US2228432A

US2228432A - Circuit interrupter

Info

Publication number: US2228432A
Application number: US237264A
Authority: US
Inventors: Benjamin P Baker; Andrew H Bakken
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1938-10-27
Filing date: 1938-10-27
Publication date: 1941-01-14
Anticipated expiration: 1958-01-14
Also published as: CH217863A; GB534979A; FR861118A; BE436835A; GB537069A; NL60719C

Description

Jan. 14, 1941. B p. BAKER EAL 2,228,432

CIRCUIT INTERRUPTER fd WM ml, Y Andrew H. Bakken BY l' ATToRNE Jan. 14, 1941. B. P. BAKER Erm.

CIRCUIT INTERRUPTER Filed oct. 27. 193e 6 Sheets-Sheet 2 sym RIH'K Oak. Ta NEB E wmH -mm WITNESSES' ATTORNEY Jan. 14, 1941. B. P. BAKER ErAL 6 Sheets-Sheet 3 Andrew H. Bak kan BY INVENTORS Benjamin f. Ba her ATTORNl Jan. 14, 1941. B. P. BAKE ErAL CIRCUIT INTERRUPTER Filed Oct. 27, 1938. 6 Sheets-Sheet 4 .a Sr im E Tak N NBk R E a O W5 n HNA mw wd 5M .AM

Jan. 14, 1941. B. p, BAKER HAL 2,228,432

CIRCUIT IN-TERRUPTER Filed Oct. 27, 1958 6 Sheets-Sheet 5 I INVENTORS 92ml. C W en/'amm Baz/fer d? lJan. 14, 1941.

CIRCUIT INTERRUPTER Filed Oct. 27, 1958 WlTNESSES:

6 Sheets-Sheet 6 Hg. /a

F/ J3. 48 y INVENTORS Benjamin R a/fer Andrew H. Bak/ren Patented Jan. 14, 1941 UNITED sTATEs PATENT OFFICE CIRCUIT INTERBUPTER .Aspiration october 27,19%,v sel-rails. 231,264

22 Claims.

This invention relatesto hig -voltage highpower circuit breakers and mo particularly to improvements in the circuit interrupting elements therefor.

In the application oi B. P. Baker, Serial No. 230,946, tiled September 2l, 1938, and assigned to the assignee of this application, is disclosed a -circuit breaker of the high-voltage high-power type in which circuit interruption isf' accomplished by two or more serially connected circuit interrupting elements. Each of the interrupting elements shown and' described in the aforesaid application consists of a cylindrical casing approximately one-half of which is` utilized to supl5` port acorrugated wall arc chamber, whereas the other half serves as an expansion chamber into which arc gases are discharged.

A stationary contact assembly is provided in each expansion chamber consisting of a plurality terminate adjacent the open end .of the arc chamber'and are adapted to cooperate with a ring contact carried by a movable operating member passing axially through both interrupting elements. The movable contact ring is adapted-to be brought into sliding contacting engagement with the contactsurfaces of the stationary contact ilngers during the closing operation of the breaker. We have discovered that in the event of appreciable misalignment of the movingand fixed contacts as well as burning and pitting of the beveled leading edges of these-contacts, the movable contact sometimes positivelyoengages the leading tips of the stationary contact fingers and -preve'nts the moving lcontact from sliding into its tlnal contacting position. v Y It is an object of our invention to provide a contact structure for circuit breakers oi the fo'regoing type which is freely movable to the closed circuit position even though -the stationary and movable contacts are out of alignment or become pitted from arcing as a result of 'repeated circuit opening operations. l

A further and more speciiic object o! our invention is the provision of a contact structure of Athe tulip type for circuit breakers in which provision is made for moving the stationary contact lingers laterally at right angles to the movement of the moving contact ,in response to a positive engagement of the moving contact with the stationary contact lingers during the closing stroke ofthe breaker so as.to permit the moving contact to slide unopposed into ilnal contacting engager ment with the stationarycontact fingers.

oi! contact fingers, the contact muffaces of which,

In'circuit breakers of the type shown and de- (Cl. 200-) i scribedj in the aforesaid application, which are capable of interrupting a large number o! volts per inch of contact separation, it is desirable and advisable to frequently flush the interruptingelements with clean arc extinguishing liquid so as to prevent carbonized products of decomposition of the liquid fron forming a conducting nlm upon .the insulating surfaces of the arc extinguishing structure. Frequent flushing of the arc extin, guishing devices" is of particular importance in circuit breaker structures of Kthe type wherein the arc extinguishing devices have a relatively small capacity for retaining arc extinguishing liquid.

