US2645695A - Electric circuit breaker with arcing contacts in skew blast - Google Patents

Description

July 14, 1953 P. L. TAYLOR 2,645,695

ELECTRIC CIRCUIT BREAKER WITH ARCING CONTACTS IN SKEW BLAST Filed Feb. 23, 1949 2 Sheets-Sheet l July 14; 1953 P. L. TAYLOR ELECTRIC CIRCUIT BREAKER WITH ARCING CONTACTS IN SKEW BLAST 2 Sheets-Sheet 2 Filed Feb. 25, 1949 AW W a Patented July I 4, 1953 I ELECTRIC CIRCUIT BREAKERWITH ARCING CONTACTS IN SKEW BLAST Philip L. Taylor, AbingtonfMass assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application February 23, 1949, Serial No. 77,824

, 8 Claims. 1

This invention relates to switching devices such as electric circuit breakers of the fluid blast type and more particularly to means for improving the interrupting capacity thereof. In the operation of circuit breakers of the fluid blast type, the current interruption takes place under the most advantageous conditions when the arcing contacts are rapidly separated to permit the fiow-therebetween of a blast of fluid of maximum velocity obtainable from the available source. In order to be sure that restriking of the arc'does not occur, isolating or disconnect contacts are frequently provided in addition to the arcing contacts and are opened after the arc has been extinguished but while the fiuid blast is still being maintained.

Heretofore, axial type air blast circuit breakers employing a nozzle type fixed contact having an annular or circular contact surface and a cooperating movable plug contact have been used. At the time of separation of this type of contacts, a small annular or circular gap is formed therebetween and the arc formed upon separation thereof, during its state of inception, extends transversely across the gap. The blast of air under pressure for extinguishing the arc escapes along all of the 350 degrees of gap circumference, yet only a few degrees of that circular blast is utilized and effective in deionizing the arc path. Thus, the ratio of that portion of the blast which is utilized and efiective in deionizing the arc path and extinguishing the arc, to the total volume of gas escaping through the circular gap, is relatively low. Obviously, this is conducive to low 'interruptingefficiency of the axial air blast circuit breaker using cooperating nozzle and plug type arcing contacts.

The above described limitations of the axial type circuit breaker employing cooperating nozzle and plug type arcing contacts led to the development of axial type circuit breakers having different type of arcing contact arrangements. One of the contact arrangements de veloped for interruption of high currents comprised an insulating gas blast nozzle and a pair of butt contacts arranged therein and separable in a direction longitudinally thereof. This type of arrangement proved to be capable of interrupting currents of higher magnitude than was possible with arrangements having nozzle and plug contacts, yet it had a definite drawback consisting in the fact that the upstream contact was an impediment limiting the effectiveness of the arc blast-along the zone of the common geometrical axis of both contacts.

It is therefore one object of the present invention to provide a new and improved circuit breaker of the fluid blast type in which an are formed upon separation of a pair of cooperating arcing contacts is biased in substantially a single direction transversely of the direction of separation of the arcing contacts.

A further object of the present invention is to provide anew and improved circuit breaker of the fluid blast type in which substantially all of the fluid blast is utilized in extinguishing the are formed upon separation of arcing contacts embodied therein.

A still further object of the present invention is to provide a new and improved circuit breaker of the fluid blast type in which a blast of fluid under pressure established past a pair of cooperating arcing contacts and through the gap formed upon separation thereof is controlled and directed by the contacts.

Objects and advantages other than those set forth will be apparent from the following description when read in connection with the accompanying drawing in which:

Fig. 1 is a diagrammatic view, partly in elevation and partly in section, of a circuit breaker embodying the present invention;

Fig. 2 is an enlarged View in an axial cross section through the interrupting head of the circuit breaker illustrated in Fig. l; and

Fig. 3 is a view in axial cross section through a portion of a modified embodiment of the interrupting head illustrated in Figs. 1 and 2.

