US2287039A - Electric circuit breaker - Google Patents

Description

June 23, 1942.

a. E. .gmssou ELECTRIC CIRCUIT BREAKER 4 Sheets-Sheet 1 Filed June 10, 1940 June 23, 1942.

G. E. JANSSON ELECTRIC CIRCUIT BREAKER Filed June 10, 1940 4 Sheets-Sheet 3 breaker.

should be so shaped as to define a nozzle gradually converging toward the arcing surfaces of.

Patented June 23, 1942 ELECTRIC CIRCUIT BREAKER,

Gustav E. Jansson, North Quincy, Mass, assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application June 10, 1940, Serial No. 339,598

16 Claims. (01. 200-148) to interrupt relatively large currents in a very.

short length of time. To obtain a fast interrupting operationthe movable elements of they circuit breaker are generally made as light as possible, sometimes providingonly abutting arcing contacts for the flow of current through the circuit breaker. These contacts become burnt during current interrupting operation of the circuit breaker and accordingly may offer a relatively high resistance to the flow of current therethrough.

It is therefore desirable to provide main or current carrying contacts in parallel with the arcing contacts and to mount the movable main contact resiliently on the movable arcing contact. In this manner the two sets of'contacts may be sequentially operated by common actuaiing means without excessive increase in the weight of the movable members of the circuit The arcing chamber and the. contacts the arcing contacts.

increases to a maximum value as the fluid progresses towards the arcing contacts. Another object of the present invention is to I provide a circuit breaker of the fluid blast type in With this arrangement the air blast rapidly transfers the are from the. arcing contacts to arcing electrodes provided therefor, thereby re-' ducing the burning at the arcing contacts. Material vaporized from the arcing contacts isalso driven away from the main contacts which are thus protected against deterioraiionf The are is preferably directed against nested baflles associated with an electrode connected with one of the contacts through a resistor to shunt a portion of the arc andthereby tocause its extinction.

It is therefore one of the objects of the present inven ion to provide a circuit breakerof the fluid'blast type in which current is normally conducted by contacts other than the contacts at which the current is interrupted.

Another object of"'the present invention is to I provide a circuit breaker of the fluid blast type facilitating the transfer of current from the main contacts to the'arcing contacts. l

Another object of the present invention is to shown in the closed position; and

which the arc is extinguished by the combinedaction 'of nested baifles and of a resistive shunt.

Objects and advantages other than those above set forthwill be apparent from the following description when read in connection companying drawings, in which:

Fig. 1 is a view partly in elevation and partly in cross section of one embodiment of the present invention comprising a horizontally disposed arcing chamber;

Fig.2 is an axial cross section through the arcing chamber of the embodiment illustrated in Fig. 1 showing the main and arcing contacts of the circuit breaker'in the closed position; I

Fig. 3 is a view similar to Fig. .2 showing the contacts in the open position; I

Fig. 4 is an end view of the movable arcing contact of the embodiment illustrated in Fig. 1;

Fig. 5 is an end view of the stationary main and arcing contact assembly of the embodiment illustrated in Fig. 1; a

Fig. 6 is a partial cross section through-a modiflcation of the arc extinguishing-chamber of the embodiment illustrated in Fig. 1; I Fig. 7 is aview in side elevation of a odifled embodiment of the present invention co prising a vertically disposed arcing chamber;

Fig. 8 is an axial cross section through the arcing chamber and the'arc chamber of the embodiment illustrated in Fig. "l showing the imaln' and arcing contacts of the circuit breaker in the open position;

Fig. 9 is an axial cross section through the arcing chamber of another modified embodiment of the presentinvention in which. the main contacts are disposed outside of the arcing chamber, all the contacts of the circuit breaker being Fig. 10 is a view similar to Pie-9 showi g all the contacts of the circuit breaker in the open position.

Elements performing the same function in these different embodiments are designated therein by the same reference character although such elements may be of different configuration in the diflerent embodiments shown.

Referring more particularly to the drawings by characters of reference, reference numeral H desig nates'a reservoir serving both as structural element and assource of supply of fluid under pressure ior-the circuit breaker. The fluid utir with the ac- 2 lized may be any of the insulating fluids suitable for extinguishing arcs but will be assumed to be compressed air preferably maintained at a pressure of the order of 135 to 215 pounds per square inch. Reservoir Il may be placed in communication with a hollow cylinder l2 defining an arcingchamber l3 through a valve 14 and through a hollow insulator |6.. The flow of fluid from reservoir II to atmosphere continues from arcing chamber I3 through an orifice I1 of the arcing chamber and through an arc extinguishing chamber 13. Chamber [8 is generally defined by an elbow 19 of conductive material having a substantiallyuniform cross section and by a cylinder 20 of insulating material.

