US2419446A

US2419446A - Electric circuit breaker

Info

Publication number: US2419446A
Authority: US
Publication date: 1947-04-22
Anticipated expiration: 1964-04-22

Description

April/22, 1947- c. H. FLURscHElM 2,419,446

I ELECTRIC CIRCUIT BREAKER Filed July 18, 1944- 5 Sheets-Sheet 1' Inventor: Cedric Harold Flurschem,

b 1M MMA, y His Attorney.

April 22, 1947. c. H. FLURscHElM 2,419,446

ELECTRIC CIRCUIT BEAKER Filed July 18, 1944 5 Sheets-Sheet 2 inventor z Cech"c Harold Flurscheim,

His Attorney.

April 22, 1947. c. H. FLURscHElM 2,419,446

ELECTRIC C1RCUIT BBEAKER Filed July 1:2, 1944 5 Sheets-Sheet 5 Invervtcpr* Cedric Harold Flurschem,

l/MQVMJ im O t www w April 22, 1947- c. H. FLURSCHEIM 2,419,446

ELECTRIC CIRCUIT BBEAKER Filed July 1s, 1944 5 sheets-sheet 4 In Veni-,o1` lCedric: Harold Flurschem,

by f JM HIS Attorney.

April 22, 1947. c. H. FLURSCHEIM 2,419,446

ELECTRIC CIRCUIT BREAKER Filed July 18, 1944 5 Sheets-Sheet 5 Patented Apr. 22, 1947 UNITED STATES ELECTRIC CIRCUIT BREAKER Cedric Harold Flurscheim, Bowdon, England, assignor to Metropolitan-Vickers Electrical Company Limited, a British company Application July 18, 1944, Serial No. 545,440 In Great Britain July 28, 1943 9 Claims.

This invention relates to air or gas blast electric switches or circuit breakers of the kind in which cooperating contacts mounted within a contact or arcing chamber are adapted to be separated by the application of pressure to said 5 chamber which is provided with one or more discharge openings or the equivalent so that said pressure will cause a blast of air or gas past the contacts thereby to extinguish the arc drawn upon interruption of the circuit through said contacts.

In a well-known form of such switches the arcu ing or contact chamber above referred to comprises a tubular member of insulating material Within which the contacts are mounted for relative movement parallel with the axis of said tubular member, the air or gas for producing the blast being caused to flow axially through said tubular member and past a nozzle therein which may be formed by one of the contacts or by a separate member such as of insulating material. Such arrangements, however, suffer from the dis advantage that the contacts and particularly the moving contact displaceable by the pressure within the arcing chamber are not readily accessible.

The present invention has for its object to provide an improved arrangement of arcing or contact chamber and contacts which Whilst applicable in a single-break switch is well adapted where desired for application in series with one or more similar units to provide a multibreak switch. The invention also provides according to another aspect, such arrangements whereby improved accessiblity of the contacts and particularly of a contact or contacts displaceable by `the gas pressure is obtained.

In order that the invention may be more clearly understood reference will now be made by way of example to the accompanying diagrammatic drawings, in which Fig. 1 is an elevation mainly in section of a preferred contact arrangement according to the invention,

Figs. 2, 3, 4 and 5 show by way of example several applications of the arrangement according 45 to Fig. 1, Fig. 4 being a plan View of the arrangement shown in Fig. 3,

Fig. 6 shows partly in cross-sectional eleval tion to an enlarged scale an arrangement corresponding with Fig. 5 and incorporating a fur- 50 ther feature of the invention,

Fig. "I is an elevation of a further multi-break switch employing a plurality of contact arrangements according to Fig. 1, and

Fig. r8 is an elevationmainlyin cross-section 55 2 showing a modification of the arrangement` of Fig. 1.

Similar parts in the several gures are denoted by like reference numerals.