A further object of our invention is to provide nushing means for the interrupting'elements'of circuit breakers of thehigh-voltage type-whereby the rc extinguishing structure is subjected to the fio of clean arc extinguishingliquidfollowing each -circuit interrupting operation.

Another object of our invention is the provision of a ilushing device for circuit interrupting elements which is self-contained in the interrupting unit and actuated by the same resilient means used for moving the movable contact mechanism to the open circuit position.

Stillganother objectof our invention is the provision ofa high-power circuit breaker having a main operating spring for moving the movable A contact lassembly to the open circuit position, which-spring is also employed for actuating a ushing device for the arc extinguishing' elements after each circuit opening operation and which is further used for controlling the release of 'pressure within the interruptr housing.

Other objects and advantages relate to details of ourk circuit breaker structure and to the ar'` rangement of the various parts thereof. all of which will appear more fully in the following description when read in connection with the accompanying drawings, in which: l

Figure `l lis a side elevation v iew partially inv section showing the circuit breaker of ouil invention;

Fig. 2 is an elevation view partially in section of the interrupting unit of the breaker shown in Fis. 1: l

Fig. 3 is a cross sectional view ot the interrupting unit .shown in Fis. 2, taken along the line III-HAI; ,x

Fig. 4 is another cross sectional view of the interrupting element Lof Fig. 2, taken along the line :lV-Iv.; t f* Fig. 5 is a fragmentary sectional view of the stationary contact assembly, as viewed along the line v-V of Pls. 3;

Fig. 6 is a plan view of a casing member forming part of the liquid pumping structure of the interrupting unit shown in Fig. 2;

Fig. 7 is a sectional View of the casing member shown in Fig. 6, taken along the line VII-VH;

Fig. 8 is a cross sectional View of the interrupting unit of Fig. 2, taken along the line VIII-VEL showing further details of the liquid pumping structure;

Fig. 9 is a vertical sectional view of the liquid pumping structure shown in Fig. 8, taken along the lineD-IX;

Fig. 10 is a cross sectional view of the interrupting unit of Fig. 2, taken along the line X--X thereof with certain portions of the unit omitted; Fig. 11 is a fragmentary vertical sectional view taken along the line XI-m of Fig. 10;

Fig. 12 is a cross sectional view of the interrupting element shown in Fig. 2, taken along the line XII-XII of that figure with certain portions of the element omitted; and

Fig. 13 is a fragmentary vertical sectional view taken along the line XIII-X111 of Fig. 12.

Referring to the drawings, the reference number I5 designates a metal casing having an upper support plate I1 whichcarries a hollow insulator |9 of weatherproof material, such as porcelain or the like. Upon the upper end of the insulator |9 is seated an annular plate 2| which carries a metallic dome-shaped closure 23. The hollow insulator i9 is maintained in position by a tubular strain member 25, preferably of insulating material, which is secured at its lower end to the support plate and at its upper end to an annular plate 21 which, in turn, is bolted to the annular plate 2|.

The metallic casing I5, the insulator I9; in conjunction with the tubular strain member 25,

and the upper closure 23, provide a housing which is adapted to be filled with arc extinguishing liquid and in which a circuit interrupting unit 29 is immersed. The circuit interrupting unit 29 comprises two interrupting elements 3| and 33 joined by a iianged casing 35. A second iianged casing 31 is secured to the upper end of the interrupting element 3| and is provided with a plurality of, in this instance, four laterally extending support arms 39. The support arms 39 are releasably secured to the annular plate 21 and serve as the sole support for the interrupting unit 29 within the breaker housing.

The interrupting elements 3| and 33 each consists of a tubular casing member 4| of insulating material, the ends of which are provided with suitable metallic collars 43 to which the respective

iianged casings

35 and 31 may be secured.