Valve I4 is preferably operated by means of a pneumatic motor 2| adapted-to be supplied with air from reservoir ll through a valve 22 controlled by a solenoid 23. When valve 14 is open air is also supplied therethrough to a second air' motor 24 serving to open a movable disconnect ing contact 26 cooperating with a fixed disconductors 3| which are joined through disconnecting contacts '26, 21 in series with the main and arcing contacts of the circuit breaker.

As illustrated in Figs. 2 and 3 the arcing chamber is provided with'a pair of cooperating main contacts 32, 33. .Contact 32 is a fixed an-- nular contact comprising a, plurality of. segments resiliently mounted on a'conductive annular contact support 34; Support 34 is bounded by a piu-' rality'v of intersecting surfaces including a plane surface36 and a cylindrical surface 31. The segments ofcontact 32 are arranged about cylindrito close orifice 11. Contact 5| is an annular fixed contact arranged about orifice l1 coaxially with contact 32 and connected therewith through support 34. Contact 52 is mounted on a stud 53 slidably supported within piston rod 44. A spring 54 arranged between contact 33 and alock nut 56 screwed on stud 53 tends to separate contacts 33 and 52 to an extent limited by a stop 51. Contact 52 is thus resiliently supported on contact 33 and piston 46 serves as common means for sequentially separating contacts 32, 33 and contacts 5|, 52'.

Relatively movable contacts 33, 52 are connected by a plurality of flexible conductors 58 reinforced and -joined at both ends by riveted washers 59. Spring 54, which maintains contacts 33;

52 in predetermined relative position, acts on the contacts through the end portions of conductors 58 to clamp the conductors against the contacts of the arc to the arcing electrode the portion of the arcing chamber adjacent the cooperating surfaces of contacts 51, 52 is arranged to form a gradually converging nozzle by proper dimensioning of the arcing chamberv and of the main and arcing contacts and by suitable positioning cal'surface 31 to define a concave contact surface the cooperating surfaces of the arcing contacts of revolution 38 for resilient sliding engagement of contact 33 with contact 32. The contact segments are pivotally mounted on support 34 and are resiliently urged against cylindrical surface 31 by springs 39 held by screws 46. An insulating of the contacts within the chamber. The path for the flow'of compressed air from reservoir II to atmosphere comprises this nozzle, which has preferably its smallest cross section defined by regardless of the extent of opening of the contacts. Even when contacts 5|, 52-are fully open,

liner 4| prevents screws. 46 from working loose axial with contact 32 and is bounded by .a plurality' of intersectingsurfaces including a plane surface '42 and a cylindrical surface 43. Contact 33 is provided with an extension 44 forming a hollow piston rod rigidly connected with a piston 46 carrying contact 21. Piston 46 is arranged for reciprocatory movement within 'a cylinder 41 communicating with arcing chamber 13 and mounted on cylinder [2 through an insulating bushing 48. A spring 49 moves contact 33 toward contact 32 to cause sequential sliding engagement'of surface 43 with surface 33 and abutting engagement of surface 42 with surface 36. The movement of contact 33 into the closed p0- sltion thereof is thus limited independently of the fixed main and arcing contacts of the circuit I breaker. Contacts 32, 33 are adapted to be separated by means of piston 46 under the action of the air pressure withinthe arcing chamber and cylinder 41. The air, pressure exerted on contact 33 in the closing direction thereof is balanced by admitting air within contact 33 from chamber l3 through apertures 50.

' ranged within the arcing chamber and operable '-in chamber the cross-section area of the passage defined by their cooperating surfaces is preferably smaller than the cross-section area of aperture l1.

