44 and slidably moves within the bore 4l of a Vsolenoid 48, which is preferably disposed in series circuit so that the armature 4G is responsive to .overload conditions existing in the series electrical circuit controlled by the interrupter.

Consequently, in the closed circuit position of the interrupter as shown in Fig. l, the electrical circuit .therethrough comprises the terminal stud 49, connector 50, solenoid 48, Vconnector 5I, stationary interrupting contact 52, movable interrupting Contact 22, conducting spider portion 2I flexible conductor 53, conducting rod 54, conducting bar 33, contacts 32, contacts .34, conducting ringeshaped member 35, conducting bolts 3 6, flexible shunts 3,9 to the terminal bolt `4K1.

The stationary and movable interrupting contacts .52, "22 collectively form a i-lrst contact structure cooperable to establish .an interrupting arc, not shown, within a substantially enclosed interrupting chamber generally designated b y the reference numeral 5,6. The upper end of the interrupting chamber 56 is substantially closed by a suitably shaped insulating member 57 forming an orifice 58 and .being `provided with a plurality of iluid conducting lpassages 59 which lead from the region to the oriiice 58.

The movable interrupting contact 22 has a flange 4iii) integrally formed therewith which moves downwardly during the opening operation into an annular recess 6I formed by the insulating member 5l.

y From the foregoing description it will be apparent that the Contact actuating member 23, spider portion 2| and compression spring 62 collectively form a lost-motion mechanical connection generally designated by the reference numeral 63 interconnecting the piston member 1I5 and the movable interrupting contact 22 of the first contact structure 55.

A compression spring 64 seated on the plate 4 biases the piston member I5 upwardly toward its closed circuit position. Stops 65 secured as by 55 Welding to the plate 4 may be provided to stop the downward movement of the piston member The operation of the interrupter will now be explained. During the existence or overload ,conditions in the circuit controlled by the interrupter the solenoid 48 will draw the armature 46 upwardly against the ldownward biasing force of lthe compression spring 45, thereby moving the plate 44 and the operating rods 42 upwardly thus permitting the compression springs 4I to move the ring-shaped member 35 upwardly away from the piston member I5 separating the second con tact structure 3I to establish `a pressure-generating arc Within the pressure-generating chamber 3U. The pressure-generating arc will react upon the oil completely lling the pressure-generating chamber 3U .to form gas which will cause the pressure-generating chamber 3i] to be expanded by causing the downward movement of the piston member I5 against the upward biasing action of the compression spring 64. During the downward movement of the piston member I5, the movable interrupting contact 22 will remain in engagement with the stationary interrupting contact 52 because of the upward biasing action of the compression spring 62 disposed in the bore 28 of the piston rod I8.

Pressure within the pressure-generating chamber 30 will rise to cause continued downward movement of the piston member I5 and piston rod |9, until the piston member I5 approaches the stops 65. When this occurs the contact actuating member 23 will engage the spider portion 2I in abutting engagement to forcibly cause the movable interrupting contact 22 to move downwardly away from the stationary interrupting contact 52, thereby causing a separation of the rst contact structure 55 to draw an interrupting arc within the orifice 58 disposed at the upper end of the substantially enclosed interrupting chamber 56.

Also at this time the grooves or flutes 26 pass below the wall means or partition member 28 to thereby cause an intercommunication between the pressure-generating chamber 39 and the interrupting chamber 56 to permit the gas and oil under pressure to flow upwardly out of the pressure-generating chamber 30 through the ilutes 26 past the wall means 23 upwardly into the interrupting chamber 56 and out of the interrupting chamber 56 adjacent the interrupting arc through the oriiice 58 to thereby cause an extinction of the interrupting arc.

The extinction of the interrupting arc breaks the electrical circuit through the interrupter, thus also causing the extinction of the pressuregenerating arc. Because of the compression springs 64, 82, and 45 the movable parts of the interrupter will gradually move toward their closed circuit positions as shown in Fig. l, the speed of motion depending upon the leakage of oil past the moving parts of the interrupter. Suitable disconnect means disposed in series circuit may be employed or the movable parts of the interrupter may be latched to their full open circuit position.