Referring more particularly to the drawings by characters of reference, Fig. 1 illustrates a circuit breaker including as a constructive element thereof a reservoir 2 constituting a source of supply of fluid under pressure, which will be assumed herein to be compressed air, supplied from a suitable compressor (not shown). Although in general, circuit breakers of the type herein considered are provided with a plurality of similar switch elements or pole units to be inserted in the several conductors of a polyphase electric circuit, only one such pole element is shown in Fig. 1 and the circuit breaker will be described in detail as if it were of the single pole type.

The circuit breaker, for example, may 'comprise a fixed arcing contact 3 and a cooperating movable arcing contact 4' connected in series with a disconnecting switch comprising a fixed disconnect contact 5 and a cooperating movable disconnect contact 6 in an electric circuit through stud terminals 1 and 8. The arcing contacts 3 and 4 are housed in a tubular arcing chamber 9, having a metallic sleeve shaped wall axially aligned with and supporting an insulating sleeve II and an insulating sleeve l2. The metallic sleeve 16 of chamber 9 constitutes a conductive connection between the fixed arcing contact 3 and an extension of terminal 8. Sleeve ll constitutes a discharge passage for chamber 9.

Sleeve [6, as more clearly illustrated in Fig. 2, is provided with an inwarly extending bracket l3 upon which is arranged a contact constituting the fixed arcing contact 3 of the circuit breaker. The cooperating movable arcing contact 4, which may be in the form of a streamlined solid of revolution, is actuated by a piston ll slidable in a cylinder I9 and secured by pins I8 to a stud I 8. Arcing contact 4 is suitably secured to a stud 20 which is slidably mounted in an insulating bushing 2! and biased to closed position by a spring 22 acting between a bushing 23 secured to stud 20 and an extension 24 of piston H. The stud 20 is conductively connected to the stud It by means of flexible conductors 25.

A pair of main or current carrying contacts 26 and 2'! are in parallel with the arcing contacts 3 and 4. Contact is preferably made in a series of segments resiliently mounted, as shown, to form an annular stationary contact. The movable current carrying contact 2'! is a metallic sleeve member 28 which is secured to insulating sleeve 2! and piston ll so as to move with piston ll upon actuation thereof. Thus, current entering from terminal 8, flows through metallic sleeve l0, main or current carrying contacts 26 and 21, sliding contacts [4 and disconnect contacts 5 and 6 to the terminal 1. Although the arcing contacts when closed are in parallel with the main or current carrying contacts, the flow of current will generally pass almost entirely through the main contacts because of the relatively small area of the cooperating surfaces of the arcing contacts and because of the higher resistance thereof.

The movable current carrying contact 2'! is urged into engagement with the fixed current carrying contact 26 by resilient means such as a spring 29 acting between piston H and a metallic Washer which is resiliently supported in a metallic sleeve portion 3|. The metallic sleeve portion 3| is supported by insulating sleeve l2 at the free end thereof. axially aligned with sleeves l0, H and 12. In addition sleeve portion 31 is provided with an extension arm 32 which supports the fixed disconnect contact 5.

The movable disconnect contact 6 may be pivotally mounted on a bracket 35 which is secured to an extension of terminal 1. One end of a connecting rod 36 may be connected at a point 3! intermediate the ends of movable disconnect contact 6, and the other end of rod 36 may be connected to an arm 38 of a bell crank 39. A second arm 40 of bell crank 39 may be connected to the piston rod 41 of a fluid motor 42. The rod 41 protrudes through and beyond the ends of a cylinder 43 of motor 42. Motor 42 actuates the bell crank 39 which, in turn, actuates the connecting rod 35. A predetermined movement of connecting rod 36 actuates the movable disconnect contact 6 and moves it to its open and closed positions. A pair of regulating valves 44 and 45 may be utilized for regulating the supply of fluid from reservoir 2 to motor 42.