Disposed within the casing 4| are a plurality of

Washers

45 and 41 of insulating material of different internal diameter alternately disposed in stacked relation so as to provide an arc chamber 48 having corrugated wall surfaces. The space above the

washers

45 and 41, as defined by the casing 4| and the iiange member 31, constitutes an expansion chamber 49 in which arc gases may be discharged and in which the stationary contact assembly of each interrupting element is adapted to be housed. This stationary contact assembly, as shown in Figs. 2 to 5, inclusive, consists of a plurality of contactl ngers 5| disposed in substantially parallel relation with respect to each other and supported by a generally tubular support member 53. The support member 53 has an outwardly extending flange 55 which is adapted to be clamped between the anged casing member 31 and the upper collar 43 of the interrupting element 3|. In the interrupting element 33, the ange 33 is clamped between the flanged casing 35 and the upper collar 43 of that element. .l

Each of the contact lingers 3| of the interrupting element 3| is connected by means of a flexible shunt 51 to the flanged casing 31. The moving contact assembly comprises an operating member 59 extending axially through the arc chambers 48 and the expansion chambers 43. This member carries a contact ring 3| having outwardly extending contact surfaces 33 thereon which are adapted to make sliding contact-engagement with the contact fingers 5|,

Disposed immediately above the contact ring 6| are a plurality of

Washers

35 and 31 of insulating material and of different external diameter alternately arranged in stacked relation so as to form a corrugated piston member 33, which is adapted to be moved with the contact ring 3| into the arc chamber 43 during the opening movement of the interrupter. The washers 33 have an outside diameter with respect to the in-' side diameter of the Washers 45, such that when the piston member 69 has been moved into the arc chamber 48, the piston member confines and limits the arc chamber to a narrow elongated passage of relatively small cross section.

The left-hand contact surface. of the contact ring 6 I, as viewed in Fig. 2, has considerably greater length than the remaining contact surfaces, so as to cause the left-hand contact surface to separate last in the point of time from the left-hand contact finger 5| to insure drawing the arc Within the elongated arc passage formed between the4

stationary washers

43 and 41 and the piston member 33.- The piston member 69 during its movement to the open circuit position displaces arc extinguishing liquid from stream and assists in expelling arc gases from the arc chamber 43 into the expansion chamber 49.

` The interrupting element 33 is generally similar in construction to the construction of the element 3| except that theilexible shunts 31 of the element 33 areV connected to a tubular sleeve 1| carried by the operating member 33. The tubular sleeve 1I is of metallic material and is connected electrically with the contact ring 3| of the interrupting element 3|, thereby providing a series electrical connection between the two interrupting elements.

'Ilhe contact ring 3| for the interrupting element 33 engages a metallic c'ap member 13 .secured to the lower end of the operating member 59, which cap member engages a plunger member 15 (Fig. 1) supported by a suitable Astraightline operating mechanism generally indicated at 11 in Fig. 1. The plunger member 13 is conynected by a flexible shunt 13 to a terminal 3| extending through the side oi' the casing I3. A second line terminal 33 is provided which extends through the side of the closure member 23 and is connected by afiexible connector 33 to the nanged casing 31. Thus, the electrical circuit through the circuit breaker proceeds from the line terminal 33, connecwr 33, casing 31, nexible shunts 51, contact nngers 3|, contact ring 3|,

metallic sleeve 1|, to the flexible shunts 31 (not.

kso

to the cap member 13, the plunger member 15, flexible'connector 19, and terminates at the, line terminal 8|'.

The operating mechanism 11 is utilized primarily to move the operating member 59 and its associated parts to the closed circuit position. 'I'he movement of the operating member 59 to the open circuit` position is accomplished by means of a battery of compression springs 81 located within the dome-like enclosure 23 and disposed between two

movable pressure plates

39 and 9|. The pressure plate 9| is secured to the upper end of the operating member 59, as shown in Figs. 1 and 2, and directlytransmits the force .from the springs 81 to the operating member to move it to the open circuit position when released by the straight-line operating mechanism 11.

The leading tips of the contact surfaces 53 are rounded so as to normally permit the contact ring 8| to slide into contacting engagement with the contact surfaces of the contact fingers. In the event that the contact fingers .and the contact ring become greatly out of alignment, or in the event that the leading tips become deeply pitted or burned so as to destroy the rounded edges, the contact rings 6| will not slide freely to theirI final closed circuit position, but will jam so as to prevent free closing unless provision is made to j prevent the contact fingers from making positive engagement with the moving contact rings.

