US2364981A

US2364981A - Electric circuit breaker and method of operating the same

Info

Publication number: US2364981A
Application number: US443259A
Authority: US
Inventors: Journeaux Didier
Original assignee: Allis Chalmers Corp
Current assignee: Allis Chalmers Corp
Priority date: 1942-05-16
Filing date: 1942-05-16
Publication date: 1944-12-12
Anticipated expiration: 1961-12-12
Also published as: CH259936A

Description

D. JoURNEAUx Filed may is, 1942 s sheets-sheet 1 AA V" me/NCQ@ ELECTRIC CIRCUIT BREAKER AND METHOD OF OPERATING THE SAME Dec. l2, 1944.

Dec. 12, 1944. D. JouRNEAux ELECTRIC CIRCUIT BREAKER AND METHOD OF OPERATING THE SAME Filed May 16. 1942 3 Sheets-Sheet 2 A D. JOURNEAUX Dec. 12,A 1944.

ELECTRIC CIRCUIT BREAKER AND METHOD OF OPERATING THE SAME Filed May 16, 1942 5 Sheets-Sheet 3 Patented Der-.12, 1944 ELECTRIC CIRCUIT BREAKER AND METHOD F OPERATING THE SAME Didier Journeaux, Wauwatosa, Wis., assigner to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application May 16, 1942, Serial No. 443,259

(Cl. Zim-148) 25 Claims.

This invention relates in general to improvements in electric circuit breakers of the fluid blast type, ,and more particularly to means and a method' of operation for reducing the deterioration of the contacts during opening and closure of the circuit breaker.

Electric circuit breakers of the uid blast type of high current carrying capacity are frequently provided with arcing contacts for opening the circuit, main contacts for .carrying the current when the circuit breaker is closed, and disconnecting contacts for maintaining the circuit open after interruption of the current at the arcing contacts. In such circuit breakers it is advantageous to utilize the pressure oi.' the arc extinguishing fluid to aid in holding thearcing contacts closed while the-main contacts are being opened so as to facilitate the transfer' of current from the main contacts to the arcing contacts. It the opening movement of the contacts takes place in a direction opposite to the direction of the fluid blast,A

however, the contact pressure produced by the air blast must be overcome to open `the arcing contacts. 'I'his disadvantage may be obviated by providing two cooperating movable arcing contacts having different strokes, and opening the contacts are approaching their closed position. and the current of the circuit iiows through an abnormally small contact area from the first engagementv of the disconnecting contacts until the contacts reach ltheir normal closed position. For these reasons the contacts are subject to gradual deterioration. It is therefore advantageous to reopen the arcing contacts prior to closing the disconnecting contacts and to complete the circuit at the arcing contacts, which are designed to operate satisfactorily even when their surfaces have been burned by the arc. The reopening of the arcing`contacts may' be effected with the usual iluid blast provided for arc interruption. The reopening may also be effected in a blast of reduced intensity or in conned uid to reduce the consumption of uid.

It is therefore one of the objects ofthe present invention to provide an improved circuit breaker of the iluid blast type in which the arcing contacts are held closed by the uld blast at the time of separation of Athe main contacts.

Another object of the present invention is to provide an improved circuit breaker o1' the iluid provide a circuit breaker of the iluid blast type tially the ltime o! parting of the main contacts to should be reduced o r even completely stopped as soon as the arc may be assumed to be extinguished. Good operating practice .also requires that disconnecting contacts be opened at that time. It is therefore advantageous to utilize the opening movement oi the disconnecting contacts to control the reduction of the fluid blast after interruption of the arc.

Reclosure of the circuit breaker is generally effected by ilrst reclosing the arclng contacts and thereafter reclosing the disconnecting contacts. An arc may therefore be momentarily established in which the iluid blast in the arcing zone is set in motion substantially simultaneously with the opening of the main contacts and prior to opening of the arcing contacts.

Another object of the present invention is to Aprovide a circuit breakeroi the'uid blastl type in which the duid blast controlled by disconnecting contacts serially connected with the arcing contacts.

Another object of the present invention is to 'provide a circuit-breaker of the' uid blast type in which the circuit is closed as well as opened at companying drawing,in whlchz' between the contacts whilethey u the arcing contacts and is only held open by means or the eilisconnecting contacts.

Another object of the present invention is to provide a method of operating a circuit breaker comprising the steps of closing disconnecting contacts prior to closing the arcing contacts associated therewith. 1

Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the ac- Fig. 1 diagrammatically illustrates, partlyin elevation and partly in `croctsection, a circuit y the arcing chamber taken through line II-II in Fig. 1 showing the main and arcing contacts in closed position and showing the movable disconnecting contact removed from its actual position to illustrate the control of the uid blast by the movable disconnecting contact;

Fig. 3 is a fragmentary view of the arcing chamber illustrated in Fig. 2 showing the main and arcing contacts in fully open position;

Fig. 4 is a top view of movable arcing contact of the embodiment illustrated in Fig. 2;

Fig. 5 is a View similar to Fig. 2 of a modified embodiment of the invention taken partly through a plane parallel to the main plane of .section to illustrate the external air relays controlling the fluid blast;

Fig. 6 is a fragmentary view of the arcing chamber illustrated in Fig. 5 showing the main and arcing contacts in fully open position; and

Fig. 7 is a top view of the movable arcing contact of the'embodiment illustrated in Fig. 5.