Referring iirst to Fig. 1, the contact arrangement is formed as a unit comprising a fixed main contact I and a co-operating movable contact 2, mounted within a metal Contact chamber 3. The contact I comprises a tubular member extending through, and located in a side wall of the chamber 3 by, an insulating bushing 4, which may be of porcelain for example or may be a condenser type bushing. This bushing is retained in place by a ring 4a bolted to a flange on a cylindrical portion 5 of the chamber 3. The contact member I is retained in place axially within the bushing by means of a ange Ia and an end plate Ib screwed on to the end of the said member, the ange la and plate Ib abutting against the ends of the bushing 4. The moving contact 2, which is also of the tubular form, extends through a cylinder 6 projecting laterally from the side wall of the contact chamber 3 opposite to the bushing 4, said moving contact 2 carrying a piston portion 2a. By means of sliding engagement of the right-hand end of the contact member 2 in a cover plate 'l for the cylinder 6, the contact 2 is guided for longitudinal movement toward and away from the (zo-operating fixed contact I, the contacts being shown in the circuit-closed position. The moving contact 2 is connected electrically with the cylinder 6 and thereby With the contact chamber as a whole by means of an annular resilient contact construction 8 with which the contact has sliding engagement, This resilient contact construction may be of any of the well known forms. The contact 2 is biased into engagement with the contact I by means of a helical compression spring 9 surrounding the contact 2 and abutting at its ends respectively against the contact construction 8 and the pisf ton 2a.

The contact chamber 3 is in the arrangement shown in Fig. l mounted upon a tubular insulator pillar, the upper end of which appears at I, and is provided with a central aperture II in which is registered the upper end of an insulating air supply conduit I2. The conduit I2 is connected at its lower end (not shown) through a suitable control valve with a, reservoir or other source of air (or gas under pressure, the conduit being thereby adapted to supply air or gas under pressure to the contact chamber 3 during the circuit-interrupting operation, which air or gas pressure will displace the piston 2a and thereby the moving contact 2 toward the right in the drawing so as to separate the contacts. The air or gas pressure within the contact chamber S will then result in flow or" air or gas radially through the gap between the contacts and axially through the passages within the tubular contacts i and E so as to extinguish the arc in well known manner, the air or gas of the blast and the arc gases being discharged to atmosphere from the outer ends of said contacts. if desired suitable means indicated diagrammatically at E3 and I4 may be provided for cooling said gases in otherwise known manner.

The cover plate 'I is secured to a flange l provided on the cylinder' 8 by means of bolts lwhereby said cover plate may readily be removed from the cylinder so as to allow withdrawal ol the contact construction 8, spring' piston 2a.

and contact 2 from the arcing chamber when inspection of, or attention to, the contacts is required, this withdrawal of the contact being facilitated by the arrangement in which the air supply conduit l2 is disposed perpendicularly to the direction in which said contact is withdrawn from the contact chamber. It will be seen that when the parts above referred to have been withdrawn from the cylinder 5 access may readily be obtained through the cylinder E to the contact face o the xed contact i.

t will be understood that the unit shown in Fig. l may be arranged in any desired manner in a switch or circuit breaker. One example is shown in Fig. 2, this circuit breaker comprising a double-break switch consisting oi two units A and B each constructed in accordance with Fig. i and mounted on a suitable foundation 23 by means of the tubular insulating pillars designated il) in Fig. l and designated 3A and ISB respectively in Fig. 2. The contact chambers 3 of the two units are mounted on the pillars IdA. and I DB so that the two insulating bushings d extend outwardly away from one another whilst the contact chambers of the two units carry fed contacts 22A and 2IB adapted to be connected together by a movable bridging bar 22 which is ixedly mounted at its centre on a rotatable insulating pillar 23 mounted on the foundation 2G in a rotatable manner and adapted to be rotated about its vertical axis by suitable operating means as part of the circuit-breaking operation. ln the illustrated position of the bar the latter engages at its two ends with the contacts ZIA and ZIB respectively. rlhe two conductors 33 and to be connected by the switch are connected with the end plates Ib of the units A and B, respectively, so that the circuit will proceed in series through two pairs of circuit-interrupting contacts, that is to say through the units A and B, and the bridging bar 22. The operating mechanism for the bridging bar 22 is arranged as is otherwise well known in the art so that movement of said bar is co-ordinated with the application of air or gas pressure to the contact chambers 3 to provide isolation by disengagement of said bar from the contacts RIA and IBIB as part of the circuit-opening operation either simultaneously with or after the separation of the arc interrupting contacts I and 2 in each of the units A and B and extinction of the arc between said contacts whereby, upon removal of the air or gas pressure from said unit and consequent reclosure of the arc interrupting contacts I and 2, the circuit will remain interrupted by the bridging bar 22.