A mechanical interlocking device for precluding improper sequence of operation of the disconnect contacts 5 and 6 with reference to the Sleeve portion 3| is v arcing contacts 3 and 4 is provided for proper circuit breaker operation. The mechanical interlocking device comprises a bent lever 48 which is pivotally mounted on a bracket 49 and arranged to lie within the path of relative movement of the arcing contacts, which, in the embodiment shown, is the path of movement of contact 4 or of the stud [6 which is actuated with contact 4. Lever 48 also lies in the path of relative movement of the disconnect contacts which, in the embodiment shown, is the path of movement of contact 6, for preventing separation of the disconnect contacts 5 and 6 prior to the opening of arcing contacts 3 and 4. A biasing means, such as a spring 50, pivots the lever 48 into the path of movement of the movable disconnect contact 6 and prevents separation thereof from the stationary or fixed disconnect contact 5 in case of maladjustment of the means which controls the sequence of the fluid motor for operating arcing contact 3.

The compressed air for operating the circuit breaker control system and the arcing contacts is derived from the reservoir 2. The air under pressure in reservoir 2 also produces the are extinguishing blast across the gap formed between the pair of cooperating arcing contacts 3 and 4 upon separation thereof. The are extinguishing blast from reservoir 2 to the arcing contacts 3 and 4 is controlled by a blast valve 5| which provides a connection between the reservoir 2 and a conduit 52 which is connected to the metallic sleeve portion I0 of chamber 9.

In accordance with the present invention arcing contacts 3 and 4 may be arranged to engage within a nozzle 53, which is arranged within the passage formed by chamber 9. At least the portion of nozzle 53 extending downstream from the point of engagement of contacts 3 and 4 is made of refractory insulating material. Nozzle 53 establishes a zone of high velocity for the blast of fluid under pressure supplied to chamber 9 from reservoir 2 through conduit 52. In order to utilize substantially all of the arc extinguishing blast of fluid under pressure a means, such as guiding surface 54 of nozzle 53, is provided for producing a skew blast of fluid under pressure for biasing the are formed upon initial separation of the arcing contacts 3 and 4 in a direction transverse to the direction of separation of the arcing contacts. Guiding means 54 provide a substantially rectilinear path through the gap formed upon separation of the arcing contacts 3 and 4 for the blast of gas under pressure. The guiding means are so arranged that the blast of gas sweeps in substantially a single direction substantially the full area of the arcing contacts as well as the total engaging areas of the contacts. The blast is designated as a skew blast for the reason that its direction of flow is oblique with respect to the engaging surface of the arcing conacts.

The oblique or skew blast of fluid under pressure passing through the gap formed uponseparation of the arcing contacts 3 and 4, effectively sweeps a larger portion of the arc and are path or zone than would a cross or axial blast of fluid of the same cross section. By sweeping a greater portion of the arc with a given blast of fluid, deionization of the arc occurs more rapidly due to the fact that the skew blast removes a greater portion of the ionized gas and simultaneously replaces it with un-ionized gas.

In order to rapidly and effectively extinguish an are, it is desirable to also sweep the arcing contact surfaces, thus sweeping and in turn'reducing the concentration of electrons and positive ions in the regions of high ion concentration. By the removal of ions concentrated around the arcing contact surfaces as well as.

along the arc path, rapid deionization of the arc zone occurs when the gas throughout that zone is in a state of agitation. lhe rate at which the arc path is deionized is an important factor, and it is a general aim in the design of circuit breakers to increase that rate as much as possible in order to accomplish rapid and efiicient circuit interruption.

The path of current flowing through arcing contacts 3 and 4 bends sharply at the contact engaging surfaces thereof, thus, forming a loop shaped current path which produces a magnetic means for aiding in biasing the are formed upon initial separation of the arcing contacts into guiding means 54.