Referringmore particularly to the drawings by characters of reference, the circuit breaker illustrated in Fig; 1 comprises a reservoir II constituting a source of arc extinguishing fluid. The fluid may be an inert gas such as nitrogen, but it will be assumed herein that the fluid is compressed air supplied to the reservoir by a suitable compressor (not shown). The current carrying parts of the circuit breaker are supported on reservoir II through a hollow insulator I2 and a post type insulator I3.- Insulator I2 supports a short tubular conductive member I4 provided with a terminal I5 for connecting the circuit breaker in an electric circuit I8. Member I4 supports a hollow insulator I1 containing the main and arcing contacts of the circuit breaker. A conductive cylinder I8 cooperates with insulator I1 to define an arcing chamber I8. Cylinder I8 also contains the actuating mechanism for the main and arcing contacts and is divided into a plurality of parts to rmit machining of its inner working surfaces permit introduction therein of the different movable lelements associated therewith. A movable disconnecting contact 28 is pivoted on cylinder I8 and is' associated with a xeddisconnecting contact 2| mounted on in-V sulator I3 with the second terminal 22 of the circuit breaker.

Insulator I2 provides a connection between res I ervoir II and arcing chamber I8 through a suitable valve 23 for producing a blast of air under pressure between the arcing contacts and through the arcing chamber. Valve 23 may be opened by an air motor 24 of .the spring biased reciprocatory type.' Air under pressure is supplied from reservoir II to motor 24 through a' magnet valve 26. The coil 21 of valve 26 may be energized from a suitable source, such as a battery 28, through a push butto switch 28 and through an auxiliary switch 38 controlled by the circuit breaker. Switch 28 may be connected in parallel with the contacts of a relay 3I. The coil of relay 3l may be energized from a current transformer 32 serially connected with the circuit breaker in circuit I8 to render the opening of the circuit breaker responsive to an op-I erating condition of the circuit. Valve 28.may also control a second air motor 33 for actuating a pressure release valve 34 connected with the arcing chamber through insulator I2.

Contact 28 may be opened by means of an air motor 38 through an insulating rod 31. Motor 38 may be connected with reservoir I I through magnet valve 26. Contact 20 may be reclosed by means of an air motor 38 through rod 31 and through a rocking lever 38. Motor 38 may be connected with reservoir II through a magnet valve 48 having a coil 4I. Valve i0 may be integral'with a stop valve 45 inserted in the conduit joining valve 26 with motor 36 to prevent simultaneous supply of air under pressure to motor 38 and motor 38. Battery 28 may he con- .iected with coil 4I through a second push but- '.on switch 42 and a second auxiliary switch 43. Switch 42 controlsa connection between battery I8 and coil 21 through a third auxiliary switch 44. The three auxiliary switches may be jointly actuated from lever 38 through a connecting rod 46 and a crank 41.

As shown in Fig. 2,v arcing chamber I8 contains cooperating

main contacts

48, 48 and cooperating arcing contacts 50, 5I connected in parallel therewith. The main and arcing contacts are also serially connected with `contacts 20,4 2I through cylinder I8. Contact 48 is divideded into a plurality of segments resiliently mounted on a conductive annular contact holder 52 shaped yas a solid of revolution and bolted or cast in the bore of member I4'so as to extend into the bore Of insulator l1. Holder 52 is bounded by a plurality of surfaces including a plane surface 53 intersecting a concave surface of r `evolution 54. 'I'he segments of contact 48 are arranged adjacent surface 54 and are urged thereagainst by springs 56 so as -to dene substantial- 1y a convex surface of revolution 51. The co-.

operating movable main contact 48 is coaxial with holder 52 and is`bounded by a plurality of surfaces including a plane surface." intersecting a concave surface of revolution 58. Contact 48 is annular and defines an orlce 55.

Contacts

48, 48 are preferably maintained in mutual engagement by means of a.l spring 88.