As more clearly shown in Figs. 3 to,5, we have provided an arrangement for supporting the con tact fingers 5I with respect to the support casting 53 so that when the contact fingers makepositive engagement with the contactI ring lII during the closingmovement, the contact fingers will be carried aY short distance with the contact ring. 'I'his longitudinal movement of the contact fingers 5| is utilized tocause a lateral movement of the fingers at right angles to the path of movement of the contact ring 5| so as to release the positive eng/agement between the contact fingers and the contact ring, thereby permitting the ring to slide freely to its'fully closed position. To accomplish the foregoing, the contact fingers 5| are disposed about the outer circumference of the cylindrical supportcasting 53,

andextend upwardly through a rectangular aperture 93 formed in the flange 55 which serves 'as a guide to prevent lateral movement circumferentially of the casting 53. Further guide means are provided by outwardly projecting bosses 95L formed at the lower end of the cylindrical casting 53. Thus, it will be seen that the apertures 93 and the bosses 95 permit lateral movement of the contact fingers 5| in a direction radially of the cylindrical casting 53. The upper end of each contact finger 5| is provided with two laterally extending projections91, as shown in Figs. 3 and 5. The projections 91 are disposed between the flange 55, which supports the cylindrical casting 53, and a second outwardly extend- I ing flange 99 located at the upper end of the cylindrical casting 53. The upper ange 99 is spaced some distance above the support flange 55 so as to permit a limited amount of longitudinal movement of the contact finger 5| with respect/to the cylindrical support casting 53.

Each of the contact fingers 5| is provided with ac-cam surface |I which is adapted to engage a y similar cam surface |03 disposed at the lower edge of the casting 53 so as to cooperate with the corresponding cam surfacey on the contact finger. A plurality of coil springs |05, in this instance two, encircle the 'contact fingers 5| so as to bias them towards the support casting 53 and also bias them into engagement with the contact rings 8| when Vthe interrupter is in the closed circuit position. y

As shown in Figs. 2 to 5, inclusive, it will be apparent that the cam surfaces |0| and |03 are such that in the event that the contact ngers are moved upwardly by the positive engagement with the contact ring 6|, the contact fingers 5| will be moved outwardly, thus releasing the positive engagement between the contact fingers and the contact ring so as to permit the contact ring to move to its final contacting position. Thelower biasing spring |05 is alternately ,looped on top of a boss |01, secured to each contact finger 5|, and below a similar boss |09, secured to the outer circumference of the support casting 53, as more clearly. shown in Fig. 5.-

, It will thus be seen that the lower spring |05.

also biases the contact Afingers 5| downwardly so that upon following a disengagement of the contact fingers from the moving contact ring, as a result of longitudinal movement upwardly of the contact fingers, the contact fingers will again be moved downwardly to their normal position so as to insure a spring pressed engagement with the contact ring. y l ,The main operating springs are also utilized in controllingV the release -of pressure within the housing during and following circuit interruption. The arrangement whereby this is accomplished is set forth in detail in the application of il.. H. Bakken, Serial No. 230,948, flied September 21, 1938, now Patent No. 2,199,607, issued May 7, 1940, and assigned to the assignee of the instant application. I

As set forth in the aforesaid application of A. H. Bakken, the

movable pressure plates

39 and 9| are provided with four apertures ||I and I3, respectively, through which four guide and support rods ||5 extend. Each guide and support rod I I5 is secured at its lower end to a respective support arm 39. The upper end of the guide rods ||5 are united with a stop plate ||1 against which the movable p'ressure plate 89 ls normally urged by the operating springs 81. To the upper side of the stop plate ||1 is secured an upstanding box-like support ||9 each of the four sides of which is provided with a rectangular preferably comprises a lower cylindrical section |33 and an upper cap member |35, which cap isv releasably seated upon the cylindrical section |33. rI'hebolt |21 is provided with a nut |31 for placing the bolt in tension so as to draw the head thereof towards the bushing |29 in the cap |35 which at the same time,- raises the levers |23 so that they fulcrum about the upper edges of the f rectangular apertures |2| in the box-like support l I9 and produce a downward force at their outer ends acting upon the adjustable screws |3| and consequently act to move the presure plate 89 downwardly against the springs 81. It clearly follows that the springs 81 apply a biasing force through Ithe movable pressure plate 89,the levers |23 and the bolt |21 to yieldingly maintain the cap |35 in position. ,Itis also apparent that the existence of pressure, within the breaker housing of a predetermined value, will cause the cap member |35 to be lifted against the action of the lmain operating springs 81 so as to permit the 5 pressure to be relieved within the interrupter housing.

