US3621169A

US3621169A - Electric circuit interrupter with novel arc gas discharge muffle assembly

Info

Publication number: US3621169A
Application number: US28259A
Authority: US
Inventors: Eldon B Heft; Harold A Humpage
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1970-04-20
Filing date: 1970-04-20
Publication date: 1971-11-16
Anticipated expiration: 1988-11-16

Abstract

An electric circuit interrupter including arc establishing and interrupting means having an arc-gas venting portion and an arcgas filter and muffle portion in juxtaposed relation to the arcgas venting portion, combined with a sleeve of elastomeric material surrounding the muffle portion and at least a portion of the arc establishing and interrupting means, the sleeve including a circumferentially extending inwardly directed rib positioned between the muffle portion and the arc establishing and interrupting means, the sleeve serving to prevent the flow of gases other than in the intended path of flow through the assembly. In accordance with another aspect, a plurality of arc generating and interrupting assemblies are positioned side by side to provide a multipole device, and an integral metallic, generally boxlike, enclosure is provided surrounding all of the interrupting assemblies and having an end wall with openings therein permitting the flow of arc gases therethrough, the metallic enclosure permitting the device to withstand extremely high pressures during interruption.

Description

United States Patent 2,133,158 11/1938 Ver Planck etal.

Inventors Eldon B. Heft W. Hartford; Harold A. Humpage, Forestviiie, both of Conn.

Appl. No. 28,259

Filed Apr. 20, 1970 Patented Nov. 16, 197i Assignee General Electric Company Continuation of application Ser. No. 593,945, Nov. 14, 1966, now abandoned.

ELECTRIC CIRCUIT INTERRUPTER WITH NOVEL ARC GAS DISCHARGE MUFFLE ASSEMBLY ZOO/149.2 X

2,272,214 2/1942 Linde .i

ZOO/148.3

ABSTRACT: An electric circuit interrupter including arc establishing and interrupting means having an arc-gas venting portion and an arc-gas filter and muffle portion in juxtaposed relation to the arc-gas venting portion, combined with a sleeve of elastomeric material surrounding the muffle portion and at least a portion of the arc establishing and interrupting means, the sleeve including a circumferentially extending inwardly directed rib positioned between the muffle portion and the arc establishing and interrupting means, the sleeve serving to prevent the flow of gases other than in the intended path of flow through the assembly.

in accordance with another aspect, a plurality of are generating and interrupting assemblies are positioned side by side to provide a multipole device, and an integral metallic, generally boxlike, enclosure is provided surrounding all of the interrupting assemblies and having an end wall with openings therein permitting the flow of arc gases therethrough, the metallic enclosure permitting the device to withstand extremely high pressures during interruption.

49A 498 49c 29 7 24 20 i f,

29a Q l ii i 0 L L J 7/8 I 69 ELECTRIC CIRCUIT INTERRUPTER WITH NOVEL ARC GAS DISCHARGE MUFFLE ASSEMBLY This application is a continuation of application Ser. No. 593,945, filed Nov. 14, 1966, now abandoned.

Our invention relates to electric circuit interrupters, and more particularly to electric circuit interrupters of the current-limiting type, including means for minimizing the discharge of hot arc gases and the magnitude of noise and shock wave emerging therefrom.

Copending application Ser. No. 594,048 filed Nov. 1966 by E. B. Heft now US. Pat. 1969 and assigned to the same assignee as the present invention discloses the construction and functioning of an electric circuit breaker of the type described including novel and highly effective means for clearing the arc discharge gases and for muffling the noise and shock wave otherwise emitted therefrom in the course of interruption of an extremely high short circuit current such, for example, as 100,000 amperes at 600 volts. As disclosed in the aforesaid application, one of the desirable novel aspects of the construction disclosed is its relatively small and compact physical size despite the high pressures of gas developed therein during interruption of high short circuit currents. As one means of achieving this relatively small size, in accordance with the aforesaid application, there is disclosed a housing or enclosure for the arc discharge filter apparatus comprising a generally boxlike sheetmetal en closure closely fitting around the arc discharge filter and muffle assembly. Moreover, in the three-pole form disclosed, the arc muffle and filter enclosure comprises a metallic box having an end wall with apertures therein for the passage of the arc gases, and a pair of sidewalls for attachment to the basic arc-establishing apparatus, and also a pair of intermediate sheet metal walls dividing the total enclosure into three separate compartments each substantially totally enclosed on all three sides by metal. This metallic enclosure or jacket lends high strength to the arc muffle assembly against the compressive forces of gas generated therein, without occupying a great amount of space.