Figs. 3 and 4 show, also by way oi example,

another form of double-break switch in which, in place of the central insulating pillar 23 and bridging bar 22, the isolating movement above referred to is obtained by bodily movement of the arc interrupting units with respect to one another. For this purpose in the arrangement oi 3 the contact chambers 3 are mounted on the pillars iii-A and IGB so that the insulating bushings fa extend toward one another and, in the closed position of the switch, in line with one another, the insulating pillars IGA and ICB are arranged` to be rotated in opposite directions to one another by suitable operating mechanism. The unit B is provided with a Contact blade 3S carried by the plate Ib of that unit so as to in electrical connection with the fixed contact l of said unit, whilst the unit A is provided with a co-operating jaw contact 3l carried by the plate lb ci the unit [i and thereby in contact with the ixed contact I of the unit A. rThe two contact chambers 3 carry respective connecting members 533A and 52B mounted on the tops of the respective contact chambers 3 in a manner permitting relative rotational movement between said members and contact chambers about the vertical axis or" the insulating pillars IGA and ISB respectively. These membe s 32A and 32B are connected with the two

conductors

33 and 34,

The switch is illustrated in Figs. 3 and 4 in the circuit-closed position. The isolating movement is obtained by the rotational movement of the insulating pillars IIIA and ISB and the switch units i?. B to the positions indicated at A and B in Fig. 4, the isolating movement being obtained by separation of the contacts 3D and 3|.

it will be understood that the desired isolating operation for maintaining the circuit open after reclosure of the arc-interrupting contacts within the arcing chamber or chambers in singleand multi-break switches may be obtained by any other desired arrangement such as, for example, by means of a separate air-break switch as is also otherv-.f'ise well known in the art. One arrangement of this kind appears in Fig, 5, which shows, as will now be described, an alternative application of arc-interrupting contact units according to Eig. l to provide a multi-break switch.

In the arrangement shown in Fig. 5 two arcinterrupting contact units A and B are mounted one above the other, the contact chamber 3 of the unit A being mounted on the upper end of the insulating pillar` I 0 as in Fig. 1 whilst the Contact chamber 3 of the unit B is mounted upon and spaced with respect to the Contact chamber 3 of the unit A by means of an insulating pillar du. rihe insulating bushings 4 of the two units extend in the same direction from the vertical axis of the insulating pillars I0 and 40 and with their axes conveniently in the same vertical plane as is shown in the figure. The end plate Ib of the unit A is connected by means of a conductor iii with the contact chamber 3 of the unit B whilst the member ib of said unit B is connected with the conductor 33. The Contact chamber 3 of the unit A is connected with the other conductor in general through contact means providing the isolating movement above referred t0. which isolating movement is provided in the arrangement shown by way of example in Fig. 5, by means of a separate isolating switch comprising a conducting blade 42 pivotally mounted at its right-hand end upon the upper end of an insulating pillar partially shown at 43 and engaging at its left-hand end with a contact member 44 carried by the contact chamber 3 of the unit A. This conducting blade 42 is adapted to be disengaged from the contact 44 by a clockwise movement to the position shown at 42 by operating means actuated through a rotatable insulating pillar 45, such arrangements being otherwise well known in the art.

It Will be understood that further arc-interrupting contact units may be mounted above the unit B according to the number of breaks required for arc interruption in any particular application of the arrangement including those shown in Figs. 2, 3 and 4. One such modification provides a further unit C which is indicated in broken lines in Fig. 5, the additional unit C being supported on the unit B by a tubular insulator 4D with the plate Ib of the unit B connected by conductor 4| with the contact chamber 3 of said unit C and the plate |b of said unit C connected with the conductor 33.

In another modification of the arrangement shown in Fig. the several units are mounted one above the other with the insulating bushings 4 thereof extending in diametrically opposite directions to one another from the vertical axis of the arrangement, the conductor 4| extending from the member Ib oi the unit A to the member 1 of the unit B and the conductor 4|', in the case of a three-unit switch, extending from the member |b of the unit B to the member 1 of the unit C.