The main operating springs 91 are also utilized to actuate a liquid pumping device for flushing the arc chambers 48 following each lo circuit interrupting operation. The liquid circulating device and the manner of its association with the main operating spring will now be described. The nanged casing 31 is provided with a cover plate |39 which has an upstanding l5 collar i4! through which the upper end of the operating member 59 extends and is guided during its reciprocating movement. Movable about the upstanding collar 4| is a cylinder |43 having the side wall |45 (Figs. '7 and 9) slidably engaging the outer circumference of the cover plate |39. The movable cylinder |43 has four outwardly projecting ears |41 provided with suitable apertures through which the guide rods ||5 extend and maintain the cylinder in proper alignment during its reciprocating movement. A coil spring |49 encircling each guide rod i5 and disposed between a support arm 39 and an ear |41 normally maintains the cylinder |43 in the upward position so as to providean annular chamber |5|. Liquid is admitted into the chamber |5| by a simple valve arrangement comprising an annular channel |53 machined in the lower side of the cylinder |43, which channel communicates with the liquid above the cylinder through a plurality of apertures |55, as more clearly shown in Fig. 8. The apertures |55 are normally open but are adapted to be sealed during the downward stroke of the cylinder |43 by a oating annularly-shaped valve member |51 4() slidably supported on pins |59.

The collars 43 are provided with radially extending passages |13, as shown in Figs. 10 to 13, inclusive. The passages |13 terminate in an annular channel |15 at the base of the respective 65 arc chambers 48. It will thus be seen that as the cylinder |43 is moved downwardly, the liquid therein will be forced through the passages |61 past the check valve |69, through the conduits |6| and |63, through the passages |13 and into the annular channels |15 and then upwardly through the arc chambers- 48 in the direction shown by the arrows in Figs. 11 and 13. Movement of arc extinguishing liquid through the arc chambers 48 in this manner following each circuit interrupting operation flushes out the arc chambers 48 removing products of decomposition produced by the arc acting upon the liquid during arc extinction and thereby prevents the settling of the solid products upon the insulating surfaces of the arc chamber which 5 would impair the insulating qualities thereof.

As heretofore stated, the movable cylinder |43 is maintained in its raised or uppermost position by the springs 49. Movement in the downward direction so as to cause a discharge of liquid 10 from the chamber |5| is produced by auxiliary spring means which are charged during the opening stroke of the operating member 59 by direct action of the main operating springs 81. More speciiically, the movable cylinder 43 is provided 15 with a plurality of, in this instance four, tubular guides |11 secured about the outer periphery thereof, being open at the top and closed at the bottom except for an aperture through which an operating bolt |19 extends. An auxiliary op- 20 erating spring |8| encircling the bolt |19 and disposed within the tubular spring guide |11 normally maintains the bolt |19 in its uppermost position. The movable pressure plate 9|, which directly actuates the operating member 25 59, is provided with four outwardly extending ears |83 which register with the heads of the bolts |19 so that when the pressure plate 9| is moved downwardly, the ears |63 engage the bolts |19 and compress the springs |8| prior to 30 the time the pressure plate 9| reaches its lowermost or full open position.

The combined tension of the springs |8| is less than the tension of the main operating springs 81, which makes compression of the 35 springs |8| possible by means of themain operating springs 81. Thus, the movable cylinder |43 is rendered operative during the opening movement of the operating member 59 by the direct action of the main operating springs 81. 40 The cylinder |43, however, is not moved downwardly to discharge the liquid contained within the chamber |5| until the pressure within the arc chambers 48 of the interrupting elements 3| and 33 has been reduced to a predetermined 45 value, such as will permit the springs |8| to move the cylinder |43. In other Words, the main operating springs 81 merely place the moving cylinder |43 in readiness so that when suitable pressure conditions exist Within the arc 50 chamber following arc extinction, the cylinder becomes eiiective to force clean arc extinguishing liquid through the arc chambers to rid them of any deleterious substances. This arrangement for actuating the movable cylinder |43 per- 55 mits movement of the operating member 59 and consequently the movable contact ring 6| to the full open position independently of the pressure conditions within the arc chamber set up by the respective arcs, which pressures may, in the ab- 00 sence of the particular arrangement, tend to stop the movement of the operating member to the open position.

lll encircling'the upper end of the operating Imember I9.