Because of the presence of the metal on three sides of each of the arc muffle assemblies, great care is required to prevent striking over from one or more of the pole assemblies to the metal enclosure which might thereby initiate a phase-toground or phase-to-phase fault causing possible destruction of the device.

In accordance with the aforesaid application, insulating liner means is provided for each of the arc muffle assemblies comprising a pair of generally rectangular tubular wrappings of cellulosic fiber insulating material having their seams staggered, or on opposite sides of the assembly so that no crack is provided affording access directly to the metal. The aforesaid insulating tube assembly surrounds each of the arc muffle assemblies and insulates it from the outer metallic jacket. While this construction has been found generally satisfactory in operation, occasional unusual situations were encountered during tests in which restriking or retrogressions of the arc were found to occur which, although not preventing successful operation, are generally undesirable as tending to shorten the life of the device. Although a definitive analysis of what is taking place is virtually impossible because of the extremely high-speed explosive character of the phenomenon involved, and because of limitations upon present knowledge of arc and gas behavior at explosive speeds, our analysis of the source of difficulty was as follows.

As disclosed in the aforesaid application, circuit interrupters of the type involved comprise an arc-establishing portion involving movable contacts which are moved to create and elongate an electric arc, the arc products of which are then to be vented to the outer air. The function of a filter or muffle in this connection is to be distinguished from the primarily electrical function of an arc extinguishing assembly whose primary function is either to (I) deionize and therefore assist in interruption of the are or (2) cool and control the arc gases as they emerge from the circuit interrupter for the purpose of preventing flashover external of the circuit breaker. The func- 14, No. 3,448,231 issued June 3,

tion of the mufile in the case of the present invention and that described in the aforesaid application is, on the other hand, to (1) reduce the danger to adjacent apparatus and personnel from the jet of flame and hot gas which otherwise would issue from the current-limiting circuit breaker and 2) to reduce the magnitude of the noise generated by the interruption so as to avoid discomfort and possible injury to the ears of personnel in the vicinity, and (3) to reduce the force of any compressive shock wave generated and emitted by the device.

It is speculated that in cases where restriking or retrogressions occurred with the prior structure, that some of the gases emerging from the arc establishing device at extremely high pressure were being blown into the cracks between the arc muffle assembly and the means used to establish the arc, such gases in effect getting on the wrong side of the insulating structure and getting to the outside of the assembly where they could strike a grounded metal portion such as metallic casing 40 and cause a failure. Also, such gases were blown into cracks between the insulating structure and bolts used to hold the assembly together, also causing grounding.

It is an object of the present invention to provide an arc chute filter and muffle assembly of the type described in the aforesaid patent application which includes means for providing a more effective gas seal between the chamber through which the arc gases must pass and the surrounding case.

It is a more particular object of the invention to provide a seal means of the type described which shall provide a valve" action so that the effectiveness of the seal will increase in proportion to the pressure exerted thereupon.

It is a further object of the invention to provide sealing means of the type described which is relatively simple to manufacture and assemble, and also which does not generate any gases which will adversely affect operation of the currentlimiting circuit breaker.

In accordance with the invention, an electric circuit interrupter is provided of the current-limiting type including an arc-establishing means and assembly of arc filter and muffle means comprises an assembly of spaced metallic plates providing intimate contact between the plates and the arc gases for cooling purposes, in addition to diffusing action for avoiding the creation of a reflected shock wave, plus expansion chambers for extracting energy from the arc gases as well as for cancelling or diminishing sound and shock wave forces of various frequencies, all as disclosed and described in detail in the aforesaid copending patent application. In addition, there is provided, in accordance with the present invention, are muffle lining and sealing means comprising a generally rectangular sleeve of elastomeric material surrounding the arc muffle assembly and overlapping a portion of the arc establishing means. In accordance with another aspect of the invention, an integral inwardly extending circumferential rib is provided in the resilient sleeve, extending into a corresponding circumferentially extending space provided at the juncture of the arc muffle and the arc-creating means which inwardly extending rib acts as a valve portion to flatten out and seal against the entry of gases at this point between the arc-creating means and the sleeve and thence to the outside of the assembly.

The invention will be more lowing detailed description, in the appended claims.

in the drawings,

FIG. 1 is a side elevation view of an electric circuit interrupting device incorporating the invention, a portion of the sidewall thereof being removed to show the internal construction;

FIG. 2 is a schematic representation of the circuit through a complete circuit breaker of one type incorporating the invention;

FIG. 3 is a top plan view of a three-pole circuit-interrupting device including an arc-extinguishing means and an arc discharge filter assembly constructed in accordance with the invention;

fully understood from the foland its scope will be pointed out FIG. 4 is a side elevation view of the three-pole arc-extinguishing means and one discharge filter assembly of FIG. 3;

FIG. 5 is an end elevation view of the threepole arc-extinguishing means and are discharge filter assembly of FIG. 3 and 4;

FIG. 6 is an exploded perspective view of a precooler pori'on of the arc discharge filter assembly of the circuit interrupter assembly of FIG. 1;

FIG. 7 is an exploded perspective view of the are discharge filter and muflie assembly of the device of FIG. 1;

FIG. 8 is a partially exploded perspective view of the parts utilized in the cooler assembly portion of the arc discharge filter and mufile assembly of the device of FIG. 1, and

FIG. 9 is a perspective view of an arc muffle liner member constructed in accordance with the invention, a portion thereof being broken away to reveal aspects of the internal construction.