A second arcing electrode 62 is arranged withsubstantially axially thereof. Electrode .62 is supported on a pair -of conductive spiders 63 mounted on insulating cylinder 26 and is connected with contact 33,,through a resistor 64 and through a conductor 65 comprising a flexible port-ion. As more clearly illustrated inFZ'g. 8 resistor 64 consists of two parallel wires of suitable resistive material wound in two layers on cylinder 20. These two wires are wound in opposite directions so as to render the resistor substantially non-inductive. A shield 66 is arranged adjacent a portion of the'surface of cylinder 20 to prevent deposition of material'vaporiz'ed from contacts 5|, 52 on the shielded portion of cylinder 20. In this manner a conductive rathcannot be established between electrode 62 as illustrated in Figs. 1 and 2, current flows between conductors 3| through the wall of cylinder 12, main contacts 32, 33 and disconnecting contacts 21, 26. Although the arcing contacts are The air blast issuing from the arcing chamber between contacts 5| and 52 drives the arc toward chamber IS. The root of the are on contact 52 is displacedon the surface of the contact until it is transferred to arcing electrode 5| The other root of the are on contact 5| moves along the bore of contact 5| and on the inner surface of elbow l9 until it is prevented from progressing further by shield 55. The are also gradually lengthens as its roots are displaced. The portion of the are attached to electrode 5| is guided tofrom reservoir through valve H to arcing chamber l3 and to motor 24. While the air pressure within the arcing chamber builds up to the pressure of reservoir H air is leaking through apertures 50 and past contacts 5|, 52 through grooves 60, thereby giving an initial acceleration to the air column contained within the arc interrupting chamber.

When the air pressure within the arcing chamber and within cylinder 41 reaches a suflicient value, piston 46 is moved toward the right against the action of spring 49. Movement of piston 46 first separates main contacts 32,.33

- in temperature.

while spring 54 maintains arcing contact 52 applied against contact 5|. Upon separation of the main contacts the flow of current is diverted from the main contacts to the arcing'eontacts against the action of the resistive voltage drop I in the arcing contacts andv against an inductive voltage due to the rate of change of the fiow of current through the connections between the main and arcing contacts. The relative posi-.

tioning of the main and arcing contacts in eo- 3 axial .relation limits the inductance of the connections therebetween to an extremely low value wards the axis of chamber I8 by the air blast,

which is radial between electrodes 5| and 52.

The are therefore rapidly comes "in contact with electrode 62, whereupon it breaks into two portions. A firstarc portion extends between electrodes 5| and 62 along the axis of chamber It.

-The second portion extends between electrode 62 and elbow i9 and is displaced by the air blast to extend between elbow I9 and the lower spider 53. The first arc portion is located in a zone where the air issuing from chamber I3 at maximum velocity suddenly expands to substantially atmospheric pressure with a corresponding large drop The incandescent ionized air in the are path is therefore replaced'at a rapid rate by cold non-ionized air, thereby rendering the continuous ionization of the arc path possible only as long as the arc current remains of relatively high intensity. This portion of the arc path is shunted by resistor 64, which likewise connects electrode 6| with electrode '62.

When the flow of current through the circuit breaker decreases toward theend of the first half cycle of arcing, the'rate of ionization of the arc path by the current gradually decreases. The

so that the inductive voltage appearing across a the main. contacts upon separation thereof is negligibly small. In addition, the main contacts are then separated by a gap in air at substantially the full pressure of reservoir I lowhich has di electric properties comparable to those of high grade insulating oil. For these two reasons the transfer of the flow of current to the arcing contacts takes place without any arcing at the main contacts, which are thus protected from bummg.

are thereby separated and an arc is drawn therebetween while a blast of air is projected from the arcing chamber into the arc extinguishing chamber through orifice l1. Contacts 33, 52 finally reach the position shown in Fig. 3 of ,the drawings, the gap between contacts 5|, 52 being preferably of the order of one-half inch. As a, result of the arrangement of the arcing chamber and of the contacts forming a converging nozzle, the velocity of the air blast is maximum between the cooperating surfaces of the arcing contacts while substantially the full pressure of reservoir is maintained within the space separating the main contacts. The air blast may establish itself at maximum velocity without appreciable delayas the column of air contained within chamber 8 is already set in motion by the air previously passing through grooves 60 of contact 52. Material vaporized by thearc from'the arcing contacts is directed by the air blast away from the main contacts through orifice l1, thereby preventing injurious deposition of vaporized material on the contact surfaces of the main contacts.