It now will be appreciated that the above-described basic interrupting unit constructed in accordance with my invention as exemplified in Fig. 1, which includes a metallic arcing chamber comprising a main body portion from which two cylinders or sleeves extend outwardly in different directions, one cylinder for receiving an easily removable insulated contact element and the other for receiving an easily removable contact element which is electrically connected to the chamber body, provides a very useful and desirable arrangement which is readily adaptable for a variety of different applications; for it will be apparent that Whereas one connection of the circuit through the unit must be made at the terminal Ib of the bushing 4, the other connection may be tapped off from any appropriate point at the metal casing 3 which is most convenient for the particular application in View.

In the above-described examples, it will be clear that three such convenient optional tap-olf points from the chamber 3 were employed. There were, firstly, either the member 1 or I4 of Fig. 1 in the case of the arrangements illustrated by Fig. 2 and the unit A of Fig. 5; secondly, the cover 48 of Fig. l in the embodiment shown by Fig. 3; and thirdly, the clamping member 4a of Fig. 1 in the case of units B and C depicted in Figl 5.

Furthermore, the all-metal construction of the chamber 3 provides a strong fluid pressure confining casing in which the arc is drawn and blasted and which chamber moreover constitutes a mechanically strong rigid structure for mounting upon its hollow insulating pedestal and upon which may readily be stacked additional series interrupting units of similar configuration as clearly shown by Fig. 5. In all these various embodiments, it will be observed that the breaking of the one joint at flange |5 of cylinder 6 for the contact 2 is all that is necessary in order to inspect the condition of the contacts or for the removal of the retracting Contact element for repair cr replacement; moreover, these operations are possible without having to disturb any line terminals in the process.

Reverting to Fig. 1, it will be seen that the upper Wall of the contact chamber 3 is provided with an opening 41 which as shown in Fig. 1 and in the arrangements shown in Figs. 2, 3 and 4, is closed by a cover member 48. In the application of the units of Fig. 1 to the arrangement shown in Fig. 5, or similarly for other arrangements of multi-break switch' comprising two or more units stacked one above the other, the cover plate 48 is omitted from the unit A so that the tubular insulating pillar 4D will register with the opening 41 in said unit whereby the air or gas under pressure will also be delivered from the conduit |2 t0 the unit B and any further units mounted above the unit B, the insulating bushings such as 40 housing, if desired, an insulating conduit corresponding with that shown at |2 in Fig. 1. Th'e separation of adjacent units in the same vertical column such as the separation provided by the insulating

pillars

40 and 40 may be graded so as to obtain uniform distribution of voltage between the several pairs of arc-interrupting contacts.

Fig. 6 shows an arrangement comprising a plurality of arc-interrupting contact units in accordance with Fig. 5 and incorporating a further feature of the invention hereinbefore referred to whereby the severalunits are maintained in the required position with respect to one another with the insulating pillars operating under compressive stress only. Each of the contact chambers is provided on its lower external face with a circumferential flange 50 surrounding the open ing at this flange registering with a bore of the insulating pillar ||l in the case of the unit A and with the bore of the insulating pillar 4|lin the case of the unit B. The assembly of insulating pillars and contact chamber units is shown mounted upon the upper wall, partially shown at 5|, of an air storage tank or other foundation member, said wall being provided with an opening on which is seated a ring member 52 against which abuts the lower end face of the pillar l0.

In the case of the unit A the cover member 43 (Fig. 1) is replaced by an annular space-r member 53 having a flange 54 seating on the upper external face of the contact chamber 3 of said unit, this spacer member 53 registering within the opening 41 (Fig. 1) of said contact chamber and within the bore of the insulating pillar 40. The insulating tube |,2 extends from the tank 5| th'rough the opening |I in the lower wall of the contact chamber 3 of the unit A, the spacer member 53, the opening Il in the lower wall of the contact chamber 3 of the unit B and through the opening 41 (Fig. 1) in the upper wall of the last-mentioned contact chamber, said insulating tube |2 being provided with openings at 55 and 55 through which openings th'e pairs of contacts 2 of the two units A and B respectively extend. At its lower end the tube |2 has secured thereto a metal sleeve 51 which registers Within the bore of the member 52 and of the insulating pillar I0 and which is provided with a flange 5B abutting against th'e end surface of the member 52. An air supply conduit is partially shown at 59 making a flanged joint with the flan-ge 58, this conduit being connected with a control valve whereby the air pressure within the tank 5| may be supplied to the tube |2. At its upper end the tube |2 has secured thereto a metal end closure member 60 which registers within the opening 41 in the unit B and is externally screw-threaded to receive a ring nut Gl abutting against the upper external face of the contact chamber 3 of said unit B.