In the drawings, the invention is shown as incorporated in a three-pole electric circuit breaker or interrupter. As shown in diagrammatic form in FIG. 2, each pole of the interrupter comprises an arc-extinguishing section 10, a movable contact operating means 11, and are gas discharge filter or muffle" assembly 12.

Referring now to FIGS. 1 and 2, the arc establishing and extinguishing portion 10 of the interrupter comprises a pair of spaced, angularly disposed stationary contacts 13 and 14, mounted on a pair of outwardly diverging arc runners l5 and 16 respectively, which terminate in arc anchor tips 17 and 18, respectively.

A generally wedge-shaped movable contact assembly 20 is also provided having a pair of contact members or contact surface portions 21, 22 thereon disposed at an angle to each other for cooperating with the stationary contacts 13 and 14 respectively. The movable contact member 20 is connected by a contact operating rod 24 to the plunger 25 ofa solenoid 26 (see FIG. 2).

The solenoid 26 is connected electrically in series with a first blowout coil 27, the stationary and movable contact assembly, a second blowout coil 28, and then to an output terminal 29. The other end of the solenoid 26 is connected to an input terminal 30.

Blowout coils

27, 28 are not shown in FIG. 1, but may be positioned adjacent the contact assembly and provided with magnetic pole pieces which concentrate the magnetic flux across the path of the arc to assist acceleration of the arc in its elongating direction.

The circuit breaker also includes means for manually moving the movable contact assembly between open and closed circuit positions and for retaining it in the closed-circuit position in such a way that when the solenoid 26 is energized, the movable contact member may be pulled to the open condition despite the retention of the operating handle in its on position. For this purpose, there is provided a mechanism which may take any desired one of a number of different forms. For the purpose of illustration, a simplified operating mechanism is shown connected to the contact operating rod 24 and comprising an operating link 32 pivotally supported on a fixed pivot 33, and having an elongated slot 34 therein receiving a pin 35 carried by the rod 24. An operating handle 36 is supported for arcuate movement between on" and off positions as shown, and a tension spring 37 is connected between the operating handle 36 and the pin 32A.

The handle 36 may be supported for arcuate movement in the manner described by any suitable means, such, for example, as being supported in an arcuate track, not shown, in insulating sidewall members, not shown. Alternatively, the handle 36 may be supported on a rigid generally U-shaped handle support member, not shown, having its pivot point below the link 32, and substantially in vertical alignment with the pin 33.

It will be observed that when the operating handle 36 its moved from off" osition to on," the line of action of the spring 37 passes across the pin 33, and biases the operating link 32 in counterclockwise direction, moving the operating rod 24 to the right, moving the movable contact assembly to closed position. When the parts in the closed circuit position, the bias of the spring 37 urges the movable contact to its closed position providing contact pressure between the movable contacts 21, 22 and the corresponding stationary contacts 13, 14. When the parts are in this condition, if a short circuit occurs in the line connected to the circuit breaker and excessive current flows therethrough, the solenoid 26 increases its pull on the plunger 25, pulling the contact operating rod 24 and the movable contact assembly 20 to the left as viewed. This action causes the link 32 to rotate in clockwise direction, regardless of whether the operating handle 36 is forcibly restrained in the on" position or not. If desired, the dimensions and proportions of the parts may be arranged so that when the movable contact rod moves to open-circuit position, the line of action of the spring 37 will have passed across the pivot pin 33, thereby causing the link 32 to remain in open-circuit position if the handle member 36 is not forcibly restrained, thereby moving of the handle member back toward off position. A mechanism suitable for use with the invention is shown and described in greater detail in application Ser. No. 457,557 filed May 21, 1965 and assigned to the same assignee as the present invention, now abandoned and replaced by application Ser. No. 768,963, filed Oct. 10, 1968, and by application 866,083, filed Oct. 3, 1969.