Contact 48 is mounted on a, sleeve 6I adapted to slide into the bore of cylinder I8. An annular piston 82 mounted on sleeve 8l or on contact 48 cooperates with other elements of the circuit breaker to actuate the sleeve for opening

contacts

48, 48 under the action of the air pressure within the arcing chamber. Piston 82 is arranged within a sleeve 83 extending downward from cylinder I8. The down stroke of sleeve 6I is limited by engagement of contact 48 with support 52 and the up stroke of the sleeve is limited by engagement of an annular thrust member 84 with a step of sleeve 83. The conduction of current between sleeve 8I and cylinder I8 may be eiected through any suitable means such as contact segments 88 arranged in an annular recess 81 of cylinder I8 and urged against the cylinder wall and against sleeve 8l by a garter spring Contact holder 52 containsthe so-called fixed arcing contact 58 which comprises a stem portion 68 guided into a bore of support 52'and carrying a piston 18. The piston is adapted to slide vwithin 'a short cylinder 1I provided in support 52. Contact is resiliently urged into engagement with the cooperating contact 5I by a spring 12 which is relatively weak compared to spring 88. Current is preferably conducted beas shown in Figs. 1 and the adjacent portions oi' contact holder 52. annular shield 14 interposed between

contacts

48 and 58 aids in guiding the air blast between the contacts and shields contact 48 against projection of material separated from contacts 58, by the arc.

The movable arcing contact 5| is a nozzle shaped contact and is provided with shortspokes 18 for mounting the contact in mechanical and conductive connection with contact 49 within orifice 55. Contact 5| thus divides the orice into a central portion and a plurality of seg# mental slots 11. When contacts 58, 5I are closed, they may be considered as dividing arcing chamber I9 into an inlet chamber 18 having its inlet defined by member I4 and holder 52, and an outlet chamber 19. The outlet chamber extends upward from contact 5| through cylinder |8 to suitable outlet means 88 provided on the cylinder. Slots 11 form a, path for the ilow of air from the inlet chamber into the outlet chamber independently of the opening of contacts 58. 5I. The ilow of air through slots 11, however, depends on the position of contact 49 which cooperates with contact holder 52 to form valve means controllirg the flow of air through the slots and also c'onytrolling the admission of air from the inlet chamber to the engaging surfaces of contacts` 58, 5|.

Outletchamber 19 contains a bent electrode 8| extending through the wall of cylinder |8through' an insulating bushing 82 and 'connected with:

member I4 through a suitable resistor 83. trode 8| is preferably Elecsurrounded by a plurality of coaxial metallic baffles 84 connected therewith and serving to cool and deionize the air blast passing through the arcing chamber. An insulating sleeve 86 is inserted within cylinder I8 and sleeve 8| and about electrode 8| and bailles 84 to prevent fiashovers therebetween. A shield 81 mounted on sleeve 6I prevents deposition on the lower part of sleeve 88 of material separated from the arcing contactsby the arc.

Bales 88 may be arrangedwithin passages 85 leading from outlets 88 to atmosphere to assist -bailles 84 in cooling the air blast and to prevent accidental introduction of foreign material into the circuit breaker. Check valves 89 may be further provided to prevent circulation of dust or snow laden air from one outlet to the other through the arcing chamber.

Cutlets 88 are, controlled by suitable valve means such as a balanced poppet valve 98. The valve is normally maintained open by a spring 9| and may be actuated by a piston 92 adapted to slide within a cylinder 93. When valve 98 is closed, the air flow through arcing chamber I9 may be completely interrupted, or additional outlets 94 may be provided to dene a path for a reduced blast of air \suftlcient 'to maintain the arcing contacts open and to prevent reignition' of the arc. g

Cylinder 93 may be supplied with air under pressure from inlet chamber 18 through a port 98, an air relay 91 and a conduit 98. The piston 99 of relay 91 is urged toward the-right by the air pressure transmitted from the inlet chamber. When contact 2 8 is closed. movement of piston 99 to admit air under pressure to cylinder 93 is prevented by an adjustable stop |88 provided on contact 28.

ycontacts 88, cylinder I8, and contacts 28, 2|.

current transformer 32. Battery I8 is therebyv connected with coil 21 through switch 38, and the coil actuates valve 28. Air under pressure is admitted from reservoir through valve 28 to

motors

24, 33 and 38. I'he three motors are suitably dimensioned to insure their operation in the desired sequence at the desired time intervals. Motor 33 may operate at the same time as motor 93 or immediately thereafter to open Valve 23. Air under pressure vis admitted from reservoir II through valve 23 into insulator I2, member I4, and inlet chamber 18. Air applied to the lower faces of

pistons

82 and 18, the upper faces of which are subjected to atmospheric pressure. 'I'he air pressure on piston 18 cooperates with spring 12 to urge contact 58 against contact 5I, thereby holding the contacts closed under a greatly increased pressure, imparting to

contacts

49, 58, 5I a joint initial acceleration. 'I'he air pressure on piston 82 also accelerates

contacts

49, 5| and sleeve 8| without materially lessening the contact pressure of

contacts

58, 5| because the inertia of contacts 49, 5I and sleeve 8| is much greater than that of contact 58, stem 69 and piston 18.

Until the contacts begin to move, contact holder 52 and contact 49 cooperate to prevent the access Aof air from inlet chamber 18 into outlet charnber 19 through slots 11. Air pressure is also thereby withheld from the engaging surfaces of contacts 58, 5I where such pressure would tend to open

contacts

58, 5| prematurely in circuit breakers where stem 69 has a. greater diameter than the circle along which

contacts

58, 5| are in engagement.