From the foregoing description it will be apparent that I have provided an improved interrupter which stores the pressure created adjacent the pressure-generating arc until it assumes a value suiiicient to eifectively cause the interruption of the interrupting arc, at which time opening means are actuated through the wall means 26 separating the interrupting chamber from the pressure-generating chamber to thereby permit gas and oil under pressure to flow through the opening means 26 past the wall means 28 into the interrupting chamber 56 to cause an extinction of the interrupting arc.

It will be noted that the volume of the pressure chamber 3|! increases a predetermined amount before drawing the interrupting arc. It is important that the volume of gas generated also be suflicient; otherwise not enough ow for interruption will occur. Both the pressure and volume are controlled in the present invention.

The rate of reclosure of the movable parts of the interrupter may be regulated by providing the proper size of vent holes 28a between chamber 38 and the other parts of the breaker. The breaker may be provided with suitable lockout mechanism to hold it open after a single or a pre-determined number of operations.

An overpressure safety device is included in that the pressure within the pressure-generating chamber 30 tends to reclose the second contact structure 3| against the bias oi the two compression springs 4| by expelling the bolts 36 and sleeves 31 out of the pressure chamber 30. Thus, if too sudden a Ipressure is generated in the pressure-generating chamber 30, contacts 34 will reclose against contact 32 so that the pressuregenerating source temporarily disappears. Then as soon as piston I5 moves downwardly and thereby relieves the pressure, contacts 34 will again raise to again open the second contact structure to supply the pressure as needed because of the opening bias of compression springs 4|. It is evident, that contacts 34 can be made to reclose at any desired overpressure since they will close when the chamber pressure within pressure-generating chamber 30 times the crosssectional area of sleeves 31 and bolts 36 exceeds the force of springs 4 I.

From the foregoing it is apparent that I have Iprovided novel means for shortening the length of the pressure-generating arc upon the attainment of excessive pressure within the pressuregenerating chamber 38.

In the embodiment of my invention shown in Figs. 5 and 6 an arrangement is shown whereby the novel interrupting structure which I disclose may be used in a conventional tank in which may be operated the conventional movable conducting bridging member actuated by the vertical insulating operating rod. More speciiically, referring to Fig. 5 the reference numeral 68 designates a tank filled to the level 69 with a suitable arc extinguishing i'luid 10 in this instance circuit breaker oil. Depending from the cover 1| of the tank 68 are two insulating bushings 12 13, through which terminal studs 14, -I5 extend.

Threadedly secured to the lower ends of the terminal studs 14, 15 are contact feet 16, 11 which rigidly support in position two identical arc extinguishing units generally designated by the reference numeral 18. A conducting bridging member 19 actuated reciprocally in a vertical direction by an insulating operating rod 88 electricallyT interconnects in the closed circuit position, as shown in Fig. 5, the two arc extinguishing units 18.

Referring more particularly to Fig. 6 which shows in vertical section the left-hand arc extinguishing unit 18 of Fig. 5, it will be observed that the arc extinguishing structure is the same as was previously described in connection with Figs. 1-4. However, the contact foot 16 is threadedly secured at 8| to the upper end of the metallic cylinder I2.

The lower end of the insulating casing 1 is closed by a conducting plate 82 rigidly secured in place by bolts 83. The stationary interrupting contact 52 is threadedly secured at 84 to the conducting plate 82. Stationary disconnect contacts 85 are provided externally of the plate 82 being rigidly secured thereto by bolts 86. A movable disconnect contact 81 biased upwardly by a compression spring 88 makes engagement in the closed circuit position as shown in Fig. 5 with the stationary disconnect contacts 85. The lower end of the movable disconnect contact 81 is electrically connected by a conductor 89 to the conducting bridging member 19 by a. bolt 90.

The compression spring 88 is disposed within a metallic housing cylinder 9| forced by a pressed lt into an aperture 92 provided at the extremity of the bridging member 19. A compression spring 93 encircles the housing 9| and biases upwardly a. cup-shaped member 94, the upperend of which engages yin abutting 1relatirm :a rineshaped `metallic plate 195 to which the insulating operating rods 42 are Athreadedly secured at 9B.