As the movable contact assembly 20 moves to open position, a pair of short arcs, not shown, are drawn between the movable contact 21 and the stationary contact 13 and between the movable contact 22 and the stationary contact 14, respectively. These two short arcs are immediately transformed into a single longer arc extending between the stationary contacts l3, 14, as indicated in FIG. 1. This are is thereupon moved by its own magnetic motoring action, supplemented by the magnetic blowout force of the

coils

27, 28 and by the force of arc gases, outwardly along the

arc runners

15, 16.

When the arc is created and elongated in the manner described at extremely high speeds as required for true current-limiting action, high pressures are generated within the arc-extinguishing chamber 38. The circuit interrupter includes an exit baffle member 39 extending across the outlet portion of the arc chamber 38, having two sets 39A, 39B, of angularly diverging slots therein for permitting controlled venting of the gas from the circuit interrupter per se. The temperature and speed of arc gases emerging from the openings 39A, 39B of the baffle 39 are extremely high, and of such a nature as to be intolerable in situations in which personnel may be nearby at the time of a short circuit interruption or where the breaker must be located near an object which might be damaged by such hot gases.

A combined arc discharge filter and noise and flame muffle assembly is provided which effectively eliminates the objectionable expelled flame and hot gases and greatly reduces the noise generated by the interruption process.

Referring first to FIG. 3, the arc discharge filter or flame and noise mufile of the invention includes a generally rectangular boxlike heavy metallic enclosure 40 having opposed

sidewalls

41, 42, and a pair of

intermediate barrier walls

43, 44, dividing the general enclosure into three

compartments

45, 46, 47. The enclosure 40 also includes an integral end wall 65, having a plurality of rectangular apertures 66 therein. Each of the

chambers

45, 46, 47, contains arc discharge and filter apparatus all of which are similar, and therefore the structure of the apparatus contained in only one chamber, i.e., chamber 47, will be described, it being understood that the

chambers

45, 46, also contain comparable structure.

Referring now to FIG. 4, the chamber 47 is divided by longitudinal barrier means comprising barriers 49A and 49B and 49C together with intermediate barrier portion 50A of the insulator block 50 to be described into two parallel elongated generally

rectangular chambers

47A and 478. Each of the longitudinal portions 47A, 47B of the chamber 47 contains similar arc discharge filter and muffle structure, and therefore the parts contained in only the lower portion 478 will be described, reference being had for this purpose to the lower portion of FIG. 1.

As indicated in FIG. I, the portion 478 of the arc discharge filter and muffle assembly includes five (5) serially related chambers or portions. These portions are as follows: l) a precooler" or preliminary heat exchange portion 51, (2) a combination first expansion chamber and reflective wave dispersing or diffusion means 52, (3) a first cooler portion 53, (4) a second expansion and diffusion chamber 54, and (5) a final cooler chamber portion 55. The construction and assembly of the parts contained in these chambers will now be described in detail with reference to the exploded views FIGS. 6 and 7.

Referring to FIGS. 6 and 7, the precooler" portion 51 comprises a pair of supporting plates 57 supporting a plurality of spaced, stacked, relatively short metallic plates 58A. Adjacent each of the plates 58A except the end plates, and preferably in side-to-side contact therewith, is a second, longer plate 588 having an angularly bent end portion 588'. This combination provides plates which are of substantial thickness and therefore of substantial heat-absorbing capacity throughout their major portion, and deflector portions which extend into the adjacent expansion chamber 52 while occupying only a minimum amount of the space in the expansion chamber. The plates 58A, 58B, are spaced and arranged so that the spaces between these plates are in alignment with the spaces 393 in the bafile member 39.

The construction of the first cooler portion 53 is shown in exploded FIG. 7, and also in detail in FIG. 8. Each of the assemblies 53 includes a series of metallic plates 60 having a large number of small holes 61 therein. The metallic plates 60 are maintained in close spaced relation by insulating spacer members 62 each comprising a generally rectangular frame portion 62A and an intermediate portion 628. The spacer members 62 are constructed of any suitable insulating material having the ability to withstand high temperatures. In a preferred form of the invention, the insulating spacer 62 comprises an impregnated cellulosic fiber known as vulcanized fiber.

Adjacent metallic plates 60 have the holes 61 therein offset or staggered with respect to the holes 61 in each of the adjacent plates. As a result, there is no continuous straight line path for gases through the assembly of plates 53. The assembly of plates 60 and spacers 62 is retained in assembled relation primarily by means of the cooperation of the adjacent parts and the fact that all of such parts are closely fitted within the corresponding chamber of the generally boxlike enclosure 40, and maintained therein by the retaining relationship of the barrier 39. For the purpose of facilitating handling and assembly, however, the plates 60, 62 may be retained temporarily in assembled relation by means of nonconductive adhesive strips 63.