Upward movement of the main and arcing contacts 'first causes contact 49 to disengage contact holder 52. Air under pressure is then admitted to the lower face of contact 49 and assists the lupward movement of the contact. Air then may also flow into outlet chamber 19 through slots 11, thereby setting in motion the air column con- Upward movement of contact 58 is stopped by abutment of piston 18 against the end wall of cylinder 1I. Contact 58 is then in the position shown in Fig. 3 and

contacts

48, 49 are then open a predetermined extent. Contacts-49 and :I thereupon continue their upward movement o tioned predetermined extent under the action of the impulse imparted thereto byv piston 18 and of the continued application of air pressure on the lower faces of piston` 82 and of contacts 49,

pressure is therebyv

open contacts

48, 49 beyondY the above men-v 5|. Continued movement of contact 5| causes contact 5| to disengage contact 50. An arc is drawn therebetween and at the same time the air blast initiated through slots 11 is supplemented by the blast through the bore of contact 5|.

Contacts

49, 5| ultimately reach the fully open position shown in Fig. 3 to establish a gap between

contacts

50, 5| of such width as to result in the most efficient arc extinguishing action of the air blast therethrough. It will be observed that the movement of

contacts

49, 5| takes place in the direction of the air blast flowing through the nozzle portion of contact 49 so that

y'contacts

50, 5| may be at rst held in engagement and thereafter separated without reversal of the application of air pressure to contact 5|. l

The air blast causes one of the roots of the arc drawn between

contacts

50, 5| to travel on contact 50 towards the center of its arc carrying surface. The other root of the arc travels along the bore of contact 5l and is thus always maintained within the contour of the air blast directed through contact 5l and through slots 11 so that no portion of the arc is outside thepair blast. The air blast also causes the arc to be looped between the contacts through the bore of contact 5| into chamber 19. The portion of the blast established through slots 11, which is substantially annular, directs the arc. toward the axis of chamber 19 and diverts material detached from the arcing contacts by the arc away from shield 81 and sleeve 86. The arc ultimately reaches the tip of electrode 8| and thereupon breaks into two portions. One arc portion extending between contact 50 and electrode 8| is connected in parallel with resistor 83 and extinguishes toward the rst half cycle of arcing. The second arc portion extending between contact -5| and electrode 8| is connected in series with resistor 83 and therefore carries a relatively low current at high power factor, so that it is readily extinguished by the air blast. The air blast also prevents reignition of the arc as is well known.

During the above described operation, air under pressure is admitted from chamber 18 and into relay 91, but operation of the relay is initially prevented by stop |00. Air is also admitted from vreservoir through valve 26 to motor 36, and the operation of motor 36- is so adjusted that contact 20 disengages contact 2| immediately after the arc drawn between

contacts

50, 5| may be assumed to be extinguished. Disengaging movement of contact 20 causes movement of stop |00, thereby enabling the air pressure on the left side of piston 99 to move the piston to the right to connect cylinder 93 with chamber 18. The air pressure on the left side of piston 92 causes the piston to move to the right against the action of spring 9| and valve 90 closes orifices 80. v

Theow of air through the circuit breaker is then stopped or continues at a reduced rate through outlets 94 to cause the dielectric strength ofthe' gap between the main and areing contacts to remain suillcient to prevent reignition of the arcwith a minimum consumption of compressed air. When contact 20 reaches its fully open position, the air gap between contacts 20 and 2| is sufllcient to maintain circuit I8 open and contacts, 49, 50 and/5| may be reclosed.

'When contact 20 is substantially fully opened,

switch 30 disconnects coil 21 from battery 28,

.and valve 29 recloses. Motor 36 then stops to the same time switch 44 opens aaeaasi maintain contact 20 open. Valve 23 is reclosed by the spring of motorl 24 and valve 34 is reopened by the spring of motor 33. The arcing chamber is rapidly emptied of air under pressure through valve 34 and the main and arcing contacts are reclosed by spring 60 while valve 93 is opened by 'spring 9|.

During return of the main and' arcing contacts to the position shown in Fig. 2, the axial movement of contact 49 relative to contact 48 and contact holder 52 causes sequential sliding engagement of contact 49 with the convex surface defined by the segments of contact 48 and abutting engagement of

surfaces

53 and 58 to stop contact 49.