The upward movement of the cup-shaped member `94 is determined by a flange portion 91 integrally formed with the housing V3| Consequently, in this embodiment of my invention it is apparent that in place of the electromagnetic device 48 which was used in F-ig. l, a mechanically actuated device, generally desigated b y the reference numeral 98 is employed to effect initial downward movement of the operating rods 42 as determined by downward movement of the insulating operating rod 80. A compression spring 9.9 biases the operating rods 42 secured to the ring-shaped plate 95 downwardly.

Consequently, from -the vforegoing description it is apparent that to open the electrical circuit passing through the interruptor `shown in Figs. 5 and ,6, the operating rod 8l) is moved downwardly by suitable means, not shown. This causes downward movement of the conducting bridging member 19 which permits the compression spring 99 to force the operating rods Y42 downwardly. This establishes a pressure-generating arc liil within the pressure-generating chamber 30 as shown in Fig. 6. Following a predetermined upward travel of the linsulating piston member I5 the contact actuating member 23 engages the spider portion 2| to cause -upward movement of the movable interrupting contact 22 to thereby cause an interrupting are ,lOl to be drawn within the orifice 58. The iutes 26 rpassing through the wall means 28 permit oil and gas under pressure to pass from the pressure-generating chamber 30 through the flutes 26 into the interrupting chamber 56 adjacent the arc I0| within the oriflee 58 and `out the exhaust ports |02 disposed in the insulating casing 1. During this time 4the movable disconnect contact 81 remains in en- .A

gagement with the stationary disconnect contact 85 so that the interrupting of lthe circuit takes place within the .arc extinguishing .unit 18 and not exteriorlly thereof at the contacts 85, :81. However, following interruption of the circuit .the movable disconnect contact 81 separates Afrom the stationary disconnect contact 85 to introduce an isolating gap into the circuit vas .shown more clearly by the dotted lines |03 ,in Fig. 5.

From the foregoing description it is apparent that my invention `is readily Aadapted to a circuit breaker construction in which two .arc yextinguishing units are disposed -withi-n a tank Vstructure .and lare electrically interconnected by a conducting bridging member vertically ,actuated by an insulating operating rod 80.

In the embodiment of my invention shown in Figs. 7 and 8, I provide means for utilizing pressure generated at the pressure-.generating arc Ato establish superimposed pressure adjacent the interrupting contact structure prior to the .opening of the interrupting contact structure. Subscquently, I employ a higher pressure generated at the pressure-generating arc for effecting fluid flow toward the interrupting arc when Athe latter is established in a medium of superimposed pressure.

More specifically, referring particularly to Fig. 7, the reference numeral |106 designates a tank structure having .a partition member |31 provided intermediate its ends. Fluid |08, in this instance circuit breaker oil, lls the tank |05 to the level |09, one or more vent holes Il) vbeing provided to permit a lling of the substantially enclosed Apressure-generating chamber 30 disposed Ain the Ilower portion -of the tank structure |06. 'The :first contact .structure 55 in this 'instance comprises a pai-r of hollow/.contacts Il, I2, the nrst of -whicn is Arig-idly secu-red toa metallic plate H3, and the second oi -which is vmovable and secured to a conducting contact vrod H4 having a Iiange ||5 integrally formed therewith.

The second contact structure, in this instance comprises a hollowfstationary contact H6 having a Lconducting tubular extension H1, Ethe upper end of which communicates with the interrupting chamber 56 by suitable conduit means in this instance assuming the form vof a pipe H8. Valve means generally designated by the reference numeral l t9 closes the conduit means |I8 upon a predetermined pressure ,within the interrupting chamber 55 -as determined bythe piston |23 and compression spring |,2.|. An `overpressure Valve Ir2'2 may be provided in an insulating cap |23 closing the upper .end `oi? the interrupting chamber E56 which is formed by an insulating cylinder |24.