When piston l fi reaches 'a predetermined posi- I tion, hollow rod 45 engages stop 51 to move conv tact 52 jointly with contact 33. Contacts 5|, 52

ionization rate of the arc path between electrodes 6| and 52 ultimately becomes lower than the rate of deionization of the arc path by the air blast. The arc between electrodes Si, 62 therefore extinguishes, the current then flowing through the circuit breaker through cylinder l2; elbow l9, the

remaining second are portion, electrode62 and bames 61, resistor 64, conductor 65, contact 21 and contact 25. This current is'limited to a relatively low value by resistor 54. The resistance of resistor N ls of relatively high value comp'ared to the inductance of circuit 3|, so that the current is substantially in phase coincidence with the voltage of the circuit. This current dissipates the magnetic energy stored in the circuit 3| by reason of the inductance thei of.

When the voltage reaches the value zero the remaining are is easily extinguished by the air blast. The voltage thereupon reverses and follows its normal wave without presenting the over-voltages that would result from a current interruption omitting the discharge of the stored energy of the circuit. The gaps between contacts 52 33 and between contacts 5|, 52 arefilled with compressed air of high insulating value and the pathof the are between electrodes GI and 52 has been fully deionized by, the air blast while the current was flowing by way of resistor 64. There is accordingly no tendency for the spaces between the contacts and between the electrodes to break downto form a new arc. The arc-path between elbow i9 and bailles 61, which. carried the low current of resistor 54, is deionized so rapidly that ignition of a new are thereat is also prevented. The air blast carrying the heat dissipated in the arc is cooled and substantially deionized by means of baflles 51.

During the above described operation, motor 2l receives air from reservoir through valve H. The cross section of the air passage between motor 24 and valve l4 and the inertia of the moving parts driven by the motor are so selected that contact 26 is separated from contact 21 when the main and arcing contacts are open and within a few cycles from the interruption of the arc. When contact 26 is fully open, solenoid 23 is preferably deenergized by any suitable known interlock (not shown) to cause reclosure of valve l4. 'Upon closureof valve 14 chamber l3 gradually returns to atmospheric pressure and wall of cylinder l2, which serves as contact. a v

The embodiment partially illustrated in Figs. 9 and 10 diifers from the embodiment illustrated .in Fig. 1 in that the-main contacts are removed from the arcing chamber, which contains only arcing contacts 5|, 52. Contact 52 is rigidly connected with piston 46 instead of being connected therewith through a spring. Cooperating movable main contacts I8, 19 are provided for bridging arcing contacts 5|, 52 as well as disconnecting contacts 26, 21. Contact I. is preferably a spring 49 returns contacts 33, 52 to the position engagement with contact 5| when contacts 32, 33 are still open a predetermined distance less than the maximum opening thereof. Contact 33 thereafter enters into resilient sliding engagement with contact 32 and finally into abutting engagement with member 34.

To reclose' the circuit breaker, solenoid 30 is momentarily energized to actuate valve 29. The valve admits air from reservoir H to motor 28 which returns contact 26 to 'the closed position.

The entire circuit breaker is then'returned to the position shown in Figs. 1 and 2.

In the embodiment partially illustrated in Fig. 6 electrode 62 is surrounded by a nested plurality of short annular conductive baflles 68, 59, Ill. Bafiies 69, 10 are separated by an insulating baffle 1| extending therefrom toward orifice I1. I

Contact 5| is provided with a plurality of ports 12 for projecting auxiliary air blasts into chamber l8 about contact 5|.

The operation of the present embodiment is generally similar to that of the embodiment illustrated in Fig. 1. An arc is drawn between contacts 5|, 52, one of its roots is transferred to arcing electrode 6| and the other root is displaced along the bore of contact 5| and of elbow IS. A number of successive approximate positions of the are during the interrupting process are shown in dotted line in Fig. 6 to clarify the explanation offth circuit breaker operation. The a ary air blasts projected through ports 12 cooperate with I the main blast projected through the bore of contact 5| to maintain the greater portion of the arc axially of chamber l8,

shown in Fig. 2. Contact 52 enters into abutting laminated contact pivotally mounted at an on a conductive extension of cylinder l2. Contact 18 is adapted to be moved to open position by means of a piston 8| movable within a cylinder 82 against the action of a spring 83. The mechanism connecting contact I8 with piston 3| is preferably of the toggle type to obtain a relatively high pressure between contacts 18 and 1!.

Cylinder 82' communicates with chamber |3 through a port-84. The walls of cylinders 82 and I2 define a passage 86 for connecting cylincausing it to come in contact with electrode".