The circuit breaker may be reclosed by closing switch 42. The switch connects coil 4| with battery 28 through switch 43, which is then closed. Coil 4| actuates valve 40, which admits air under pressure Vfrom reservoir to motor 38 to cause the motor to return contact 20 towards the closed position shown. Valve 45 is also actuated to disconnect motor 36 from valve 2G. At a predetermined point of the reclosing stroke of contact 20, switch 44 connects battery 28 with coil 21. Coil 21 actuates valve 26, causing valve to close and valve 23 to open to admit air from reservoir to inner chamber 18. Contact 2t* then still being open, stop |00 is disengaged from `piston 99 and air under pressure is 4admitted through relay 91 to cylinder 93 to cause immediate closure of valve 90. The 'air pressure within chamber 18 causes sequential opening of

contacts

48, 49 and of

contacts

50, 5| in the manner above described. The entire arcing chamber is then filled with air under pressure which is confined within the chamber or allowed to flow at a relatively low rate through orifices 84 so as to hold the contacts open.

Continued movement of contact 20 causes stop |00 to return to the position shown. Upon substantial completion of the closing movement of contact 20, piston 99 is moved by stop |00 to discharge the air contained in cylinder 93 to atmosphere. Spring 9| thereupon returns valve to the open position shown. Substantially at to disconnect coil 21 from battery 28. Valve 26 returns to the position shown to cause valve 23 to reclose and valve 34 to reopen. Valves 34 and 90 release the air confined within chamber I9, thereby enabling spring 60 to sequentially reclose the arcing contacts and the main contacts. Circuit I8 is reclosed by reengagement of the arcing contacts, but any arcing that may take place between the arcing contacts .prior to their reengagement or any local overheating due to insuicient contact area are without detrimental effect as the current is diverted from the arcing contacts as soon as the main vcontacts close. The circuit breaker thereupon is ready to reopen immediately if the flow of current through circuit IB is of excessive magnitude.

In the embodiment illustrated in Fig. 5, the segments of xed Contact 49 are mounted on an annular projection |0| of member |4 linstead of on contact holder 52, to engage the convex outer surface of contact 49. An annular shield |02 is mounted on sleeve 44 between the arcing surfaces of

contacts

50, 5| and the engaging surfaces of

contacts

48, 49 to prevent deposition on the main contacts of material separated from the arcing contacts by the arc.

'I'he bore of contact 5| is provided with a plu rality of longitudinal ribs |83, the lower ends of vpaths for the travel ofone root of the arc within the contour of the air blast. A

In the present embodiment contact 50 is generally disengaged from contact I under the action of gravity and of a spring |04. Stem 69 projects through `piston and is attached to the hollow stem |06 of a poppet valve |01 having its seat at the lower end of member, I4. Valve stem |06 isguided in a sleeve |08 integral with a suitably shaped cylinder head |09 mounted on cylinder 1|. Stem |06 is provided with ports IIII cooperating with ports III of sleeve |03 to control the admission of air into cylinder 1 I. The air pressure within cylinder 1I,i may further be controlled by a pressure responsive valve I|2 of any suitable type acting with an adjustable time delay. Valve I|2 may comprise a piston I I3 subjected to the action of the pressure within cylinder 1I through a needle valve II4. Piston IIB acts against a spring I I6 to cause a second piston I I1 to connect cylinder 1| with atmosphere.

Valve 90 consists of a pair of unbalanced butteriiy members which are interlinked through a pair of cranks I I8 and a connecting rod I I9. The valve members are so disposed Within outlets 80 -as to be closed by the air blast through the outlets and are otherwise maintained open by spring 9| in a position determined by abutment of a crank II8 with a stop |20. The closure of valve 90 is controlled by latch |2I.actuated by an air motor |25 connected with the arcing chamber through conduit 98, relay 91 and port 96. Relay 91 is provided with a second piston |22 controlling a conduit |23. The position of the pistons is controlled by stop |00 and by a spring |24.

The operation of the present embodiment is generally similar to that of the embodiment illustrated in Fig. 2 except as hereinafter specifically set forth.

When the circuit breaker is to be opened, valve 23 is caused to open as above described. Valve |01 being initially closed, the air pressure is momentarily withheld from contacts 49, 5I and piston 62. The air pressure acts on the lower face of valve |01 and, through stem |06 and ports I I0, II I, on the lower face of piston 10. The air pressure thus applied causes impact of contact 50 against contact 5I to impart an initial acceleration thereto and to hold the contacts closed under high pressure until opening of the main contacts. Valve I 01 also opens to admit air under pressure to the lower face of contact 5I and to shield |02 to assist in moving sleeve 6I with

contacts

49, 5| and to cause opening of

contacts

48, 49. Movement of contact 49 admits air under pressure through slots 11 into chamber 19. Airis also admitted to the lower` face of piston 62'to complete the movement of the con tacts and to cause opening of contacts 50, `5I

I' against the action of spring 60. The air blast established between the contacts extinguishes the arc as above described.

