US3177324A

US3177324A - Circuit breaker employing perforated arc runners

Info

Publication number: US3177324A
Application number: US162303A
Authority: US
Inventors: Eugene W Boehne
Original assignee: Allis Chalmers Corp
Current assignee: Allis Chalmers Corp
Priority date: 1961-12-01
Filing date: 1961-12-01
Publication date: 1965-04-06
Anticipated expiration: 1982-04-06

Description

April 6, 1965 E. w. BOEHNE 3,177,324

CIRCUIT BREAKER EMPLOYING PERFORATED ARC RUNNERS Filed Dec. 1, 1961 3 Sheets-Shee'c. 1

April 6, 1965 E. W. BOEHNE Filed Dec. l. 1961 CIRCUIT BREAKER EMPLOYING PERFORATED ARC RUNNERS 5 Sheets-Sheet 2 April 6, 1965 E. w. BQ'EHNE 3,177,324

CIRCUIT BREAKER EMPLOYING PERFORATED ARC RUNNERS Filed Dec. 1, 1961 3 Sheets-Sheet 3 CPP/77nd Kazaa/7) a9 7 @99 Cf/1g. M

United States Patent 3,177,324 CIRCUIT BREAKER EMPLOYING PERFORATED ARC RUNNERS Eugene W. Buehne, Villanova, Pa., assigner `to Allis- Chalmers Manufacturing Company, Milwaukee, Wis. Filed Dec. 1, 196i, Ser. No. l62,3tl3 4 Claims. (Cl. 21m-144) This invention relates to electric circuit interrupting devices and is a continuation in part of application S.N. 681,259, filed August 30, 1957, by Eugene W. Boehne entitled, Circuit Breaker Employing Perforated Arc Runners.

It has been known for some time that arc vapor is one of the worst enemies in the performance of alternating or direct current circuit breakers. Vaporized metal in the arc stream tends to maintain and stabilize the arc thus hindering its interruption. In view of the fact that the metallic contents of the arc stream depend principally upon metal vapors or particles derived from the arc runners, it is important that the ends of the arc in Contact with the arc runners be kept moving continuously in order to avoid heat concentrations and the consequent high vaporizing action. Inasmuch as arcs effect a vaporizing action of the materials used in the construction of an arc extinguishing device and since such vaporization tends to cause reignition of the arc at the contacts, resulting in failure to interrupt the arc at an early current zero, and restriking of the arc at the exhaust end of the arc chute, it is desirable to not only control the amount of metallic vapors but also its movement through the arc chute structure.

In accordance with the invention claimed, a new and improved compact circuit breaker structure is provided comprising a pair of relatively movable contacts, means for drawing an arc between the contacts, an arc chute for receiving the arc at one end thereof and exhausting the arc products at the other end, a chimney vent and an are runner arranged adjacent the contacts for providing a conductive path for the terminal of the arc from the contacts into the arc chute. The arc runner comprises one wall of the chimney vent and is perforated for providing an inlet into the chimney vent from the arcing zone whereby the metallic vapors generated by the arc terminal moving along a part of the outside surface of the chimney vent are expelled through the vent to atmosphere:

It is, therefore, one object of the present invention to provide a new and improved arc interrupting device.

Another object of this invention is to provide a new and improved arc interrupting device in which the metallic vapors generated by the arc terminals are expelled through the arc runners to atmosphere.

A further object of this invention is to provide a new and improved arc interrupting device in which the arc terminals are provided with a predetermined path along the arc runners.

A still further object of this invention is to provide a new and improved arc interrupting device in which the arc runners are perforated in a predetermined manner for controlling exhaustion to atmosphere of metallic vapors issuing therefrom.

A still further object of this invention is to provide a new and improved arc extinguishing device in which the arc runners are perforated and ribbed in a predetermined manner to control the movement of the arc terminals thereover and the metallic vapor emission therefrom.