The are is thereupon divided into a plurality of portions including a portion I3 extending between electrodes 8| and 62 and another portion ll extending from-electrode "to the wall of elbow l9. The latter portion in'turn is urged by the air blast against bafile II and is ultimately divided into a portion 16 extending between bodies 59, I! and looped over baflle "II, and a portion 11 extending between bame 68 and elbow It. The arc portions 13 and It, 11 are sequentially extinguished in the manner above set forth with respect to the embodiment illustrated in Fig. 1. .I

The embodiment illustrated in Figs. '1 and 8 differs from the embodiment illustrated in Fig. 1

mainly in that reservoir I I. has been rotated by 90 degrees to brihgarcing chamber II in vertical alinement with baflles l1 Cylinder 20 is accordingly mounted directly on cylinder l2 without 7 interposition of an elbow. As illustrated in Fig.

8 the elements contained within chambers l3 and it are generallysimilar. to those illustrated in Figs. 2

however contact 32 is rendered resilient by the saw cuts along the engages the tonic provision of a p ura ity peripherythereofp Contact and 3. In the present embodiment" ;der 1 with cylinder 82 when piston 8| is near the top of its stroke. Cylinder 41 is otherwise without connection with arcing chamber I3.

Contact 19 is integral with contact 28 but is so arranged that contact 26 engages contact 21' before contact 19 can engage contact 18.

In operation, the circuit breaker contacts being in the position shown in Fig. 5, the flow of current between. conductors 3| takes place through contacts 18,19, which oifer the path of least resistance between the conductors. Upon contacts because of .thelow inductance of the connections between the mainand arcing contacts. a

when piston 8| is near the top of its stroke it uncovers passage. .86, which connects cylinder [I with cylinder 82. Air under pressure then flows from cylinder 82 into cylinder 41 to cause actuation oi'piston 4 toward the right. Piston- 4t separates arcing contacts l|, 52 todra an..

arc therebetween. The arc is transferred to the arcing electrodes and is extinguished in the manner above set forthwith respect tov the embodiment illustrated in Pig. 1. After /a predetermined time delay depending on the dimensions of motor 24 and of contacts 20, II, the latter contacts are jointly moved-toward "open position by motor 2|. Contact ll k moved away from closed position while contact 2 still enflsagea contact l], and movement of contacts I3, 25 separates the disconnecting contacts. The diflerentcontacts of the circuit breaker then reachtheposlflqrillustrated'in Fig.:10. Uponreclos'ureotvalve ll then-reins chamberrehirns to ahnosphericpreuure and the'airpressureisalaorelelsedfromcylinders "and". Bpringfl'mchncsardngoontacts llJlandspringurehimscontactlltoclosed Torecloocthe.

andairimderpresmreisadmittedfmmrescrvoir arr-mentis ad-r mitted to-solenoid 3| which'aetuates valve 23' u to motor 2a, Contacts 19, 2c are jointly moved by-motor 28 toward closed position but the arrangement of the contacts causes reclosing of disconnecting contacts 28, before contact 19 is returned to closed position into engagement with contact 18.

Although but a few embodiments of the present invention have been illustrated and described it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

5 arcing contacts, whereby the fiuid pressure within the space between said main contacts is substantially the full pressure of saidsource during opening operation of the circuit breaker.

4. An electric circuit breaker comprising an arcing chamber having an orifice, an annular fixed contact arranged about said orifice, a movable contact arranged within said chamber cooperating with said annular contact, an arcing electrode mounted on said movablev contact coaxially with said orifice, a pair of cooperating main contacts arranged within said chamber and connected in parallel with said arcing contacts,-

sage therebetween having a cross-section area I smaller than thecross-section area of said orifice, a source of fluid under pressure, means comprising a wall. of said chamber and said con-.

tacts for'defining a gradually converging nozzle,

ending at said passage, and means defining a path for the flow oi fluid from said source to atmosphere comprising said nozzle and said passage, said path having its smallest cross section area at said passage, whereby the fluid pressure within said nozzle is substantially the full pressure of said source and the velocity of said flow of fluid is maximum between the cooperating surfaces of said contacts during opening operation of the circuit breaker.