Upon opening movement of contact 49, air under pressure is admitted from the arcing chamber through port 96, relay 91 and conduit |23 to the left side of piston |21. Piston |21 moves piston |28 to the right against the action of spring |29. Upon opening movement of contact 20, spring |24 moves pistons |22 and 99 to the right at a rate determined by the movement of stop |00. Piston |22 closes conduit |23 and piston 99 substantially simultaneously therewith connects conduit 98 with port 96. Air under pressure is then admitted from the arcingchamber to motor |25 through port 96, relay 91, conduit 98 and relay |26. Latch I2| is withdrawn by the motor to release valve 90, which is closed by the blast then established through outlets 80. Upon further opening of contact 20, piston |22 connects conduit |23 with atmosphere, and spring |29 returns pistons |21, |28 to the position shown. Motor |25 is thereby connected to atmosphere and returns latch I2I to the position shown.

When valve 23 is reclosed and valve 34 is reopened,. the release of the air pressure from arcing chamber I9 enables valve 90 to return to the open position shown and to reengage latch I2I.

Contacts

49, 5| are moved downward by spring 60 until engagement of contact 5| with contact 50. At that moment air under pressure is conned within the cylinder 1I because ports |I0 are out of registration with ports III when contact 50 is at the top of its stroke. At rst the air pressure Within cylinder 1I holds contact 50 in its top position and prevents reclosure of

contacts

48, 49. Air under pressure is, however, admitted slowly from cylinder 1| through valve |I4 to the right side of piston H3. After a predetermined time delay the airpressure on piston I I3 overcomes the action of spring I I 6 and causes pistons I I3, lI'l to move to the left. Piston II1 connects cylinder 1| with atmosphere to enable

contacts

49, 50 and 5| to return to the position shown in Fig. 5.

When the circuit breaker is to be reclosed, air under pressure is admitted first to motor 26 and afterwards momentarily to

motors

24, 33 in the manner above described. Air under pressure is then again admitted to the arcing chamber to cause

contacts

48, 49, 50 and 5| to open before contact 20 closes. While contact 20 is still open, piston |22 connects conduit I 23 to atmosphere and relay |26 remains in the position shown. Air under pressure is not admitted to-motor |25 and valve is held open by latch I2 I.

During completion of the closing movement of contact 20, pistons 99, |23 are gradually returned by stop |00 to the position shown. Piston 99 rst disconnects conduit 98 from port 96 and piston |22 thereafter connects conduit |23 with port 96. Pistons |21, |28 are thereby caused to move to the right as above described, but the connection between motor |25 and the `arcing chamber remains interrupted by piston 99 so that latch |2| `ls not withdrawn. Substantially'at the time of rent through circuit I6 is reestablished upon rereopening of the circuit breaker `the excessively high current is carried only by the'arcing contacts, thereby reducing the danger of damage to the main contacts.

Although but two embodiments of the present invention have been illustrated and described, it willbe apparent to those skilled in the art that various modifications and changes may be made therein without departing from the spirit of the.

invention or-` from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent: l

- 1. An electric circuit breaker comprising cooperating arcing contacts, cooperating main contacts connected in parallel with said arcing contacts, means operable by iiuid under pressure acting on one of said arcing contacts for simultaneously actuating said arcing contacts and one of said main contacts to maintain said arcing contacts closed under pressure while opening said main contacts a predetermined extent, and means operable by fluid under pressure for continuing the action of the other one of said arcing contacts and of said one of said main contacts for opening said arcing contacts and for opening said main contacts beyond said predetermined extent. 2. An electric circuit breaker comprising cooperating stationary and movable main contacts,

. an arcing contact connectedv with said stationary said arcing contactsl closedunder pressure untill separation of said main contacts.

3. An electric circuit breaker comprising cooperating stationary and movable main contacts. an arcing contact connected with said stationary main contact and mounted in saidcircuit breaker i'or movement within predetermined limits, a movable arcing contact in mechanical and conductive connection with said movable main contact, resilient meansv urging the rst said arcing contact into engagement with said movable arcing contact during movement of the iirst said arcing contact within said predetermined limits, means operable by fluid under pressure acting on said main and arcing movable contacts for opening said main. contacts and for thereafter opening said arcing contacts, and meansoperable by fluid under pressure acting on the first said arcing contact during operation of the irst said means for increasing the contact pressure of said arcing contacts from the beginning of the opening operation of said main contacts until separation of said arcing contacts.

4. An electric circuit breaker comprising cooperating stationary and movable main contacts, a movable arcing contact in mechanical and conductive connectioniwith said movable main contact, an arcing contact mountedl in the circuit breaker for limited movement causing said arcing contacts to open when said main contacts are closed, means Aoperable by uid under pressure acting on the second said arcing contact to cause impact of the second said arcing contact on said movable arcing contact to actuate said movable main and arcing contacts and cause separation of said main contacts with transfer of the current from said main contacts to said arcing contacts, and means operable by uid under pressure for further actuating said movable contacts to open said arcing contacts.