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

FIG. 1 is a view in vertical cross section of a magnetic blowout type of circuit breaker employing the present invention;

3,177,324 Patented Apr. 6, 1955 FIG. 2 is an enlarged perspective partial View of one of the arc runners illustrated in FIG. l;

FIG. 3 is a cross sectional view through the contact structure of FIG. 1 taken along the line lll-III;

FIG. 4 is an enlarged perspective partial view of a modication of the arc runners illustrated in FIGS. l and FIG. 5 is a chart graphically illustrating the cooling effects of the claimed arc runner versus a solid arc runner;

FIGS. 6, 8, and 10 illustrate an arc runner employing an axially disposed continuous wide slot, an arc runner employing an axially disposed, continuous narrow slot and one formed of the claimed apertured arc runner structure, respectively; and

FIGS. 7, 9 and ll illustrate graphically the velocity distribution curves of the structures shown in FIGS. 6, 8 and 10, respectively.

Referring more particularly to the drawings by characters of reference, FIG. 1 illustrates a magnetic blowout type of circuit breaker employing an arc chute into which the arc is forced by the magnetic blowout field and extinguished. The power circuit to be interrupted includes relatively movable contacts between which the arc is formed when the contacts separate at the entrance to the arc chute. Specifically, the contacts comprise a fixed contact structure l1 and a coacting movable contact structure l2. The fixed Contact structure is electrically connected to a lead in conductor stud 13 defining one terminal of the breaker, and the movable contact structure i2 cornprising a pivoted switch arm having an arcing Contact mounted at one end thereof is electrically connected to a conductor stud l5 defining the other breaker terminal. The pivoted Contact structure l2 is suitably operated between open and closed circuit positions by an operating rod 16 that is connected through a crank 17 to a solenoid or other operating means 18.

FIG. l illustrates the movable contact structure l2 in contact open position, the coacting main and arcing

contacts

20, and 22, respectively, of the movable contact structure l2 being spaced apart from corresponding main and arcing contacts 23 and 25, respectively, of the fixed contact structure il. A pair of lugs 2l (one of which is shown in FIG. l) is integrated with arcing contact 22 and extends from opposite sides of a web portion of arcing contact 22. Lugs 2l together with the web portion of the arcing contact 22 form an engaging surface which coacts with that of a block of insulating material 24 on the stationary contact structure l1 to limit overtravel of the movable contact structure 12 in the closing direction. in breaker closed position the stationary arcing contact 25 is shunted by stationary main contact 23. Opening of the breaker by the clockwise rotation of the breaker movable contact structure 12 causes, in the sequence named, separation of the rnain current carrying contacts 2t), 23 and the arcing contacts 22, 2S. The power arc is formed at the entrance of an arc chute 26.

Arc chute 26 is illustrated as being provided with magnetic blowout means comprising

blowout coils

23 and 29 arranged so as to cause the arc formed between the contacts 22 and Z5 to be blown by the magnetic field into arc chute 26. Blowout coil 2S is connected at one end thereof to a conductive arc runner 3i? and at the other end thereof immediately adjacent main contact 23. Blowout coil 29 is connected at one end thereof to a conductive arc runner 31 and at the other end thereof to a lower terminal extension 3.2 through a conductive bar 27.

Upon separation of the arcing contacts 22. and 25 in a circuit interrupting action the arc terminal is transferred from stationary arcing contact 25 to arc runner 36, thereby inserting blowout coil 28 in the arcing circuit traced from the point of connection of blowout coil 28 on the upper terminal block immediately adjacent main contact c 23 through blowout coil to arc runner 3?, through the arc to movable arcing contact Z2. As the are, now established between arc runner Stil and the movable arcing contact 22, is attenuated by the clockwise rotation of contact 'structure l2, the arc envelops the lowermost portion of arc runner 3l thereby transferring the arc terminal from arcing contact 22 to arc runner 3l and inserting blowout coil 29 in the arcing circuit. The arcing circuit is now completed through the bar 27 which connects the blowout coil 29 with the lower terminal extension 32.

Referring more particularly to the movable contact structure l2 of one phase of a three phase circuit breaker, as shown in FGS. l and 3 of the drawings, the switch arm comprises a pair of spaced plates 35 (one of which is shown in FlG. l) mounted on a pivot bolt The spaced plates 3S are also interconnected by a pin 37 which serves to connect the switch arm to the operating rod llo. Secured to the plates 3S and mounted on bolt 3e with the spaced plates 35 is a pair of spaced plates 3S. Plates 38 extend generally parallel along the inside surfaces of plates 35 and are joined to plates 35 by any suitable means such as rivets di). Plates 38 are joined together at their outer extremity by the contact body or head forming the current carrying contact Ztl and the arcing contact 22.