2. An electric circuit breaker comprising an arcing chamber having an orifice, a pair of cooperating arcing contacts arranged within-said chamber and operable substantially to close said ranged within said chamber and connected in means comprising the dimensioning of said chamber and 01' said contacts and the positioning oi .said contacts within said chamber for defining 'a gradually converging nozzle ending at the cooperating surfaces of 'said arcing contacts, means for sequentially separating ,said main contacts and separating said arcing contacts to draw an arc therebetwen, and means for transferring said are from said movable'arcing contact to said electrode comprising means defining a path for thefiow of fluid from said source through said nozzle and through said orifice to atmosphere. 1 5. An electric circuit-breakercomprising an arcing chamber having an orifice, a fixed annular arcing contact arranged about said orifice,

a movable arcing contact arranged within said chamber and operable substantially to close said orifice, a fixed annular main contact arranged coaxially with said annular arcing contact and connected therewith, a movable annular main contact arranged about said movable arcing contact coaxiallytherewith and connected therewith, means for separating said main contacts and for thereaiter'separating said arcing contacts to transfer the flow of current from said main contacts to said arcing contacts and to v orifice, a pair of cooperating main contacts ardraw an are between said arcing contacts, a

source of fluid under pressure, means comprising the dimensioning of said chamber and of separating said main contacts and for thereafter separating said arcing contacts, a source of fluid under pressure, means comprising the dimensioning of said chamber and of said contacts and" the positioning of said contacts within said chamber for defining a gradually converging nozzle ending at the cooperating surfaces of said arcing contacts, and means for directing material vaporized from said arcing contacts during opening operation of the circuit breaker away from said inain contacts through said orifice compris ing means defining a path for the flow of fluid from said source through said nozzle and said orifice to atmosphere.

3. An electric circuit breaker comprising an arcing chamber having an orifice, a pair of cooperating arcing contacts arranged within said chamber and operable substantially to close said orifice, a pair of cooperating main contacts arranged within said chamber and connected in parallel with said arcing contactsfmeans for separating said main contacts and for thereafter separating said arcing contacts, a source of fiuid under pressure, means defining a path for the fiow oi fluid from said source through "said contacts and the positioning of said contacts'within said chamber for defining a gradual- 1y converging annular nozzle ending at the" cooperating surfaces of said arcing contacts, and

means for preventing burning of said main contacts during opening operation of the circuit breaker comprising the relative positioning of said main and arcing contacts to limit the inductance of the connections between said contacts to a relatively low value and means defining a path for the flow of fiuid from said source through said nozzle and through said orifice to atmosphere;

- 6. An electric circuit breaker comprising a pair of'relatively movable conductive members,

a flexible conductor for interconnecting said jinembers. a resilient member acting on the first said members through difierent portions of said 4 conductor to clamp said conductor against the said circuit breaker to atmosphere, and means ior preventing arcing between said main contacts upon separation thereof comprising a gradually converging nozzle defined within said path ending at the cooperating. surfaces of said 75 first said members in conductive relation therewith, and stop means on the first said members for limiting the relative movement of the first said members under the-action of said resilient member. Y

"I. An electric circuit breaker comprising an annular conductive member bounded by intersecting plane and cylindrical surfaces, a plurality .of contact segments arranged about said cylindrical surface to define a concave contact suriace ot revolution, means for pivotally mounting said segments on said member and for resiliently urging said segments against said cylindrical surface, a cylindrical contact coaxial with said 6 member bounded by intersecting plane and cylindrical surfaces, and means for'moving said cylindrical contact toward said member to. causesequential sliding engagement of the cylindrical surface of said cylindrical contact with the concave surface of, said segmentsand abutting engagement of the plane surface of said cylindrical contact with the plane surface of said member.

8. An electric circuit breaker comprising a pair of cooperating arcing contacts, a pair of cooperating disconnecting contacts serially connected with said arcing contacts, cooperating main contacts for bridging said arcing and disconnecting contacts, one of said main contacts being integral with oneof said disconnecting contacts, and means for sequentially opening saidmain, arcing, and disconnecting contacts.

9. An electric circuit breaker comprising a pair of cooperating arcing contacts, a pair of cooperating disconnecting contacts serially connected with said arcing contacts, cooperating movable main contacts for bridging said arcing and disconnecting contacts, and means for sequentially moving one of said main contacts to open position, separating said arcing contacts, moving the other one of said main contacts toward open position and separating said disconnecting contacts. 110. An electric circuit pair of cooperating arcing contacts, a pair of cooperating"disconnecting contacts serially connected with said arcing contacts, cooperating first and second movable main contacts for bridging said arcing and disconnecting contacts, means for causing-opening of the circuit breaker comprising means for sequentially moving said first main contact to open position, separating said arcing contacts, moving said second main contact toward open position, separating said disconnecting contacts, reclosing said arcing contacts and returning said first main contact to closed position, and means for causing closing of the circuit breaker comprising means for sequentially'reclosing said disconnecting contacts and returning said second main contact to closed position.