The second expansion chamber 54 is formed by two chambers 54C and 54D of an insulating block 50. The insulating block 50 is preferably constructed of insulating material having the characteristics of high heat withstanding ability and substantial strength. A suitable material for example has been found to be glass fiber filled alkyd or melamine plastic.

In FIG. 9 there is shown a modified form of second expansion chamber means 54. In this form of the invention,

expansion chambers

54A, 54B, 54C, and 54D are provided by a pair of generally U-shaped metallic members 74 and 75 respectively. These pieces interfit in such a manner that their upturned leg portions 74A, 74B and 75A, 75B, together with the intermediate partition member 50A, form the dividing partition and end walls of the aforesaid chambers. In this form, the walls are constructed of metallic material for further helping to extract energy from the arc gases. As previously mentioned, because this location is so remote from the point of initiation of the arc, there is no danger of arc strikeover at this point.

The final cooler assembly 55 is constructed in the same manner as the preliminary cooler 53 previously described, but preferably includes fewer plates.

As shown in FIGS; 1, 7, and 9, there is provided, in accordance with the invention, for each arc mufile assembly, an elongated generally rectangular sleeve of elastomeric material, preferably silicone rubber. The sleeve 67 of the first pole is illustrated in detail in FIG. 9 and also shown in FIGS. 1 and 7. As indicated in these figures, the sleeve also includes an integral inwardly extending circumferential rib 69 spaced inwardly from one end thereof. As shown in FIG. 1, the rib 69 extends inwardly a short distance between the arc baffle member 39 of the arc establishing assembly and the preliminary heat exchange and diffuser assembly 51. The plates 58A, 58B, of the assembly 51 are notched slightly, as are the supporting side plates 57 thereof so that even with the rib 69 extending between these two assemblies, the edges of the plates 58A, 58B are in substantially direct contact with the corresponding surface of the arc baffle member 39.

In addition, the silicone sleeve 67 is provided with a first vertically extending group of three holes 73, and a pair of lon-' gitudinally spaced holes 74, 75, all of which permit the passage of insulating tubes 70 having clamping screws or bolts 71A extending therethrough for clamping the parts together as described. The dimensioning of the

holes

73, 74, 75 in the silicone sleeve 67 is such that they provide a close seal around the insulating tubes 70. In addition, further scaling is provided by the use of a small amount of plastic sealing putty such as silicone putty 76, in the corner or crack between the inner end of the sleeve 67 and the inner surface of the arc baffle member 39, (see FIG. 1).

On the occurrence of extremely high pressures, such as during the interruption of a high short circuit current, gases under pressure are contained and prevented from escaping to the exterior by a path other than through the arc muffle assembly by the action of the silicone sleeve 67 which acts in a manner of a valve to distort and better seat against the adjoining surfaces to prevent the entrance of gas. Referring to FIG. I, and secondarily, to FIG. 7, it will be observed that the precooler" or preliminary heat-exchange portion 51 and the expansion chamber 52 of the muffle assembly do not present a substantial impeding medium to the flow of gases, even at high speed. The cooler portion 53, however, and the cooler portion 55, do present a substantial impedance to high-speed (explosive nature) flow of gases. As described hereinbefore, there are no straight, line-of-slight continuous paths through the portion 53, or through the portion 55. As a result, there is high pressure in the chambers 52, 53 during the initial portion of a short circuit current interruption. This pressure is ultimately relieved through the

portions

53, 54, 55 of the arc muffle assembly, but a finite amount of time, however shon, is required for this to occur.

Meanwhile, since the pressure in chambers 51, 52 is high, it attempts to escape by all possible paths. One such path, in the absence of the structure of our invention, would be between the outer periphery of the baffle block 39 and the outer enclosure, in a direction from right to left as viewed in FIG. 1. This is a particularly dangerous path since the gases in the chamber 51,52 are still highly ionized, and if they could escape and reach a grounded part, a fault or "strikeover" would result, since the distance from such grounded part to either of the stationary contacts is comparatively short.

To shut off this path, the space between the baffle assembly 39 and the enclosure 40 is filled with a portion of the integral silicone sleeve 67 as shown. Moreover, as previously mentioned, the sleeve 67 has an integral inwardly directed flange or lip 69 which overlies the entry to the crack between the baffle member 39 and the inner surface of the sleeve 67. The effect of this lip is to act as a valve which, under pressure from the chambers 51, 52, is pressed tightly against the corresponding front surface of the baffle 39, sealing the crack between it and the sleeve 67. In addition since this member is constructed of inorganic material, it cannot carbonize or release objectionable gases, such as to cause oversurface breakdown or loss of dielectric strength.

It will be understood that a separate sleeve or liner is used for each of the muffle assemblies for each of the

pole chambers

45, 46, 47.