Nozzle 53 communicates with the insulating sleeve I l which in turn communicates with a deionizing chamber 55. The sleeve I i may contain an auxiliary arcing electrode 55 which is usually affixed thereto. lhe auxiliary arcing or probe electrode 56 may be connected with the movable contact 21 through a current limiting resistor 51', a conductor 53, and contacts [4.

When current is to be interrupted, contact 4 is moved out of engagement with contact 3. An arc is drawn between the cooperating surfaces of the contacts. The are causes material of the contacts to be vaporized or otherwise removed with explosive force between the contacts. A large portion of the removed contact material, in the form of incandescent particles, metallic vapors, and clouds of metallic oxides, is directed by the guiding means 54 and is sprayed toward deionizing chamber 55.

The contact material reaching chamber 55 is partly deposited on the walls thereof and some of the contact material remains in suspension in the gas contained therein. Nozzle 53 and a tube 46 jointly constitute pocket defining means which establish an annular zone 41 to trap part of the contact material remaining in suspension by forming an eddy in such zone. Structures defining zones such as zone d1 are more fully described and claimed in U. S. Patent 2,426,250 dated August 26, 19 :7, Philip L. Taylor, and U. S. Patent 2,570,610 dated October 9, 1951, Philip L.

' Taylor.

A slide valve 6| controls blast valve 55 by opening and closing an inlet port (not shown) of blast valve 5| upon a predetermined movement of rod 4! of motor 42. Connecting rods 52 and 63 interconnected by link 54, and connected to slide valve 61 by means of link 65, form the mechanical connection for connecting rod 41 of motor 42 to slide valve 6!. I

A pair of opening and closing means such as solenoid type control valves 68 and 69, respectively, control the actuating means for the circuit breaker. Both control valves 68 and 59 are connected to reservoir 2 by a common conduit '55.

A slide or piston type interlocking valve 7! is provided and arranged in a conduit l2, 72 for connecting the closing valve 55 and the fluid operated motor 42. This type of valve is more fully system in the corresponding position. A closing I6 operation is initiated by energization of the closing solenoid valve 69, thereby causing air under pressure from reservoir 2 to pass through conduit 19, valve 69, conduit 12, valve ll, conduit 72 to fluid motor 42. Operation of solenoid valve .69 results in the piston (not shown) of motor 42 moving from right to left to actuate rod 4!, bell crank 39, and connecting rod 35, thus closing the disconnect contacts 5 and 5. The'movement of the piston of fluid motor 42 from right to left rotates link 54 clockwise, and this results in an upward movement of connecting rod 53 which in turn rotates link 55 in a clockwise direction. The clockwise rotation of link 65 actuates slide valve 6| in an upward direction, thus opening a port from trip valve 58 to blast valve When the solenoid trip valve 68 is energized, compressed air flows from reservoir 2, through conduit 19, tripvalve 58, and a conduit 8!, through slide valve 6% and into blast valve 5!. This initiates the operation of blast valve 5!. Upon being openedblast valve 5i permits a blast of air under pressure to flow through conduit 52, an inlet port 82 of sleeve portion 15, and into chamber 9. Air under pressure in chamber, 9 actuates piston H, and piston ll separates current carrying contact 2'! from current carrying contact '25. Contact 21 moves bushing 2! down- Ward, and upon impact of bushing ii on bushing 23 stud 2c is also actuated downward to separate arcing contact 4 from arcingcontact Upon the separation of arcing contacts 3 and 4 a skew blast is provided which sweeps the arcing contacts 3 and 4 and their engaging surfaces in a single direction transverse to the movement of the movable arcing contact 4 and extinguishes the are occurring upon separation of arcing contacts 3 and 4.