'The movable pressure-generating contact |25 is actuated in a reciprocal vertical direction by an insulating operating rod |26 latched upwardly in its .closed `circuit :position by ya latching device generally designated Lby the reference numeral 21 a-ndcomprlsing an armature |28 associated with asolenoid |29.

n. compression spring |30 is disposed between a cap itl and a iiange |32 integrally formed with the insulating operating rod |26, thereby biasing the movable pressure-generating contact |25 downwardly towards its open circuit position.

From the foregoing description it is apparent that in the closed circuit position of the interruptor as shown in Fig. 7, the `electrical circuit therethrough comprises terminal stud |33 extending through bushing |34,-connector |35, lbolt |36, connector |31, movable pressure-generating contact |25, stationary pressure-generating contact H3, tubular extension H1, conducting conduit H3, conducting cup-shaped member |38, flexible strap 13.*., 4conducting plate |-|3, stationary interrupting contact movable interrupting contact 4l 2, conducting contact rod I4, ilexible strap |49 to terminal bolt |4| to which a terminal lug |62 may ybe rigidly secured.

To `open the 'electrical' circuit passing through the interrupter the latching device |21 is actuated either manually or in response to overload conditions existing in the circuit controlled by the interruptor to permit the compression spring |30 to torce the insulating operating rod |28 downwardly `so that the 4movable pressure-generating contact l2 5 engages the stop |43 integrally formed with rthe insulating cup-shaped member |44. This establishes a pressure-generating arc, not shown, within the pressure-generating chamber .which reacts upon the oil disposed therein to create gaseous pressure. `This gas under pressure acts upwardly through the guide spider |45, upwardly through the tubular extension l1, cond-uit H8 and into the interrupting chamber y56. When the interrupting chamber 56 has attained a predetermined superimposed static gaseous pressure, the piston |23 will be moved toward the left against lthe biasing action of the compression spring 12| to cause the valve means I9 to close the cond-uit means ||8.

Meanwhile, the pressure-generating arc continues to raise the pressure within the pressuregenerating chamber 39 and thereby causes the same to expand by upward movement of the piston 4|46 moving upwardly Within the piston cylinder |421, the lower end of which is threadedly secured at |48 to the partition member |01. The upward movement of the piston |46 takes place in opposition to the compression spring |49 disposed in the upper portion of the piston cylinder |41. The piston |46 has rigidly secured thereto a piston rod |50 having a pin |5| passing therethrough at its lower end. Following a predetermined upward movement of the piston |46, the pin engages the bifurcated portion |52 of -a lever |53 pivotally mounted intermediate its ends at |54 to a bracket |55 which may be secured in any suitable manner, as by welding, to the lower metallic plate |56 of the tank structure |06.

The left-hand end of the lever |53 has a slot |51 formed therein through which extends a pin |58 secured to and movable with the contact rod ||4.

Consequently, upon a predetermined upward movement of the piston |46 in response to a predetermined pressure rise within the pressure generating chamber 30 the contact rod ||4 will be forcibly moved downwardly to thereby separate the rst contact structure 55 thereby establishing an interrupting arc between the cooperable contacts ||2. Practically simultaneously with the separation of the first contact structure 55 the ange l5 secured to the contact rod |4 opens the valve |59 which closes an aperture |60 provided through the lower end of the casing |24 to thereby permit intercommunication between the pressure-generating chamber 30 and the interrupting chamber 56.

When this occurs uid under pressure will pass from the pressure-generating chamber 30 through the aperture |60 through a plurality of tubes |6| composed of insulating material and radially inwardly between the separating contacts l, ||2. After contacting the interrupting arc this fluid will exhaust either upwardly through the hollow stationary interrupting contact or downwardly through the hollow movable interrupting contact ||2 out ports |62 into region |63 upwardly through insulating tubes |64 to the region |65.

The result is a rapid extinction of the interrupting arc drawn between the contacts ||2 in a region of superimposed pressure.