This ,spacing provides a layer of liquid between the plates |85 and |81 which must be displaced when thev pressure plate 9| strikes the buffer plate |81, thereby producing the desired buffer action to arrest motion of the operating I member of the breaker without shock to the mechanism. In order to prevent high resistance 20 to the movement of the pressure plate 9| through the arc extinguishing liquid, the latter is preferably perfor-ated, as shown in Fig. 8, which necessitates the use of the buffer plate |81 to obtain the requisite resistance to movement at 25 or near the end of the opening stroke of the operating member 59. It will, of course, be understood that if the movable pressure plate 9| is .inperforated, the same bufilng action may be obtained without the use of the bufilng plate |81.

Although we have shown and described a specific circuit breaker structure, it is to bev understood that the same is for the purpose of illus-l tration and that changes and modifications may 'u be made by those skilled in the art without departing from the spirit and scope of the appended claims.

. We claim as our invention:

i; Ina circuit interrupter, a pair of separable Y contacts at least one of which is movable, said 40 contactshaving slidably engageable surfaces parallel to the general direction of movement of said movable contact, and means cooperating with said other contact for moving said other contact laterallynin a direction away from said movable contact in response to longitudinal movement by said movable contact during the closing movement ci' said contacts to cause said surfaces of said contacts to be brought into alignment.

w 2. In a circuit interrupter, a pair oi'separable contacts, at least one of which is movable, said contacts having engageable surfaces parallel to the general direction of movement of said movable contact, means normally applying a biasing,

u force -at right angles to said contact surfaces for holding said suraces in engagement, and means suDPOrtins said other 'contact for limited'movement both laterally and longitudinally of the path of movement of said movable contact, and

mmeans' operative inresponse to longitudinalv movement o! said other contactl by said movable contact to move said other contact laterally against the bias of said biasing means to cause said contact surfaces to be moved into cooperaas. tive engagement.

3.' In7 acircuit interrupter. a support, a contact finger yieldingly held by said supportfa' moving contact adapted to\make sliding contact longitudinally of said contact nger, and coop- 'I0 erating cam means carried by said support and v said contact finger for moving said contact finger g tact during movement of said .moving contact toward said contact finger.

4. In a circuit interrupter, a contact finger, a support therefor, a moving contact disposed for wiping engagement with said contact finger dur- 5 ing movement to the closed circuit position, said contact fingerv having a predetermined amount of longitudinal and lateral movement with respect to said support, means biasing said contact finger both laterally and longitudinally towards 10 said movingcontact, and means carried by said contact finger and said support for moving said contact finger laterally in a direction away from the path of movement of said moving contact in response to longitudinal movement of said contact finger resulting from a positive engagement of ysaid contact finger with said moving contact during movement of the latter to the closed circuit position to break said positive engagement and effect a wiping contact.

5. In a circuit interrupter,l a contact structure comprising a cylindrical support member, a plurality of contact fingers disposed adjacent the outer surface of said support member, guide means for maintaining said contact fingers substantially parallel Vto the longitudinal axisof said support Y member, said guide means providing limited longitudinal and radial movement of said contact fingers with respect to said support member, a movable operating member extending axially through said support member, a ring con-v tact carried by said operating member the outer surface of which is adapted to make sliding contact with said contact fingers, means biasing said contact fingers into engagement with said 35. ring contact when said operating member is in the closed circuit position, and cam means associated with said contact fingers and said support member for moving said contact fingers radially from said support member in response to longitudinal movement of said contact fingers resulting from positive engagement of said fingers with said ring contact to effect a release of said positive engagement and enable said ring contact to make sliding engagement with said contact iingers.

6. `In a circuit interrupter, a quantity of arc extinguishing liquid, separable contacts, actuating means for operating said contacts to the open circuit "position for drawing an arc within said l liquid, and means actuated by said actuating means and operative in responseito predetermined pressure conditions in the region surrounding said`contacts for moving a quantity of `arc extinguishing liquid which has not been subjected to said arc between said contacts.