It will be seen that tightening of the ring nut El against the upper face of the chamber 3 of the unit B will place the insulating tube l2 in tension against the abutment of the flange 58 on the member whereby the insulating pillars iii and i2 are placed in compression so that whereas said outer insulating members IQ and iii may be fern ed of porcelain or other ceramic material not well adapted for operation in tension, the internal pillar i2 may be formed of material having esirable properties for operation in tension, for exampie said inner tube may be formed of vulcanite or akelite paper. It will furthermore be seen that the arrangement is such that all the parts are retained in coaxial relation to one another by the flanges 50 and the members S, 5l and Si).

If desired capacitance or other grading means may be provided for edecting a uniform, or other desired gradn oi, distribution of potential between the several pairs of (3o-operating contacts of the switch such as to obtain a uniform distribution of potential between the several breaks and accordii to a further feature of the ine vention said means are obtained by suitable proportioning of the capacitance of the tubular members bet veen the adjacent contact arrangements. For this purpose said tubular members may be provided therein with layers of conductive material in the same manner as a, condenser bushing or the members may be formed of a material having a suitably high specific inductive capactiy such as, for example, the materia-l sold under the registered trade-mark. Rutile.

Fig. 7 shows a modified arrangement of two contact chamber units according to Fig. l to form a doublmbreak switch. In the arrangement shown in Fig. 7, the upper unit B instead of being mounted upon the lower member A. by means of an insulating pillar as in Fig. 5, is mounted directly thereon so as to be in electrical connection therewith. The insulating bushings 4 of the two units extends in diametrica-lly opposite directions from the Vertical axis of the arrangement the ccductors 33 and 34 to be controlled by the sv ch are connected on the one hand with the member lb oi the unit B and on the other hand with the corresponding member ib of the unit A. The unit A is shown by way of example as carrying on the plate 5b thereof a dried contact ctn-operating with a pivoted blade fl? corresponding with the arrangement of isolator switch shown in Fig. 5.

The arrangement of the contact chambers 3 may be identical with that shown in Fig. l except that the two units are connected together by mating franges and 8S formed respectively on the upper face or the unit A and the lower face of the unit B.

It will be appreciated that with the arrangement shown in Fig. '7 additional units may be mounted above the unit B so as to be connected in series therewith and furthermore, if desired, in place of the two or more separate units, the several contact chambers may be formed inte grail with one another by a single metal construction, that is to say in eiiect the insulating bushings @i and cylinders for all the units may be mounted in a common Contact chamber.

Fig. 8 shows a modication of the contact unit of Fig, l, and applicable in the various applications of the units as described with reference to Figs. 2 to '7 inclusive, in which, instead of the movable Contact 2 being mounted in conductive relation with the arcing chamber, said contact 2 is insulated from id chamber. Thus, in Fig. 8 the moving Contact 2 and piston 2a together with the resL ent annular contact 8 are mounted within a. member l0 which is received wn 1e ci second insulating bushing ii le cylindrical portion i chamber S, replacing the cylinder o h that a-t 5 which, as shown in F locates the insulating bushing 4. In tment shown in Fig. 8 the cylindrical ier is provided with a portion i3 of redt eter providing a flange against which the awnilar contact 8 abuts to provide reaction corvicession spring 9 and pr riding e of the discharge passage through larger than the cro contact 2 but somewhat sectional area or that Within said contact cylindrical bushing assembly 78, "Fl is, oncentrically by means gainst 'the inner end of Gans of the end plate relation to the porst the outer end face of a the bushing 5 having screw i in piace within the arcing chamber by The busl cylindrical portiev means oi anna.

the movable conremoved from the arcing chamber when on and replacement of the contacts required.