Arranged between the

spaced plates

35 and 38 is a hollow uid conducing stationary bearing 39 for the reciprocating switch arm or movable contact structure i2. This bearing may be made of any suitable material, such as cast bronze, suflciently strong to withstand the shock of circuit breaker operations.

Bearing 39, more particularly, is arranged between conducting extensions 32 on bolt 3o.

Spaced plates combinations

35, 38 are yieldingly biasedV toward each other and against the opposite sides of bearing 39 by any suitable means which, for example, may be spring washers 33 secured to bolt 36 by a nut 3d. Washers 33 are held in stressed condition against the sidesV of spaced members 35 by -bolt 36 and nut 34, thus providing high contact pressure. Conducting ring inserts il are provided between plates 38 and conducting extensions 32 to provide a line contact between the stationary and movable parts of this hinge connection. Bolt 36 which passes through suitable openings provided in spaced

members

35, 38, extensions 32 and bearing 39, is provided with a closely iitting collar or shield 42 which serves to form a substantially fluid tight connection between the hollow opening in bearing It@ and the bolt 36.

The arcing contact structure and the arc chute of the circuit breaker structure are mounted on a supporting structure comprising a fabricated vehicular base structure d5. Mounted on base structure l5 is the circuit breaker operator ld which may be a solenoid, pneumatic, or a pneumo-hydraulic type of circuit breaker movable contact actuating means. A pair of dual purpose substantially vertical or diagonal tubular members lo (one of which is shown in FIG. l) are provided on base structure 4:35. Members i6 4are connected to a horizontally arranged manifold 49 which supports a pair of horizontal cross bracing means i7 (only one of which is shown in FlG. l). The circuit breaker elements comprising the movable contact mechanism of the circuit breaker and the arc chute are mounted on the horizontal cross bracing means 47 and the manifold 49. Members te in addition to supporting the circuit breaker, further collect and distribute to a zone of arc initiation fluid under pressure from a source of fluid under pressure such as a suitable pneumatic means 48 used for aiding in cooling and extinguishing an arc drawn by the circuit breaker elements between the arcing contacts.

This pneumatic means may be an air pump comprising a cylinder Sil mounted on base structure 45 and a piston Ell movable in cylinder Piston Slt is biased in contact opening direction by an operating spring S9 which is the means for opening the circuit breaker. The pneumatic means 48 serves a plurality of functions, namely, it is the motor actuating means for opening the contact of the circuit breaker, it acts `as an air pump to force air through the bearing 39 and nozzle 53 to aid in cooling and extinguishing the arc, and it acts as a shock absorber to retard the movement of the switch arm near the end of its opening stroke to reduce the impact of the movable contact structure l2, through operating rod ld, on the fixed structure of the circuit breaker. The solenoid operating means 18 through crank 17 returns piston 5l to its contact closed position simultaneously with a circuit breaker closing operation', thereby compressing spring 59 so it is capable of again opening the circuit breaker contacts. Any suitable means such as lpipe connections 52 may be used for connecting the substantially vertically arrangedY tubular members lo to the source of fluid under pressure, namely cylinders Sti.

Manifold 49 is connected to the bearing 39 of each wtich arm of each phase of the three phase circuit breaker through insulating tubular members 54. Bearing 39 comprising a hollow cylindrical member is provided with an outlet 55 (more clearly shown in FIG. 3), A slip ring 56 having attached thereto an insulating tubular member 57 of high dielectric and fiashover strength or a suitable metallic member rwhich terminates at its outer end in a nozzle 58 arranged adjacent the breaker contacts in the zone of arc initiation is mounted around trunnion 39. Tubular member 57 is attached to the switch arm for movement therewith. As shown in FIG. 1,tubular member 57 is generally arranged parallel with the switch arm in a predetermined relationship with the

contacts

20 and 22. Slip ring 56 is arranged to provide a passageway for air under pressure from cylinder Sti through tubular member do, manifold 49, tubular member-54, bearing 39, tubular member 57 and nozzle 58 to the zone of arc initiation. Tubular member 57 and nozzle 58 are secured to spaced plates 3S so that slip ring 56 and nozzle 5t) move concurrently with plates 33 upon actuation of the aroing contacts to circuit open or circuit closed position.