From the foregoing description it will be apparent that in this embodiment of my invention I separate the second contact structure first, thereby forming a pressure-generating arc, the pressure established adjacent to it being iirst utilized to create a superimposed pressure within the interrupting chamber 56. Subsequently, a higher pressure generated within the pressuregenerating chamber 30 causes the opening of the first contact structure drawing an interrupting arc and effecting the extinction thereof by a flow of fluid passing from the pressure-generating chamber 30 intothe interrupting chamber 56 under a higher pressure than that initially used in establishing the superimposed pressure within the interrupting chamber 56. The dash-pot |61 10 is employed to temporarily maintain the rst contact structure open. Disconnect means disposed externally of the tank structure |06 may be employed to effect an isolating gap in the circuit, or the movable parts may be latched in their open circuit position.

When it is desired to close the circuit passing through the interrupter, suitable means, not shown, may be employed to eiect upward movement of the insulating operating rod |26 to effect a closure between the contacts ||6, |25 and permitting a latching of the latching device |21 to take place.

It will be observed that upon the attainment of excessive pressure within the pressure-generating chamber 30 that this pressure will act upon the projected area of the insulating operating rod |26 to force the latter upwardly against the downward biasing action of the compression spring |30, thereby shortening the length of the pressure-generating arc. Thus, in this embodiment of my invention I have again provided means for shortening the length of the pressuregenerating arc upon the attainment of excessive pressure within the pressure-generating chamber 30.

The device shown in Fig. '7 illustrates an arrangement by means of which the pressure-generating are builds up a superimposed pressure of some definite value, but smaller than the pressure in the pressure chamber 30 before the main contacts ||2 open. A pressure release valve |22 is also employed in conjunction with the interrupting chamber 56.

From the foregoing description it is apparent that I have provided an improved interrupter in which the pressure formed in the pressure generating chamber 30 will cause a reclosure of the pressure-generating contacts ||6, |25 when the force on the projected area of the insulating operating rod |26 exceeds the downward force exerted by the compression spring |30. Thus, the pressure is controlled within the pressure generating chamber 30.

The above disclosure indicates how my invention may be applied to circuit interrupters of widely diierent types. Although my invention has been disclosed using oil as the interrupting medium, it is apparent that gas could be employed. I have shown how superimposed pressure may be created within the interrupting chamber by utilizing a portion of the pressure generated at the pressure-generating arc. Subsequently, a higher pressure may be employed to drive uid from the pressure-generating arc toward the interrupting arc to eiectively quench the latter.

Although I have shown and described several specific structures, it is to be clearly understood that the same were merely for the purpose of illustration and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. In a circuit interrupter, means dening a substantially enclosed interrupting chamber within which an interrupting arc is established, means defining a substantially enclosed pressuregenerating chamber within which a pressuregenerating arc is established, conduit means interconnecting the two chambers, valve means disposed in the conduit means closing the same upon a predetermined rise of pressure within the interrupting chamber, and means establishing 11 intercommunicationbetween the tivo chambers `at a predetermined `pressure within the pressuregenerating chamber which is higher in magnitude than the pressure necessary to close the valve. means in the conduit means.

2. In a circuit interrupter, means dening a Substantially enclosed interrupting chamber within which. an interrupting arc is established, means dening a substantially enclosed pressuregenerating chamber Within which a pressuregenerating arc is established, conduit meansy interconnecting the. two chambers, valve means disposed in the conduit means closing the same upon. a predetermined rise of pressure within the interrupting. chamber, means permitting an intercommunication between the two chambers at a` predetermined pressure' Within the pressuregenerating chamber which is higher in magnitude than the pressure necessary to close the valve means in the conduit means, and means for shortening the lengthv of the pressure-generating arc upon the attainment of excessive pressure within the pressure-generating chamber.

3. In a circuitl interruptor, a iirst contact structure to draw an interrupting arc, a second contact structure to draw a pressure-generating arc', a. piston member, a substantially enclosed pressure-generating.chamber Within which the pre-ssure-generating, arc is established and having one wall thereof formed by the piston member, the piston member being responsive to the pressure within` the pressure-generating chamber, and a lost-motion. mechanical connection interconnecting the piston member and theirst contact structure to. cause theactuation of thesame.