In assembly, the discharge filter and mufile parts are first assembled into the silicone sleeve 67 to form an assembly as shown in the upper portion of fig. 7. This subassembly is then inserted into the corresponding chamber of the enclosure 40 and anchored therein by the rods 70 and bolts 71A. The barrier block 39 is retained in place by cross pins or insulated bolts such as bolts 71A, 71B, covered by insulating tubes 70, with suitable retaining means, not shown, at each end.

The

sidewalls

41, 42 and the

intermediate walls

43, 44 of the enclosure 40 are extended at the arc extinguisher end of the assembly, and provide means for anchoring and assembling the insulating blocks 72 forming the enclosure for the arc initiation and extinguishing portions.

The operation of the device will now be discussed. It should be understood that while considerable advances in the knowledge of the behavior and methods of control of arcs in gaseous media are continually being made, as witnessed by the aforementioned patent application 457,557 assigned to the same assignee as the present invention, the subject is by no means completely understood in all its ramifications. The same is generally true of the subject matter of arc discharge filter and muffle designs, and perhaps even more so of the interrelation and cooperation of these two components. The following observations are based, however, upon numerous experiments and tests in which the apparatus described above has been found to be exceedingly effective. Accordingly, while the particular mechanisms or phenomena operating in the device may not be completely understood, the following is the best present interpretation of the inventor as to the functioning of the apparatus in achieving desirable results attained.

It is believed that the preliminary heat exchange portion 51 functions to extract a substantial amount of heat from the incandescent gases emerging from the barrier member 39 as these gases are forced to pass in close contact with the relatively cold metallic surface of the plates. This action may descriptively be referred to as a scrubbing" action, and causes an important decrease in the energy of the arc gases. The efficiency or efficacy of this action is critically related to the spacing between adjacent walls of the plates 58A, 58B, which is another reason why the thickness of these plates is made greater at their main body portion.

The outer ends of the plates 58B are directed at an angle to the main portion or fanned primarily to prevent occurrence of a reflected-back pressure wave which might otherwise be reflected from the surface of the first of the plates 60 of the assembly 53. In addition, these diverging portions or diffusers" introduce a desirable turbulence at this point causing the cooler portions of the gas, which have been cooled by contact with metallic plates 58A, 588, to mix with the remaining gases and more equally distribute the heat.

The divider 49, and particularly the divider portion 49A, prevents the arc from striking across, either at the beginning or at the ends of the plates 58A, 58B. It will be observed that in order for an arc to strike across through this part of the are extinguishing assembly with the present construction, it would have to extend, from the stationary contact 17, through at least one of the slots 39A, to the spaces between the plates 58A, 58B, around the ends of these plates, toward the divider plate 49A, thence back through one of the spaces between the plates 58A, 588, through another one of the slots 39A, then back through one of the slots 39B, and through a similar path between the plates 58A, 588 in the lower section, around the ends of the plates in this section, to and finally back through another one of the slots 398 to the stationary contact 18. Such a path would be so long that its total voltage drop would far exceed the voltage drop being maintained in the arc directly between the stationary contacts 17 and 18 at the surface of the insulating block 39. If the conditions are being considered as they exist immediately after the extinction of the are between the contacts 17, 18, the voltage of such an alternate parallel path could be so high as to exceed the voltage required to break down directly between the stationary contacts 17, 18.

The are gases are forced through the assemblies 53 previously described comprising a series of spaced metal plates 60 having a large number of relatively small holes 61 therein and maintained in closely spaced relation by the insulating spacers 62. As previously noted, the holes 61 in these plates are not in exact alignment, so that there is no path straight through this assembly of plates. The hot gases are therefore forced into contact with the metallic material of the plates at a great many points, since as the jets of gas emerge through the openings in any one particular plate they immediately impinge against the metallic material of the next adjacent plate. Because of the spacing between adjacent plates, a degree of turbulence is created which causes intermixing of the incandescent gases and accelerates and improves the cooling.

The spacers 62 may be constructed of any desirable insulating material which is capable of withstanding the heat created by the arc. If desired, the spacer 62 may be constructed of metallic material, since at this stage of the arc-extinguishing assembly, an arc path of adequate length is provided in any case, and there would be no danger of strikeover, it being noted that the lower assembly 53 is divided from the upper assembly 53 by the barrier plate 498.