For the punpose of aiding in thek interrupting of the arc the switch arm or movable contact structure l2 is connected to piston Sil through operating rod 16, crank 17 and a piston rod 60. Upon the movement of contact structure 12 from closed to open circuit position under the action of springs 59, piston Sil is actuated and moved from the top of cylinder Si) to the bottom of cylinder 50.

This movement of piston 5l causes air in cylinder 5b under piston 5l to flow through pipe connections 52, tubular member d6, manifold 49, tubular member 54,

bearing 39,' tubularV member 57 and nozzle 58 to the zone of arc initiation.

Arc chute 26 is provided with a group of slotted,

Vspaced insulating plates 62 arranged to extend longitudinally of Ithe axis of the chute and transversely to the are at the arc receiving end thereof and a pair of chimney vents 63 and 64 arranged longitudinally of theV axis of the chute one adjacent each of the arc runners 3@ and 3l. The insulating barrier plates 62 may be arranged in Ya combination having a plurality of types of barrier plates the shortest possible arc length. With the knowledge that Y the level of are voltage isggreatly diminished by the presence of metal vapors a new and improved arc runner is provided which reduces the metal vapor content of the main arc column through the arc chuterof the circuitV breaker structure.

Therefore, in accordance with the invention claimed, the gases containing the metal vapors created at least in part by the arc terminals are bled or exhausted to atmosphere through chimney vents 63 and 64. The arc runners comprise at least a part of the wall or outer surface of chimney vents 63 and 64 so that the arc terminals actually travel over the outside surface of the vents as they move along the arc runers. In order to capture immediately the arc vapors generated by the arc terminals the arc runners are perforated. As shown in FIGS. 1 and 2 the arc runners are provided with a plurality of apertures 65 which may be arranged, for example, along their length to provide a passage through the arc runners and into the chimney vent. These apertures may extend along the full length of the arc runner, along only a part thereof, or along only that part of the arc runner arranged downstream of the upstream edge of barrier plates 62.

As noted from FIG. 2 of the drawing apertures 65 are spaced at random along arc runner 30 but any predetermined arrangement of these apertures may be used if so desired.

FIG. 3 illustrates in detail the switch contact arm fluid conducting bearing means.

FIG. 4 illustrates a modification of the arc runners shown in FIGS. 1 and 2 wherein a rib or bead 66 is arranged on an arc runner 67 or formed integrally therewith. Arc runner 67 as in FIGS. 1 and 2 forms one side or wall of a flue means 68 which may be arranged in the arc chute 26 in the manner disclosed under the discussion of FIGS. 1 and 2. This bead extends along at least a part of the longitudinal length of the arc runner and in FIG, 4 is shown as extending along the center `of the contact enga-ging surface of runner 67 with apertures arranged along the length of the are runner in a random manner on either or both sides of rib 66. It is intended, however, to come within the scope of this invention t-o use any form of apertures, the arc runner having a rib or bead extending any place along its arc terminal engaging surface. The rib or bead provides a track along which the arc lterminal travels by preference as the arc is repelled upwardly by the blowout coils 28 and 29 and prevents random tracking of the are terminal and its consequent seizure upon the edges of the perforations.

When the arcing contacts 11 and 12 are separated to draw an arc, the arc terminals move 4from the contacts to the arc runners. The arc terminals are forced along the arc runners by the magnetic effect of the arc and coils 28 and 29 and also the chimney effect of the arc chute. The arc causes an internal pressure within the circuit breaker structure which acts to drive the gases created by the arc out all possible exits. By providing suitable exit in the arc runner itself in the form of holes or apertures the metallic vapors so generated are forced to exhaust out separate channels such as chimney vents 63 and 64 almost as soon as they are generated.

The interruption of high voltage alternating currents of large magnitude such as, 4for example, 50,000 amperes, by air magnetic circuit breakers invoives transient phenomena of little more than one-half cycle (one current loop) duration. Obviously, therefore, the severity of the interrupting duty imposed on such breakers by currents of large magnitude will depend to a considerable degree upon the point of time on the current wave at which the circuit breaker arcing contacts initially separate.

When the arcing contacts separate after current zero and on the increment of the current loop the time interval required for transfer o-f the arc from the arcing contacts to the arc runners and thence by the magnetic blowout action to the arc exinguishing portion of the arc chute is such that the arc usually burns in that portion of the arc chute only throughout the decrement of the current loop and is permanently extinguished at the subsequent current zero.