11. An electric circuit breaker comprising a resistor, means comprising an electrode in the path of said are at a predetermined distance from said hollow contact for connecting said resistor between said contacts, said electrode being arranged axially in the discharge path of said blast, and a plurality of conductive partitions at a common potential arranged about said electrode at a distance from said hollow contact greater'than said predetermined distance dividing the discharge path of said blast carrying the arc drawn between said electrode and said hollow contact.

13. An electric circuit breaker comprising an arcing chamber having an orifice, an are extinguishing chamber communicating with said arcing chamber through said orifice, an annular fixed contact arranged about said orifice, a movable contact arranged within said arcing chamber, an electrode arranged within said arc extinguishing chamber at a predetermined distance from said orifice, a resistor connecting said electrode with said movable contact, means for separating said contacts to draw an are therebetween, a plurality of coaxial conductive batiles at a common potential arranged about said electrode in said are extinguishing chamber at a distance from said orifice greater than said prebreaker comprising a determined distance, and means comprising a source of fluid under pressure for projecting a blast of fluid from said arcing chamber through said orifice into said are extinguishing chamber, said blast intersecting the path' of said arc between said contacts to cause transfer of a por- -tion of said are to another path between said ct, said blast also re path to drive electrode and said fixed con intersecting the second said said arc toward said bailies.

14.. An electric circuit breaker comprising an arcing chamber having an orifice, an are extinguishing chamber communicating with said,

arcing chamber through said orifice, an annular fixed contact arranged about said orifice, a movable contact arranged within said arcing chamarcing chamber having .an orifice, an are extinguishing'chamber communicating with said ing said electrode within said are extin'gushing chamber in insulated relation with the other one of said contacts, meansior separating said contacts to draw an arc therebetween, means ber, an electrode arranged within said arc extinguishing chamber, a resistor connecting said electrode with said movable contact, "means for separating said contacts'to draw an are therebetween, baflle means arranged adjacent said electrode comprising a pair of conductive bailles separated by an insulating baflie extending therefrom toward said orifice, and means comprising a source of fluid underpressure for projecting a blast of fluid from said arcing chamber through said orifice into said-arc extinguishing chamber,-

said blast causing said am to be displaced and divided into a plurality of serially connected por-' tions includinga portion extending between said movable contact and said electrode and another portion extending between said conductive'bames for projecting a blast of fluid under pressure from said arcing through said orifice to cause transfer of said are to said electrode and to cause extinction of said arc, whereby material I vaporized from said contacts is deposited on' said.

insulating means-and shield means adjacent a portion of the-surface or said insulating means to prevent deposition of said material on said portion of the surface 0! said insulating means,

thereby preventing formation of a conductive path between said electrode and said other one of said contacts by way of said material.

12. A circuit breaker comprising cooperating arcing contacts. one of said contacts being a hollow, contact, means for projecting ablast of fluid under pressure through said hollow contact to blasts of fluid into said extinguishing chamber and looped over said insulating baflle.

15. An electric circuit breaker comprising an arcing chamber having an orifice, an are extlnguishing chamber communicating with said arcing chamber through said .orifice, an annular fixed contact arranged about said orifice, a movahiecontact arranged withinsaid-arcing chamto cooperate with said fixed -contact,vmeans f separating said-contacts to draw an are therebetween, means tor projecting a blast'ot fluid pressure said arcing chamber through said orifice to -drive said are. into said extinguishlng chamber, and means for ,guiding said are toward the axis or said extinguishing chamber comprising means for projecting auxiliary extinguish an are drawn between said contacts. about said annular contact.

' 16. A circuit breaker comprising a fixed main contact, a movable main contact, means for urging said movable main contact into engagement with said fixed main contact, means for separating said main contacts, a fixed arcing contact, a movable arcing contact resiliently mounted on said movable main contact to engage and disengage said fixed arcing contact when said movable main contacts are open at a distance less than the maximum opening thereof, means comprising a source of fluid under pressure for directing a blast of are extinguishing fluid on said arcing contacts, and means for preventing opening of said arcing contacts before opening of said main contacts comprising means for guiding said blast to cause said blast to urge said movable arcing contact toward engagement with said fixed arcing contact.

GUSTAV E. JANSSON.

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