The block 54 provides a total of four expansion chambers therein, as shown particularly in FIG. 7, 54A, 54B, 54C, and 54D. These chambers are made of substantial length as compared to the spaces between the plates 60, for the purpose creating further turbulence and for removing or filtering out relatively low-frequency shock and sound waves (the filter assemblies 53, on the other hand, with the relatively close spacing of the plates 60 serve to remove, damp, or reduce the relatively high-frequency shock and sound waves). A series of four of such chambers are provided, rather than one or two continuous large chambers in order to adjust the volume of each of the chambers to the size best suited to cancel or reduce the frequencies in the lower range desired to be eliminated by this section. The final section 55 is similar to the previous section 53 and serves to further reduce the noise, flame, and shock wave. In addition, the presence of the final section 55 is believed to be desirable in connection with obtaining the proper action from the expansion chambers 54.

in accordance with another aspect of the invention, the enclosure 40 provides a separate casing or enclosure for each of the poles of the circuit breaker. As previously described, the enclosure 40 preferably comprises a single integral box having an end wall 65 with a series of generally rectangular openings 66 therein, see HO. 5. Each of the openings 66 corresponds in area to the cross-sectional area of one of the

expansion chambers

54A, 54B, 54C, 54D. Thus the outlet opening area of the assembly is not decreased by the end wall 65, but nevertheless the end wall 65 serves to provide a substantial support in this direction to prevent the parts from blowing outwardly under the pressure of the arc gases. In addition, the fact that the sidewalls of the container 40 which extend perpendicular to the bottom wall are all integrally interconnected, and this assembly is reinforced and held together by a number of transversely extending assembly bolts 71. These comprise a series of three main bolts 71A disposed along the longitudinal center line of the assembly, and a series of additional bolts 718 adjacent the arc-initiating chamber.

The are discharge filter and muffle assembly of the invention has been found highly effective in reducing the noise, shock wave, and flame emitted from a high-pressure circuit interrupter. While it has not been possible to obtain specific comparative data on the magnitude of the reduction, it is believed that a conservative estimate in reduction of the force of the sound and shock wave is in the order of 1,000 to l By means of the invention, an electric circuit interrupter is provided which has relatively small size compared to extremely high-capacity interruption ability. For example, the embodiment illustrated provides a circuit interrupter having a normal current-carrying rating of amperes at 600 volts, and is capable of interrupting the short circuit current created by a system which has the capability of delivering over l00,000 amperes. The outer dimensions of this circuit breaker, including the arc filter and discharge and muffle portions is approxi mately 17 inches long and 4% by 4% inches cross section. Prior to the development of applicant's present invention, there was no circuit breaker capable of performing a currentlimiting interruption on a circuit of this magnitude. The dimensions of a prior art noncurrent-limiting circuit breaker which were of a type which would be required to be used in circuits having these power capabilities are as follows: 33 inches long, with a cross-sectional area of approximately 27 by 25 inches, giving a total volume over 60 times as great as the breaker of the present invention.

While the invention has been disclosed in one particular embodiment, it will be apparent that many modifications thereof may readily be made without departing from the spirit and scope of the invention. It is accordingly intended by the appended claims to point out the particular areas considered to comprise the essence of applicant's novel and useful contribution to the art and to cover all such modifications as fall within the true spirit and scope of the invention.

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

1. An electric circuit interrupter comprising:

a. an arc establishing and interrupting means including a pair of diverging arc runners, means for creating an are between said are runners at their closely adjacent end portions, means for moving said are outwardly along said runners toward the widely spaced ends thereof in a first general predetermined direction, and insulating means supporting and enclosing said outwardly diverging arc runners and constraining gases generated by said are to move away from said arc runners in the aforesaid predetermined direction, said insulating means forming an arc-extinguishing chamber having a generally rectangular arc-gas venting portion;

b. arc-gas discharge filter and mufi'le means supported in juxtaposed relation to said arc-extinguishing chamber and in line with said arc-gas venting portion in said predetermined direction, said arc discharge filter and mufile means having a generally rectangular cross section conforming substantially to said venting portion of said areextinguishing means, and having openings therein for receiving said are gases and having venting openings at the opposite end thereof for discharging said are gases;

c. a generally rectangular sealing sleeve of an elastomeric material closely surrounding said arc-gas discharge filter and muffle means and at least a portion of said arc-interrupting means and bridging the juncture therebetween;

d. said sleeve including an integral circumferentially inwardly extending rib portion extending inwardly between said arc-interrupting means and said arc-gas discharge filter and muffle means;

e. an outer enclosure of rigid material surrounding said sleeve at the outer sides thereof; and

f. said rib acting to prevent the escape of arc gases from a location adjacent said juncture along the inner surface of said sleeve in a direction opposite to said first direction to a location outside of said arc-extinguishing chamber and outside of said arc-gas discharge filter and muffle means relatively close to said widely spaced ends of said are runners such as might cause a strike-over or fault.