It will be understood i arrangements shown in the contacts the latter, or

y t if desired in the gs. l and 8 access to of or attention to a id to the Contact I, may be ganeo oi' the bushing 4 from the arcing' chamber le Jushing is located in place by means removable annular retai ling ring 51d secured to the contact chamber by or" ^own. In the case of l however, :ction or' and attention to the contact l h lie cylinder E after removal of the movi ing or the i bushing and the arcing chamber is tl-e t where desired both may be provided with a n 2c described with refnd working within copiston erence operating cylinders, by both the contacts are ad pted to be displaced by the air or gas pressuiv to efec4 the arc emt'nguishing contact separation. For e: nple, in the arrangements of both F 8, the contact l and bushing G may be arranged similarly to the contact 2 and bushing li It will b einents according to the inven'io nos further advantage, for nirreali switches, of redt ci only a coinparatively small "cribcd several embodigas 1elast interrupter unit c ntacts are arranged t 1ection substantially perpendicular to salu units hoilow fluid conducting and si porting insulating to separate ou structure, which unit is economical. to manufacture, easy to assemble, readily accessible and adaptable for various practical applications; it should be understood that my invention is not limited to specific details oi cons ructicn and arrangements herein illustrated, and that changes and modications may occur to one skilled in the art, without departing from the spirit of my invention.

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

1. An electric circuit `breaker of the gas blast type comprising an arcing chamber formed of metal, a plurality of relatively movable contacts associated with said chamber and arranged to draw an arc in said chamber upon relative sellaration thereof, hollow insulating structure for supporting said arcing chamber, means for supplying gas under pressure to said chamber for arc extinguishing purposes through said hollow insulating structure, said metallic arcing chamber comprising a hollow body portion within which said contacts separate, an apertured base portion for said body adapted for mounting upon said hollow insulating structure, a rst sleeve branching laterally koutward from said body in one direction, a second sleeve branching laterally outward from said body in another direction, means disposed in said rst sleeve for supporting one oi? said contacts insulatingly with respect to said metallic arcing chamber, means cooperating with said second sleeve for supporting therein another of said contacts conductingly with respect to said metallic arcing chamber, and a discharge opening from said chamber for exhausting the gaseous products of said arc.

2. An electric circuit breaker oit the gas blast type comprising an arcing chamber formed of metal, a plurality of relatively movable contacts associated with said chamber and arranged to draw an arc in said chamber upon relative separation thereof, hollow insulating structure for supporting said arcing chamber, means for supplying gas under pressure to said chamber for arc extinguishing purposes through said hollow insulating structure, said metallic arcing chamber comprising a hollow body portion within which said contacts separate, an apertured base portion for said body adapted for mounting upon said hollow insulating structure, a rst sleeve branching laterally outward from said body in one direction, a second sleeve branching laterally outward from said body in another direction, means disposed in said first sleeve for supporting one of said contacts insulatingly with respect to said metallic arcing chamber, means cooperating with said second sleeve for supporting therein another of said contacts conductingly with respect to said metallic arcing chamber, one of said contacts being hollow thereby deiining a discharge opening from said chamber for exhausting the gaseous products of said arc.

3. An electric circuit breaker of the gas blast type comprising an arcing chamber formed of metal, a plurality of relatively movable contacts associated with said chamber and arranged to draw an arc in said chamber upon relative separation thereof, means including a piston and a closing spring associated with one of said contacts to define therewith a retractable contact, means for supplying gas under pressure to said chamber for causing relative separation of said contacts and extinguishment of the arc drawn therebetween, said metallic arcing chamber comprising a body portion within which said contacts separate, means for supporting one of said contacts insulatingly with respect to said body, a sleeve branching laterally outward from said body, means cooperating with said sleeve for supporting therein said retracting contact, a readily disconnectable joint for said sleeve the breaking 10 of which suffices for the removal of said retractable contact, and a discharge opening from said chamber for exhausting the gaseous products of said arc.

4. An electric circuit breaker of the fluid blast type comprising a structure defining an arc extinguishing chamber, a pair of relatively separable contacts arranged to draw an arc in said chamber, a fluid motor for causing relative separation of said contacts, means for supplying fluid under pressure to said chamber to operate said fluid motor and to provide an arc extinguishing medium adjacent said contacts, said arc eX- tinguishing chamber comprising a hollow metallic body portion within which said contacts separate, an apertured base portion for said body adapted for mounting on a hollow insulating supporting structure through which said fluid is supplied, a sleeve extending laterally outward in. one direction from said body for supporting one of said contacts and said fluid motor, an electric bushing extending laterally outward from said body in another direction for supporting the other said contact insulatingly with respect to said body, a readily disconnectable joint for said sleeve the breaking thereof suflicing for the removal of said iluid motor and providing direct access to said contacts, one of said contacts being hollow thereby deiining a discharge opening from said chamber for exhausting the gaseous products of said arc.