However, if the arcing contacts separate on the decrement of a current loop the conditions will be essentially as shown in FIG. 1, wherein the arci-ng contacts separate on the decrement of the current loop at time T1, the arc transfers to the arc runners at A-A prior to current zero time T2, is selfaextinguished at current zero time T2, reignites immediately thereafter at B-B, and is driven by the magnetic blowout action into the extinguishing portion of the arc chute at C--C where it burns for a substantial period of time prior to time T3 and then throughout the interval T3-T4. Under these conditions a 50,000 ampere arc must be permanently extinguished at the current zero time T4 if the possibility of damage to the breaker is to be avoided.

The conditions that frequently obtain in the region of the arc runners when a 50,000 ampere arc burns in the arc extinguishing portion of the arc chute throughout the crest interval of a current loop are essentially the same as those `described in U.S. Patent 2,904,659 to E. W. Boehme, column 6, first paragraph, beginning line 14. As shown in FIG. 1 of this disclosure the arc will restrike repeatedly on the arc run-ner, as at :point D, with the arc terminal repeatedly retracing a path along the surface of the arc runner from the point D to the point C.

At currents of 50,000 amperes such restrikes recur with great rapidity thereby generating metallic vapors on the arc runners which are expelled with explosive violence according to an article written by J, D. Cobine and E. E. Burger entitled, Analysis of Electrode Phenomena in the High-Current Arc, published in Ithe Journal of Applied Physics, volume 26, number 7, dated July 1955. The explosive violence suggests very high `local pressures at the point of origin of the metallic vapors.

Because of simultaneous, opposing high arc gas pressure within the arc chute, the blasts, or surges, of metallic vapor so generated will tend to escape upwardly along the arc runner to atmosphere at the exhaust end of the arc chute. However, experience has demonstrated that external flashover will occur unless this upward surge of metallic vapor is effectively damped. Conversely, the smaller the amount of metallic vapor permitted to escape freely at the exhaust end of the arc chute the greater the amount that will be impelled into the space at the intake end of the arc chute at the next current zero and thereby the greater the tendency for reignition of the arc. Y

It is the purpose of this invention, arc runner forms one of the walls to minimize the adverse effect on the arc interrupting function of such essential critical damping of metallic vapor `surges at the exhaust end of the arc chute.

Because the metallic vapor is generated in rapidly recurring blasts or surges yit will be subjected to a succession of extremely high pressure peaks. Each of these pressure peaks will impel a portion of the metallic vapor into land through the constricting perforations thereby creating a condition of extreme turbulence immediately achacent the exposed and relatively cold surface of the arc runner 1ndicated in FlG. 2. Such extreme turbulence will have a marked cooling effect on the metallic vapor remnant. The metallic vapor which is impelled through the constrioting perforations will be cooled by its own turbulence and by diffusion in the chimney vent.

wherein a perforated of a chimney vent,

In FIG. 5 the vaporization temperature 3000 K. is the round number equivalent of the experimental value of 29.20 K., for copper, given in Table II, page 897 of the ;Cob1ne and Burger paper and the temperature 1000 K. 1s approximately that at which metallic vapor becomes a relatively poor conductor.

FIG. 5 graphically demonstrates :the elfect of the claimed invention on the arc extinguishing function of the circuit breaker by comparing it with a similar circuit breaker structure having a solid arc runner. It is to be understood FIG. 5 depicts a comparison of the performance of the for purposes of illustration that the graph in atrasos perforated arc runner shown in FIG. l with that of a solid arc runner Where the latter is similar in construction, except as to perforations, and is employed in a similar circuit breaker structure. It is to be further understood, however, that arnangements other than as shown in FIG. l such, for example, as that shown in FIG. 4 could similarly be utilized to illustrate the comparison shown in FIG. 5.

It is characteristic of the arc extinguishing function of an air magnetic circuit breaker that the arc gas pressure within the are chute declines very rapidly as the are current approaches zero. Hence, near current zero metallic vapors confined adjacent the arc runners by that arc gas pressure will rapidly expand and diffuse in the lower portion of the arc chute. Whether the arc is permanently extinguished or whether it reignites or restrikes after the current zero will depend on the temperature as well as on the volume of the metallic vapor diffusing in the arc chute.