2. An electric circuit interrupter as set forth in claim 1 wherein said sleeve is composed of silicone rubber.

3. An electric circuit interrupter as set forth in claim 1 wherein said sleeve also includes a plurality of openings therethrough, and said interrupter also includes insulated fastening means extending through said openings transversely of said sleeve for holding said interrupter together despite high gas pressures therein, said openings being dimensioned with respect to said insulating fastening means to provide a tight gas-sealing engagement therewith.

4. A multipole circuit interrupter comprising:

a. a plurality of side-by-side arc establishing and interrupting means, there being one such arc establishing and interrupting means for each pole of said multipole circuit interru ter; a plura lty of arc-gas filter and muffie means, there bemg one such arc-gas filter and muffle means for each of said arc establishing and interrupting means; and

c. a single, generally boxlike sheet metallic enclosure closely enclosing all of said arc establishing and interrupting means and all of said arc-gas filter and muffle means, said metallic enclosure having a first pair of opposed sidewalls and a second pair of opposed sidewalls extending perpendicular to said first pair of said sidewalls and an end wall extending perpendicular to all of said sidewalls, said end wall having a plurality of openings therein through which are gases may vent to the exterior of said circuit interrupter.

5. An electric circuit interrupter as set forth in claim 4 wherein said enclosure has barriers forming a plurality of chambers therein corresponding in number to the poles of said multipole circuit interrupter, each of said chambers containing one of said arc establishing and interrupting means and a corresponding one of said arc-gas filter and mufile means.

6. An electric circuit interrupter as set forth in claim 5 wherein said circuit interrupter also includes a sleeve of elastomeric material lining each of said chambers of said multichamber enclosure and serving to contain said gases and to constrain the flow of said are gases through said arc-gas filter and muffle assemblies and through said openings in said end wall of said enclosure.

Claims

1. An electric circuit interrupter comprising: a. an arc establishing and interrupting means including a pair of diverging arc runners, means for creating an arc between said arc runners at their closely adjacent end portions, means for moving said arc outwardly along said runners toward the widely spaced ends thereof in a first general predetermined direction, and insulating means supporting and enclosing said outwardly diverging arc runners and constraining gases generated by said arc to move away from said arc runners in the aforesaid predetermined direction, said insulating means forming an arc-extinguishing chamber having a generally rectangular arc-gas venting portion; b. arc-gas discharge filter and muffle means supported in juxtaposed relation to said arc-extinguishing chamber and in line with said arc-gas venting portion in said predetermined direction, said arc discharge filter and muffle means having a generally rectangular cross section conforming substantially to said venting portion of said arc-extinguishing means, and having openings therein for receiving said arc gases and having venting openings at the opposite end thereof for discharging said arc gases; c. a generally rectangular sealing sleeve of an elastomeric material closely surrounding said arc-gas discharge filter and muffle means and at least a portion of said arc-interrupting means and bridging the juncture therebetween; d. said sleeve including an integral circumferentially inwardly extending rib portion extending inwardly between said arcinterrupting means and said arc-gas discharge filter and muffle means; e. an outer enclosure of rigid material surrounding said sleeve at the outer sides thereof; and f. said rib acting to prevent the escape of arc gases from a location adjacent said juncture along the inner surface of said sleeve in a direction opposite to said first direction to a location outside of said arc-extinguishing chamber and outside of said arc-gas discharge filter and muffle means relatively close to said widely spaced ends of said arc runners such as might cause a strike-over or fault.

4. A multipole circuit interrupter comprising: a. a plurality of side-by-side arc establishing and interrupting means, there being one such arc establishing and interrupting means for each pole of said multipole circuit interrupter; b. a plurality of arc-gas filter and muffle means, there being one such arc-gas filter and muffle means for each of said arc establishing and interrupting means; and c. a single, generally boxlike sheet metallic enclosure closely enclosing all of said arc establishing and interrupting means and all of said arc-gas filter and muffle means, said metallic enclosure having a first pair of opposed sidewalls and a second pair of opposed sidewalls extending perpendicular to said first pair of said sidewalls and an end wall extending perpendicular to all of said sidewalls, said end wall having a plurality of openings therein through which arc gases may vent to the exterior of said circuit interrupter.

5. An electric circuit interrupter as set forth in claim 4 wherein said enclosure has barriers forming a plurality of chambers therein corresponding in number to the poles of said multipole circuit interrupter, each of said chambers containing one of said arc establishing and interrupting means and a corresponding one of said arc-gas filter and muffle means.

6. An electric circuit interrupter as set forth in claim 5 wherein said circuit interrupter also includes a sleeve of elastomeric material lining each of said chambers of said multichamber enclosure and serving to contain said gases and to constrain the flow of said arc gases through said arc-gas filter and muffle assemblies and through said openings in said end wall of said enclosure.