-7; rIn a circuit interrupter, an' arc chamber having arc extinguishing liquid therein, separable contacts for establishing an arc within saidarc chamber, actuating means for operating said contacts, means for moving an additional quantity of arc extinguishing liquid through said arc chamber following arc extinction, energy storing means for operating, said liquid moving means following the subsidence of pressure within said arc chamber, and-means for operatively connecting said contact actuating means with said energy storing means to cause said actuating means to store energy in said energy storing means during the opening operation of vsaid actuating means. 7 8. In a circuit interrupter, an arc chamber having arc extinguishing liquid therein, separable contacts for establishing an arc within said arc chamber, actuating means for operating said conztacts, piston means for moving an additional quantity of an extinguishing liquid through said arc chamber following arc extinction, spring jmeans for operating said piston means, and 'means for operatively connecting said contact actuating means with said spring means for stressing the latter during the final movement of said actuating means to the open circuit position.

9. In a circuit interrupter, an arc chamber, a quantity of arc extinguishing liquid therein, a stationary contact, a cooperating movable contact, an operating member for moving said movable contact to open and closed positions, means actuated by said operating member during the opening movement thereof to place an additional quantity of arc extinguishing liquid under pressure, and means operative in accordance with predetermined pressure conditions within said are chamber for causing said additional quantity of liquid to be directed through said arc chamber.

1G. In a circuit interrupter, an arc chamber, a quantity of arc extinguishing liquid therein, a stationary contact, a cooperating movable contarot, an operating member for moving said movable contact to open and closed positions, pumping means for causing an additional quantity of an extinguishing liquid to iiow through said arc chamber, and means coupling said pumping means With said operating member to render said pumping means operative during the opening stroke of said operating member, said coupling means being ineffective to operate said pumping means until predetermined pressure conditions are obtained Within said arc chamber.

11. In a circuit breaker, an enclosure, a body of liquid therein, an arc chamber immersed in said liquid, separable contacts at least one of which is movable, an operating member for said movable Contact, resilient means for moving said operating member to the open circuit position to establish an arc Within said arc chamber, pumping means rendered' operative by said resilient means during the opening movement of said operating member for moving a quantity of said liquid through said arc chamber after arc extinction, and means for preventing a reverse flow of liquid from said arc chamber to said pumping means.

12. In a circuit breaker, an enclosure, a body of liquid therein, an arc chamber immersed in said liquid, separable contacts at least one of which is movable, an operating member for said movable contact, resilient means for moving said operating member `to the open circuit position to estab-` lish an arc Within said arc chamber, said enclosure having pressure relieving means including a vent opening and a releasable cover member therefor, said cover member being biased to the closed position by said resilient means, pumping means rendered operative by said resilient means during the opening movement of said 'operating member for moving a quantity of said liquid through said arc chamber after arc extinction, and means for preventing a reverse flow of liquid from said arc chamber to said pumping means.

13. In a circuit breaker, a housing, a body of liquid in said housing, an arc chamber immersed in said liquid, a stationary contact adjacent one end oi said arc chamber, a cooperating movable contact, a plunger for carrying said movable contact, a spring for moving said movable contact into said arc chamber to establish an arc therein and cause liquid to flow longitudinally of the arc stream `to assist in extinguishing the arc, means forv relieving said housing of pressure produced by said arc including a vent opening and a cover therefor, means operatively coupling said cover with said spring for yieldingly holding said cover in the closed position against the pressure within said housing, and pumping means rendered operative by said spring during movement of said plunger into said arc chamber for moving a quantity of liquid through said chamber, said pumping means being ineffective to move said liquid until the pressure within said arc chamber has been reduced to a predetermined value.

14. In a circuit breaker, an enclosure, a body of liquid therein, an arc chamber immersed in said liquid, separable contacts at least one of which is movable, operating means for actuating said movable contact to the open circuit position to establish an arc in said arc chamber, and means actuated by said operating means during the latter part of its opening movement and operative in response to predetermined pressure conditions in said arc chamber for moving a quantity of said liquid through said arc chamber.