5. An electric circuit breaker comprising an arcing chamber, a pair of cooperating arcing contacts arranged in said chamber, cooperating iixed and movable main contacts arranged in said chamber and connected in parallel with said arcing contacts, means for directing a blast of arc extinguishing iiuid through said chamber, and means for sequentially opening'said main and arcing contacts comprising means operable by fluid under pressure for moving one of said arcing contacts in the direction o! said blast a predetermined extent, and means distinct from the iirst said contact moving means operable by fluid under pressure for moving the other one of said arcing contacts and said movable main contact in the direction of said blast an extent greater than said predetermined extent.

6. In combination, an electric circuit. a circuit breaker comprising cooperating arcing contacts, cooperating disconnecting contacts serially connected with said arcing contacts in said circuit, main contacts connected in parallel with said arcing contacts, means for causing opening of said main and arcing contacts comprising means operable by iiuid under pressure for simultaneously actuating said arcing contacts and one of said main contacts to impart a joint initial acceleration thereto, means operable by iiuid under pressure for continuing the actuation of only one of said arcing contacts and of said one of said main contacts to cause sequential opening of said main contacts and of said arcing contacts, means operable by iluid under pressure for opening said disconnecting contacts while said arcing contacts are open, and means comprising a source of fluid under pressure for controlling the operation of said contact opening means.

7. An electric circuit breaker comprising an arcing chamber having an inlet, a pair of cooper'- ating arcing contacts arranged to divide said chamber into an inlet portion and an outlet portion, a pair of cooperating main contacts connected in parallel with said arcing contacts, means for introducing arc iiuid under pressure into said chamber through said inlet, means for opening said main contacts and for admitting said huid from said inlet to the engaging surfaces oi' said arcing contacts, and means for opening said arcing contacts to draw an 'arc therebetween andtn thereby establish a path for a blast of said fluid from said inlet por tion to said outlet portion between said contacts to extinguish the arc.

8. An electric circuit breaker comprising an arcing chamber having an inlet and an outlet, a

pair ofcooperating arcing contacts arranged to divide said chamber into an inlet portion and an outlet portion, a pair of cooperating main contacts connected in parallel with said arcing contacts. means for introducing arc extinguishing iiuid under pressure into said inlet portion, means forming a path for the now of said iluid from said inlet portion into said outlet portion independently of opening of said arcing contacts. valve means comprising one of said main for controlling said path, and common means for sequentially opening said valve means to initiate the ilow of said iluid from said inlet portion into said outlet portion; opening said main contacts, and opening said arcing contacts to draw an arc therebetween and to thereby establish a path for a blast of said fluid from said inlet portion to said outlet portion between said contacts to extinguish the arc.

9. An electric circuit breaker comprising an arcing chamber having an inlet and an outlet, a pair of cooperating arcing contacts arranged to divide said chamber into an inlet portion and an outlet portion, means for introducing arc extinguishing fluid under pressure into said inlet portion, means forming a path for the ilow of said fluid from said inlet portion into said outlet portion, a iirst valve meansv for controlling said path, a second valve means for controlling said outlet, means for opening said first valve means to initiate the ilow of said fluid from said inlet portion into said outlet portion, means for thereafter opening said contacts' to draw an arc therebetween and to cause a blast of said iluid between said contacts to extinguish the arc, and means for causing. operation of the second said valve means after extinction of the arc to reduce the blast of fluid between said contacts and main- ,tain said chamber under pressure to prevent o contacts to prevent deposition'on said main contacts of material separated from said arcing contacts by the arc.

11. An electric circuitbreaker comprising an annular conductive member bounded by a plane surface intersecting a concave surface of revolution, a plurality of contact segments arranged adjacent said concave surface of revolution to define substantially a convex surface of revolution, means for resiliently mounting said contacts on said member and for urging said segments against said concave surface of revolution, a contact coaxial with said member bounded by a second plane surface intersecting a second concave surface of revolution, and means for causing relative axial movement of said member and of said contact to cause sequential sliding engagement of said contact with the convex surface of said segments and abutting engagement of said plane surfaces.

12. An electric circuit breaker comprising cooperatingarcing contacts, cooperating main contacts connected in parallel with said arcing contacts, a source of arcextinguishing fluid under pressure, means operable by iiuid under pressure for opening said main contacts, means operable by fluid under pressure for opening said arcing contacts, and means responsive to the operation of the second said contact opening means for controlling the supply of uid from said source to the iirst said contact opening means.

13. An electric circuit breaker comprising an arcing chamber having an outlet, a pair of cooperating arcing contacts arranged in said chamber, means for opening said contacts, means for producing a blast of arc extinguishing uid directed between said contacts and through said chamber, valve means for controlling said outlet, a pair' of `cooperating disconnecting contacts serially connected with said arcing contacts, one of said disconnecting contacts being movable, and means responsive to *no lement of said movable disconnecting contact for controlling the operation of said valve means.

14. An electric circuit breakercomprising an arcing chamber having an outlet, a pair of cooperating arcing contacts arranged in said chamber, means for opening said contacts, means for producing a blast of arc extinguishing fluid directed between said contacts and through said chamber, valve means for controlling said outlet, a pair of cooperating disconnecting contacts serially connected with said arcing contacts, means for opening said disconnecting contacts, and means responsive to the operation of said disconnecting contact opening means for causing operation of said valve means.