4. In a circuit interrupter,` a partition member, means deining adjacently disposed interrupting and pressure-generating chambers separated by a partition member, a piston member having a pistonV one Wall of the pressure-generating chamber beingI formed by the piston4 member, and theI piston rod being. slidable through. the partition member.

5'. In a circuit interrupter, a partition member, means defining adjacently disposed interrupting and pressure-generating. chambers separated by the partition member, a piston. member having a piston rod, one wallof the pressure-generating chamber being, formed by the. piston member, the piston rod being slidable through the partition member, first contact structure `disposed in the interrupting chamber to draw an interrupting arc, and a. lost-motion mechanical connection interconnecting the piston rod and the rst contact structure to cause the actuation of the same.

6'. In a circuit interrupter, a partition member..

ing a contact Secured to and movable with. thev piston member.

7. In a circuit interrupter, a partition member, means defining` adiacently disposed interrupting.

Aand pressure-generating chambers separated by the partition member, a piston member having a piston rodi, one Wall of the pressure-generating chamber being formed by the piston member, the piston rod. being. slidabie through the partition member, rst contact structure disposed in the interrupting chamber to draw an interrupting arc, a lost-motion mechanical connection interconnecting the piston rod and the rst contact structure to cause the actuation of the same, a secon-dcentact structure disposed Within the pressure-generating chamber cooperable to establish a pressure-generating arc and` comprising a contact secured to and movable with the piston mem- .iber a ring-shaped conducting member disposed Within the pressure-generating chamber and surrounding the piston rod, the second contact `structure also comprising a contact secured to thel ring-shaped conducting member.

83,. In a circuit in-terrupter, a partition member, `means derining acl-jacently disposed interrupting and. pressure-generating chambers separated by the partition member, a piston member having apiston red, one Wally of the pressure-generating chamber being formed by the piston member, the piston rod-v being slidable through the partition member, first Contact structurev disposedY in theinterrupting chamber to draw an interrupting are, a lest-motion mechanical connection interconnecting the piston rod and the iirst Contact structure to cause the actuation of the same, a second contact structure disposed Within the pressure-generating chamber cooperable to establish. a. pressure-generating arc and comprising a contact secured to and movable with the piston member, a ring-shaped conducting member disposed Within the pressure-generating chamber and surrounding theA piston rod, the second contact.V structure also comprising a contact secured to the ring-shaped. conducting member, means biasing,- the. ring-shaped conducting member away from. the piston member, and means comprising one or more operating rods for maintainingT the second contact structure in abutting engagecnt in. the closed` circuit position.v

9'. In. a circuitinterrupter, a partition member, means dening. adjacently disposed interruptingr andrand. pressure-generating chambers separated by the partition member, a piston` member having aY pistony rod,v one wall oi the pressure-generating. chamber being formed by the piston member, the piston rod being slidable 'through the. partitionr member, rst contact structure disposed in. the interrupting. chamber to draw an interrupting. are, a. lost-motion mechanical connection interconnecting, the piston rodV and. the rst Contact structure to cause the actuation of the Same, ai second Contact structure disposed within the pressure-generatingchamber cooperable to establish a pressure-generating arc and'` comprising a Contact secured to and movable with the piston member, a ring-shaped conducting, member disposed within thev pressure-generating. chamber and surrounding the piston rod, thel second` contact structure also comprisingf a ContactV secured'. to the ring-shaped conducting member, the ring-shaped member having a portion: extending through the piston member.

110. In' acircuit interrupter, a partition member,. means defining adjacently disposed interrupting and pressure-generating chambers separated by the partition member, a piston member having. a piston rod', one wa-ll of the pressuregenerating chamber being formed by the piston i memben. the piston rod being., slidable through the partition member, iirst contact structure disposed in the interrupting chamber to draw an interrupting arc, a lost-motion mechanical connection interconnecting the piston rod and the first contact structure to cause the actuation of the same, a second contact structure disposed within the pressure-generating chamber cooperable to establish a pressure-generating arc and comprising a contact secured to and movable with the piston member, a ring-shaped conducting member disposed within the pressure-generating chamber and surrounding the piston rod, the second contact structure also comprising a contact secured to the ring-shaped conducting member, means biasing the ring-shaped conducting member away from the piston member, and means comprising one or more operating rods for maintaining the second contact structure in abutting engagement in the closed circuit position, the ring-shaped member having a portion extending through the piston member.