15. In a circuit breaker, an enclosure, a body of liquid therein, an arc chamber immersed in said liquid, separable contacts at least one of which is movable, operating means for actuating said movable contact to the open circuit position to establish an arc in said arc chamber, pumping means for moving a quantity of said liquid through said arc chamber, and means operatively coupling said contact opera'ting means Vwith said pumping means during the. final movement of said operating means to its open circuit position for actuating said pumping means, said coupling means enabling said contact operating means to move to its full open circuit position independently of the liquid pumping operation.

16. In a circuit breaker, an enclosure, a body of liquid therein, an arc chamber immersed in said liquid, separable contacts at least onefof which is movable, operating means for actuating said movable contact to the open circuit position to establish an arc in said arc chamber, pumping means for moving a quantity of said liquid through said arc chamber following arc extinction, spring means for actuating said pumping means, and means operatively coupling said contact operating means with said spring means during the iinal movement of said operating means to its open circuit position for storing energy in said spring means, said spring means enabling said contact operating means to move to its full open circuit position independently of the operation of said pumping means.

17. In a circuit interrupter, a support member, a plurality of contact fingers carried by said support member, a contact means movable axially of said contact fingers and adapted to make sliding engagement therewith, said support member having guide means providing limited longitudinal and lateral movement for said contact fingers with respect to the path of movement of said contact means, and means operatively associated with said support and contact fingers for moving said contact fingers laterally in a direction away from said contact means in response to 6 longitudinal movement of said contact fingers resulting from positive engagement oi said iingers with said contact means during the closing movement of said contact means to effect release o1' said positive engagement and enable said contact means to make sliding contact with said contact fingers.

18. In a circuit interrupter, a Contact structure comprising a cylindrical support member, a plurality of contact fingers disposed adjacent the lited longitudinal and radial movement of said contact ngers with respect to said support member, a contact member movable axially of said support member and having a contact surface adapted to make slidingcontact with said contact lingers, means biasing said contact lingers into engagement with said contact member when said contact member is in the closed circuit position, and means associated with said contact ngers and said supporting member for moving said contact iingers radially from said support member in response to longitudinal movement of said contact lingers resulting from positive engagement oi' said iingers with said contact member during the closing movement of said contact member to effect a release of said positive engagement and enable said contact member to make sliding engagementwith said contact fingers.

19. Iny a circuit interrupter, an arc chamber having arc extinguishing liquid therein, separable contacts for establishing an arc within said arc chamber, actuating means for actuating said contacts, means i'or moving an additional quantity of arc extinguishing liquid through said arc chamber, energy storing means for operating said liquid moving meansin response to predetermined pressure conditions within said arc chamber, and means for operatively connecting said contact actuatingmeans with said energy storing means to cause said actuating means to store said energy in said energy storing means during the opening operation oi' said actuating means.

20. In a circuit breaker, a quantity of arc extinguishing liquid, an arc chamber immersed in said liquid, separable contacts at least one of which is movable ior establishing an .arc in said arc chamber, operating means for said movable contact, means actuated by said operating means for moving a quantity of arc extinguishing liquid n into engagement with said arc to aid in extinguishing the arc, additional means for moving arc extinguishing liquid into said arc chamber and means for operatively coupling said additional liquid moving means with said contactoperating means at least during the circuit opening movement thereof, said coupling means enabling said contact operating means to move to its full lopen circuit position independently of the additional liquid moving operation. l

2Min a circuit interrupter, a housing containing armextinguishing liquid and having a vent opening, a loxsure member for said opening movable to open and closed positions, separable contacts for establishing an arc within said arc extinguishing liquid, liquid moving means operative to cause a flow ci arc extinguishing liquid in the path between said contacts, resilient means for biasing said closure member to the closed position and for actuating said liquid moving means, and a second liquid moving means rendered operative by said resilient means for moving an additional quantity of arc extinguishing liquid into the path between said contacts.

2\2. In a circuit interrupter, a housing containing arc extinguishing liquid, circuit interrupting means within said housing includng separable contacts, at least one of which is movable for establishing an arc, liquid moving means operative for subjecting the arc path to a-flow of arc extinguishing liquid, pressure relieving means for said housing including a member movable to open and closed positions, single lresilient means for actuating said movable contact and said liquid moving means and for biasing said movable member to the closed position against the pressure Y within said housing, and a second liquid moving means made operative by said resilient means for moving an additional quantity of arc extinguishing liquid into the arc path.

BENJAMIN' P. BAKER. ANDREW H. BAKKEN.