Movement of stud 16, which is actuated by piston ll, actuates lever The movement of lever 48 moves one arm thereof out of the path of movement of the movable disconnect contact 6. 7

Upon the flow of the air blast through conduit 52, air under pressure therefrom is transmitted with a slight delay through a conduit d3. connected thereto and to the left hand side of motor 42. This pressure impulse moves the piston of motor 42 from left to right, thus resulting in the separation of the disconnect contacts 5 and 6. If the desired predetermined sequence of the actuating means for operation of the arcing contacts 3 and 4 and the disconnect contacts 5 and 5 does not occur, the lever 48 will prevent disconnect contacts 5 and 5 from separating. However, upon the proper sequence of operation lever 48 will be moved out ofthe path of movement of disconnect contacts 5 and 5 without physical contact therewith before fluid motor 42 actuates disconnect contacts 5 and'6.

Upon the flow of an air blast through conduit 52, air under pressure therefrom is transmitt d through a conduit 84 to valve ll. This pressure impulse closes valve .ll and precludes the possibility of air under pressure being supplied to motor 42 through conduit l2, Which might result in improper closing the disconnect contacts 5, 6 prematurely.

Fig. 3 shows a modification of the contact structure shown in Figs. 1 and 2. In this embodiment of the present invention the plug shaped movable arcing contact 85 is formed to provide a surface 86, other than the contact engaging surface 8'! thereof, which controls the blast in guiding nozzle 88 upstream of the contact engaging surfaces 81 of movable contact 85 and 89 of the fixed arcing contact 90. Surface 86 may be defined by metal of contact 85 itself or by insulating material attached to the contact. Control of the blast through nozzle 88 by surface 86 may be achieved without actual engagement between nozzle 88 and surface 86 by varying the width of th gap between these two parts without ever reducing it to zero. Guiding surface 9| of the nozzle provides a skew blast in a single direction transverse to the direction of movement of the movable arcing contact 85.

The movable arcing contact 85 is so arranged as to control the amount of gas under pressure passing through nozzle 88 prior to as well as during the time of contact separation. Hence there is but a small drop of pressure at the point of contact separation prior to the time of contact separation. The fluid under pressure stored up to the point of contact separation and at that time released is in the form of a blast of maximum kinetic energy and is entirely available for are extinction.

Although but two 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 th scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In an electric switching device the combination of an arcing chamber defining a passage, means for establishing a blast of gas through said passage, nozzle means arranged within said passage for establishing a zone of high velocity of said blast of gas, a pair of cooperating butt contacts arranged within said nozzle means and engaging within said zone of high velocity, means for separating said contacts, pocket defining means arranged within said passage and situated downstream of said nozzle means for receiving products of arcing, and means for biasing the are formed upon initial separation of said contacts in substantiall a single direction oblique to the direction of separation of said contacts.

2. In a fluid blast circuit breaker a member at least in part of insulating material forming a nozzle having a zone of restricted cross section between the openings thereof, means for producing a blast of fluid through said nozzle, a metallic plug element cooperating with said nozzle forming member for controlling said blast, a pair of separable contacts engaging within said zon of restricted cross section of said nozzle at a point spaced from the lateral wall thereof, one of said contacts being constituted by an arcing tip on the down stream end of said plug element, said plug element and said arcing tip being in the form of a solid of revolution, means for operating said plug element to open said nozzle and separate said contacts, and means for biasing a preponderant portion of the blast enveloping said plug element upon operation thereof in a direction oblique to the axis of said plug element, said biasing means including portions of the lateral wall of said nozzle inclined relative to said axis of said solid of revolution.

3. In a gas blast circuit breaker a nozzle defining member of insulating material providing an orifice having a lateral slot, means for establishing a blast of gas through the nozzle defined by said member, a plug element cooperating with said nozzle defined by said member for controlling said blast, a pair of separable butt contacts engaging 'within said orifice defined by said member, one of said contacts projecting through said lateral slot into said orifice, and the other of said contacts forming an integral part of said plu element.