11. In a circuit interrupter, a partition member, means dening adjacently disposed interrupting and pressure-generating chambers separated by the partition member, a piston member having a piston rod, one wall of the pressuregenerating chamber being formed by the piston member, the piston rod being slidable through the partition member, and the piston rod having one or more flutes formed therein to permit intercommunication between the two chambers after a predetermined opening movement of the piston member.

12. In a circuit interrupter, an operating rod, an electromagnetic device for raising the opera*- ing rod upon predetermined overload conditions, means defining adjacently disposed interrupting and pressure-generating chambers, a partition member separating the two chambers, a piston member having a fluted piston rod forming the lower wall of the pressure-generating chamber, the piston rod passing slidably through the partition member, first contact structure disposed within the interrupting chamber and cooperable to establish an interrupting arc, a lost-motion mechanical connection, the rst contact structure being interconnected by the lost-motion mechanical connection to the piston member, a ring-shaped member disposed within the pressure-generating chamber and surrounding the piston rod, second contact structure disposed within the pressure-generating chamber cooperable to establish a pressure-generating arc therein and comprising a contact secured to and movable with the piston member and a contact secured to the ring-shaped member, a conducting portion of the ring-shaped member extending through the piston member, means biasing the ring-shaped member upward away from the piston member, and means biasing the operating rod downward to hold the contact secured to the ringshaped member in abutting engagement with the contact secured to the piston member.

13. In a circuit interrupter, an arc extinguishing unit, an operating rod extending through the lower wall of the unit, a pressure-generating chamber disposed adjacent the upper end of the unit` an interrupting chamber disposed adjacent the lower end of the unit, a conducting bridging member for actuating the operating rod, a piston member forming the upper wall of the pressuregenerating chamber and having a fluted piston rod secured thereto, a partition member separating the two chambers, the piston rod passing slidably through the partition member, rst contact structure-disposed in the interrupting chamber, a lost-motion mechanical connection, the

"rst contact structure being connected by the lost-motion mechanical connection to the piston member, a second contact structure disposed within the pressure-generating chamber and comprising a contact secured to and movable with the piston member, a ring-shaped member carrying a contact, the operating rod forcing the contact secured to the ring-shaped member against the contact secured to the piston in the closed circuit position of the interrupter.

14. A circuit interrupter including means comprising a piston for defining a substantially enclosed pressure-generating chamber, means for establishing a pressure-generating arc within the pressure-generating chamber, means defining an adjacently disposed interrupting chamber, means for establishing an interrupting arc within the interrupting chamber, wall means separating the two chambers, opening means for the wall means including the piston which forms one wall of the pressure-generating chamber and is movable in response to increase of pressure therein to thereby appreciably increase the volume thereof, the opening means establishing intercommunication between the two chambers upon a predetermined rise of pressure within the pressure-generating chamber, and means operatively connecting the piston with the means for establishing the interrupting arc.

l5. In a circuit interrupter of the liquid-break type, a rst contact structure to draw an interrupting arc within liquid, a second contact structure to draw a pressure-generating arc within liquid, a piston member, a substantially enclosed pressure-generating chamber containing liquid within which the pressure-generating arc is established and having one wall thereof formed by the piston member, the piston member being responsive to the pressure within the pressure-generating chamber, and a lost-motion mechanical connection interconnecting the piston member and the first contact structure to cause the actuation of the same.

16. In a circuit interrupter, a rst contact structure operable to draw an interrupting arc within an interrupting chamber, a second contact structure to draw a pressure-generating arc, a piston member, a substantially enclosed pressure-generating chamber within which the pressure-generating arc is established and having one wall thereof formed by the piston member, the piston member being responsive to the pressure within the pressure-generating chamber, means causing intercommunication between the pressure-generating chamber and the interrupting chamber, and a lost-motion mechanical connection interconnecting the piston member and the rst contact structure to cause the actuation of the same.