15. An electric circuit breaker comprising an arcing chamber having an outlet, a'pair of co-- operating arcing contacts arranged in said cham- Y ber. means for opening said contacts, means for producing a blast of arc extinguishing fluid directed between said contacts and through said chamber, valve means for controlling said outlet. a pair of cooperating disconnecting contacts serially connected with said arcing contacts, means for opening said disconnecting contacts, means operable by iiuid under pressure for closing said valve means, and means responsive to opening of said disconnecting contacts for connecting said valve closing means with said arcing chamber.

` 16. An velectric circuitbreaker comprising an arcing chamber having an outlet, a pair of cooperating arcing contacts arranged in said chamber, means for opening lsaid contacts, means for producing a blast of arc extinguishing fluid directed between said contacts and through said chamber, valve means for controlling said outlet, a pair of cooperating disconnecting contacts serially connected with said arcing contacts, means for opening said disconnecting contacts, means operable by uid under pressure from said chamber for closing said valve means, and means responsive to pressure within said chamber and to opening of said disconnecting contacts for controlling the operation of said valve closing means.

17. An electric circuit breaker comprising an arcing chamber, a pair of cooperating arcing contacts arranged in said chamber, a pair of cooperating disconnecting contacts serially connected with said arcing contacts, means for closing said disconnecting contacts, means responsive to closing movement of said disconnecting contacts for illling said chamber with arc extinguishing iiuid under pressure and for opening said arcing contacts, and means responsive to substantial completion oi the closing movement of said disconnecting contacts for releasing the uid contained within said chamber and for reclosing said arcing contacts. y

18. An electric circuit breaker comprising an arcing chamber,- a pair of 'cooperating arcing contacts arranged in said chamber, a pair of cooperating disconnecting contacts serially connected with said arcing contacts, means for closing said disconnecting contacts, means responsive to closing movein of said disconnecting contacts for opening arcing contacts and for directing a blast of arc extinguishing uid between said contacts and through said chamber, and means responsive to substantial completion of the closing movement of said disconnecting contacts for reclosing said arcing contacts and interrupting said fluid blast.

19. An electric circuit breaker -comprising an arcing chamber, a pair oi' cooperating arcing contacts arranged in said chamber, one of said contacts being an annular contact, means for opening said contacts to draw an arc therebetween, means for directing a blast of arc extinguishing fluid through said chamber, between said contacts and through said annular contact, said annular contactI comprising a. nozzle shaped portion forming a path for'one of the roots of the arc wholly within the contour of said blast.

20. An electric circuit breaker comprising a I pair of cooperating arcing contacts, a pair of cooperating disconnecting contacts serially connected with said arcing contacts, means for opening said arcing contacts', means for closing said disconnecting contacts, means for reclosing said arcing contacts, and means for causing sequential operation of the rst, second andthird said means in the order recited.

21. The method of effecting a normal circuit closing operation of a circuit breaker comprising arcing contacts serially connected with disconnecting contacts in the circuit comprising the steps of opening the arcing contacts, closing the disconnecting contacts, and reclosing the arcing contacts to complete the circuit.

22. An electric circuit breaker comprising a pair of cooperating arcing contacts, a pair of cooperating main contacts connected in parallel with said arcing contacts, a pair of disconnecting contacts serially connected with said arcing and main contacts, means for opening said main contacts, means for opening said arcing contacts, means for closing said disconnecting contacts, means for reclosing said arcing contacts, means for reclosing said main contacts, and

means for causing sequential operation of the diii'erent said means in the order recited.

23. The method ot closing an electric circuit comprising the steps of opening a pair of main contacts connected in the circuit, opening a pair of arcing contacts connected' in parallel with the main contacts. closing a pair of disconnecting contacts serially connected with the main and arcing contacts, reclosing the arcing contacts and reclosing the main contacts. f

24. An electric circuit breaker comprising a pair of cooperating arcing contacts, a pair of cooperating main contacts connected in parallei with said arcing contacts, means for opening said main and arcing contacts, means for reclosing said arcing contacts, and time delay means for reclosing said main contacts after reclosure of said arcing contacts. l

25. An electric circuit breaker comprising a pair of cooperating arcing contacts, a pair oi' cooperating main contacts connected in parallel with said arcing contacts, a source of arc extinguishing uid under pressure, a nozzle unitary with one of said main contacts, said nome being closed by one of said arcing contacts when said arcing contacts are closed, means for causing movement of one of said main contacts and one of said arcing contacts to open said main contacts and thereafter to open said arcing contacts to draw an arc therebetween, said contacts dening a path for the flow of uid from said source through said nozzle to extinguish the arc, the said movements of said contacts being in the direction of the said ow of iuid through said nozzle.

DIDIER J OURNEAUX.