5. A multi-break electric circuit breaker comprising a plurality of identical arcing chambers eachhaving a pair of relatively movable contacts associated therewith, each of said arcing chambers including a hollow metallic body within which said contacts separate to draw an arc, a iirst opening in one end of said body, a second opening in the opposite end of said body in axial alignment with said first opening, means associated with said rst opening to provide an interlocking male portion for matching with said second opening, means for stacking said arcing chambers one above the other in a column whereby adjacent chambers interlock together with all said openings in axial alignment so that said chambers communicate with each other, means for supplying iluid under pressure to one of said chambers and consequently to all of said charnbers through said aligned openings, and means for causing relative separation of all said pairs of relatively movable contacts in response to the supplying of fluid under pressure to said chambers.

6. A multi-break electric circuit breaker comprising a plurality of identical arcing chambers each having a pair of relatively movable contacts associated therewith, each of said arcing chambers including a hollow metallic body within which said contacts separate to draw an arc, a rst opening in one end of said body, a second opening in the opposite end of said body in axial alignment with said iirst opening, means associated with said first opening to provide an interlocking male portion for matching with said sec- 0nd opening, means for stacking said arcing chambers one above the other in a column including a tubular insulator interposed between each adjacent pair of chambers, means associated with each said insulator to provide an interlocking male portion at one end and a bore at the opposite end similar to the first and second openings respectively in each said arcing chamber whereby all said stacked chambers and insulators interlock progressively with holes and bores in axial alignment, means for supplying iiuid under pressure to one of said chambers and consequently to all of said chambers through said aligned openings, means for causing relative separation of all said pairs of relatively movable contacts in response to the supplying of fluid under pressure to said chambers, and means for connecting said pairs of contacts in series relationship.

7. A multi-break electric circuit breaker comprising a plurality of identical arcing chambers each having a pair of relatively movable contacts associated therewith, means for stacking said arcing chambers one above the other in a column, the adjacent walls of any two adjacent chambers being provided with aligned openings so that said chambers communicate with each other, a tubular member of insulating material extending through said aligned openings from end to end of said column, means for supplying fluid under pressure to one of said chambers and consequently to all of said chambers through said tubular member, and means for causing relative separation of all said pairs of relatively movable contacts in response to the supplying of iluid under pressure to said chambers.

8. A multi-break electric circuit breaker comprising a plurality of identical arcinfJr chambers each having a pair of relatively movable contacts associated therewith, means for stacking said arcing chambers one above the other in a column, the adjacent walls of any two adjacent chambers being provided with aligned openings so that said chambers communicate with each other, a tubular member of insulating material extending through said aligned openings from end to end of said column, an insulating tube between each of said chambers, means for placing said tubular member in tension and consequently said insulating tubes in compression, means for supplying iluid under pressure to one of said chambers and consequently to all of said chambers through said tubular member, and means for causing relative separation of all said pairs of relatively movable contacts in response to the supplying of fluid under pressure to said chambers.

9. A multi-break electric circuit breaker comprising a plurality ci identical arcing chambers each having a pair of relatively movable contacts associated therewith, means for stacking said arcing chambers one above the other in a column, the adjacent stalls of any two adjacent chambers being provided with aligned openings so that said chambers communicate with each otn a tubular member of insulating material extending through s i aligned openings from end to end oi said columns, an insulating tube between each of said chambers, means for placing said tubular memL in tension and consequently said insulating tubes in compression, means for supplying uid under pressure to one of chambers and consequently to all of said chambers through tubular member, means for cau ng relative separation of all said pairs of relatively movable contacts in response to the supplying of fluid under pressure to said chambers. and means for connecting said pairs of contacts in series relation -p4 CEDRIC HAROLD if URSCHEIM.

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

UNITED STATES PATENTS Number Name Date 695,118 Read Mar. 1l, 1902 1,144,047 Merrian June 22, 1915 1,904,577 Uebermuth Apr. 18, 1933 2,255,198 Thommen Sept. 9, 1941 2,125,525 Thomien Aug. 2, 1938 2,253,196 Paul Aug. 19, 1941 2,306,242 Bartlett Dec. 22, 1942