1'7. In a circuit interrupter, means dening an interrupting chamber, a iirst contact structure to draw an interrupting arc within the interrupting chamber, a second contact structure to draw a pressure-generating arc, a piston member, a substantially enclosed pressure-generating chamber within which the pressure-generating arc is established and having one wall thereof formed by the piston member, the piston member being responsive to the pressure within the pressuregenerating chamber, means establishing intercommunication between the pressure-generating chamber and the interrupting chamber following the attainment of a predetermined pressure ammo within the pressure-generating chairmen and a lost-motion` mechanical' connection interconnecting the piston member' andthe first contact structure to cause the actuation ofA thesame.

18. In a circuit interrupter, means denning an interrupting. chamber, a rst contact structure to= draw an: interrupting' arci withinl the' interrupting chamber, a second Contact structure toi draw a `pressure-generating arc, a piston member, a substantially enclosed pressure-generating chamber within which the' pressure-generating arc is established and having one' wall thereof formed vby the piston: member, the piston member being responsive' to the pressure withinI thepressuregenerating chamber, conduit means interconnecting the two chambers, valve' means disposed in the conduit means closing the same upon a pre'- determined rise of pressure' within the interruptirig chamber, means establishing intercommunication betweenJ the tw'o chambersl at a predetermined pressure within the pressure-generating chamber which is higher inV magnitude than the pressure necessary to close-the valve means in the conduit means,y and: a lost-motion mechanical connection interconnecting the piston member and the first contact structure to cause the actuation of the same.

1'9; A circuit interrupter of the liquid-break type including mea-nscomprising a piston for dei-"ming a substantially enclosed pressure-generating chamber containing liquid, means for establishing a pressure-generating arc within the pressure-generating chamber', means dening an adjacently disposed interrupting chamber containing liquid, means for establishing an interrupting arcv within'. the liquid disposed Within the interrupting chamber, wall means separating the two chambers, opening means for the wall means including the piston which forms one wall of the pressure-generating chamber and is movable in response to increase'of pressure therein to thereby appreciably increase the volume thereof, the opening means establishing in-tercemmunication between the two' chambersv upon a predetermined rise of pressure within the pressure-generating chamber,` and meansv operatively connecting the pistonA with the means for establishing the interrupting arc.

20.r A circuit in-terrupter includ-ing means comprising. a piston for dening a substantially enclosed pressure-generating chamber, means for establishinga pressure-generating arc Within the pressure-generating chamber, means defining an adjacently disposedlinterruptingcham-ber, means for' establishing an@ interrupting arc within the interrupting chamber, wall means separating the two chambers-openingmeans-for the wall means including the pistonwhich forms one wall of` the pressure-generatingi chamber and is. movable in response to increase of pressure therein to thereby `appreciably increase' the volume thereof, the opening means establishing intercommunication betweenl the twochambers upon a predetermined rise of pressure Within the pressure-generating chamber, and means operatively connecting the Vpiston by a lost-motion mechanical connection with the means for' establishing the interrupting arc.

21. A circuit interrupterincluding means comprising a piston for denin'g a substantially enclosed pressure-generating chamber, means for establishing a pressure-generating arc within the pressure-generating chamber, meansl defining an adjacently disposed interrupting chamber, means for establishing anv interrupting arc within the interrupting chamber, conduit means interconnecting the two chambers, valve means disposed in the conduit means closing the same upon a predetermined rise of pressure within the interrupting chamber, wall means-separating the two chambers, openingv means for the wall means including the piston which forms one wall of the pressure-generating chamber and is movable in response to increase of pressuretherein to thereby appreciably increase the volume thereof, the opening means establishing intercommunication between the two chambers upon a predetermined rise of pressurev within the pressure-generating chamber,l and means operatively connecting the piston with the means for establishing the interrupting arc.

ALBERT P. STROM.

REFERENCES CITED' The following references are of record in the file of this patent:

UNITED STATES PATENTS r112,824 France Aug. 3, 1931