4. In a gas blast circuit breaker a member of insulating material forming a nozzle and means for establishing a blast of gas through said nozzle, at least the exhaust end of said nozzle forming member being of heat shock resistant insulating material, a plug element cooperating with said nozzle forming member for controlling said blast, a pair of separable contacts engaging within said nozzle at a point spaced from the lateral wall thereof, one of said contacts forming an apex portion on said plug element, and a plurality of means for biasing the are initiated upon separation of said contacts in the same general direction, said plurality of means including magnetic arc biasing means and wall means for guiding a preponderant portion of the blast enterin said nozzl obliquely across the gap formed between said contacts upon separation thereof.

5. In a fluid blast circuit breaker a substantially cylindrical member at least in part of insulating material defining a nozzle of circular cross section having a zone of restricted cross section between the openings thereof, said openings being arranged in eccentric relation at opposite sides of the longitudinal axis of said nozzle defining member, means for establishing a blast of fluid through said nozzle, a plug element within said nozzle for controlling said blast, a pair of contacts engaging within said zone of restricted cross section of said nozzle at a point spaced from the lateral wall thereof, one of said contacts forming an integral part of said plug element, and a fluid motor comprising a cooperating piston and cylinder arranged coaxially with respect to said nozzle defining member for opening said nozzle and separating said contacts.

6. In a fluid blast circuit breaker a member at least in part of insulating material forming a nozzle having a zone of restricted cross section between the openings thereof, means for establishing a blast of fluid through said nozzle, a plug element cooperating with said nozzle forming member for controlling said blast, a pair of contacts at least one of which is retractable engaging within said zone of restricted cross section of said nozzle at a point spaced from the lateral wall thereof, one of said contacts forming an integral part of said plug element and being arranged at the downstream end thereof, common means for retracting said plug element and said one of said contacts to nozzle and contact open position, said nozzle, said plug element and said one of said contacts defining in nozzle and contact open position an annular asymmetrical passage causing the preponderance of said blast to flow across the gap formed between said contacts upon operation of said retracting means in a direction angularly related to the direction of movement of said retracting means.

'7. In a fluid blast circuit breaker, a member of insulating material forming a nozzle having a substantially conical entrance portion, means for producing a blast of fluid through said nozzle, a substantially conical plug element of metal coopcrating with said substantially conical entrance portion of said nozzle for controlling said blast, a pair of separable butt contacts engaging within said nozzle at a point spaced from the lateral wall thereof, one of said contacts forming an apex portion on said plug element, and the other of said contacts being constituted by an angle member, one arm of said angle member forming an arc runner extending in downstream direction for transferring one terminal of the are formed upon separation of said contacts adjacent the exhaust end of said nozzle.

8. In a fluid blast circuit breaker, a member of insulating material substantially in the shape of two coaxial superimposed cylinders having different diameters, said insulating member defining a nozzle having a zone of restricted cross section between the openings thereof, a tubular passage defining means arranged coaxially with respect to and surrounding the small diameter portion of said insulating member, are restraining structure within said passage defining means, means for establishing a blast of fluid through said insulating member and said passage defining means, a plug element arranged within said insulating member for controlling said blast, a pair of contacts engaging within said zone of restricted cross section of said nozzle at a point spaced from the lateral wall thereof, one of said contacts forming, an integral part of said plug element, and common operating means for moving said plug element and said one of said contacts in the direction of the common axis of said insulating member and said passage defining means.

PHILIP L. TAYLOR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,967,989 Clerc July 24, 1934 2,049,328 Skeats July 28, 1936 2,049,996 Clerc Aug. 4, 1936 2,370,340 Wood Feb. 27, 1945 2,392,647 Cox Jan. 8, 1946 2,426,250 Taylor Aug. 26, 1947 2,439,264 Paul Apr. 6, 1948. 2,451,669 Eichenberger Oct. 19, 1948 FOREIGN PATENTS Number Country Date 85,565 Sweden Feb. 18, 1936. 451,434 Great Britain Aug. 6, 1936 610,058 Germany Mar. 1, 1935 660,394 Germany May 21, 1938 708,318 Germany July 1'7, 1941

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