The solid arc runner which, creating little or no turbulence, has no appreciable cooling effect on the metallic vapor within the time equivalent of one current loop. If the metallic vapor generated at this solid runner must diffuse therefrom into the arc chute a distance O-D of FIG. 5 before itis cooled to the substantially nonconducting temperature of l000 K., then the temperature gradient may be represented by the line A-D of FIG. 5.

Assuming lall other conditions to be exactly the same, let the solid arc runner be replaced by the claimed perforated arc runner in the disclosed structure. The cooling elect of the claimed runner reduces the temperaturek of the metallic vapor during the vaporization phase from B to C and the line drawn from C parallel to A-D represents the corresponding temperature gradient and its point of intersection D' with line O-D indicates the distance that the metallic vapor will diliuse from the claimed perforated arc runner into the arc chute before the metallic vapor becomes substantially nonconducting.

The dotted line A-D' is indicative of the degree to which a temperature gradient based on the initial temperature of 3000 K. will be depressed by lche cooling effect of the claimed structure.

Obviously, both O-D and O-D are critical distances and must be kept substantially less than half the distance between the vertical portions of the arc runners if reignitions and restrikes in the lower portion of the arc chute are to be avoided.

The cool-ing effect on the metallic vapors is created by the turbulent escape of the metallic vapors through the perfor-ations of the arcrunner into the chimney vent. Thus diversion and isolation of substantial amounts of metallic vapor from the main vapor body is simultaneous with the cooling action on the vapor of the arc stream.

To comprehend the benefits of apertured arc runners over slotted arc runners includ-ing the narrow-slotted type disclosed in .the arc runners 53 and 47 of FIG. 1 of the Nau U.S. Patent 2,276,859 and slots 39 in the

arcing plates

55 and 63 of the Ludwig et al. U.S. Patent 21,243,- 040, a few fundamental principles must be recognized. In a steady flow of gas the liow velocity is greatest where the cross sectional area is the least. The laws of friction are very different for low and high flow velocities. Where the flow velocity is low, liow resistance is proportional to the iirst power of the velocity, however, where the velocity is high, ow resistance is approximately proportional to the square of the velocity. The change from the irst power law to the second power law occurs suddenly at a critical velocity which depends upon the nature of the gas, the geometrical conguration of Ithe gas conduit and the material of which the conduit is made. The change from the iirst power law to the second power law occurs in any given gas for any given structure always at the same critical velocity. If that velocity is exceeded, eddies are formed in which the motion of the gas is circular. Circular motion is one of the characteristics of turbulent gas flow. Turbulence occurring in the arcing chamber of air blast breakers markedly increases the rate of deionization.

Since a rapid ow of gas is decelerated close to the boundary between its ow and a gas layer of lesser iiow velocity, the liow velocity is zero at the boundary between a rapid gas iiow and a fixed wall. Gases iiowing through passages have zero velocity at the boundary surface between the gas and the walls of the passage. Maximum gas velocity is reached along an axis situated midway between opposite boundary surfaces of the gas flow.

FIGS. 6 through ll show the manner in which metallic vapors generated on the arc runners of an air magnetic circuit breaker will react to escape means through. the arc runner. FIG. 6 is particularly directed to an axially disposed, continuous wide slot 7S in an arc runner '76, FlG. 8 Iis particularly directed to an axially disposed, continuous narrow slot 77 in an arc runner 73, and FIG. 10 is particularly directed tothe perforated arc runner of the type disclosed and claimed herein.

In the case of arc runner '76 having a continuous Wide slot '7S as shown in FIG. 6 constriction of the escaping metallic vapors vby the slot is of a low order. The peak velocity V1 of the metallic vapors as shown in FIG. 7 is so far below the critical velocity that turbulence is negligible and the metallic vapors will escape with substantially undiminished energy into and through the chimney vent unless trapped and effectively deenergized therein.

In the case of arc runner 78 having a continuous nar-V row slot 77, illustrated in FIG. 8 and shown and defined above in the Nau and Ludwig et al., patents, the boundary surfaces of the slot (where the metallic vapor velocity is always zero) are brought into close proximity to each other, whereby the resistance of these boundary surfaces virtu ally blocks the flow of metallic vapor through the narrow slot. The velocity distribution curve VD2 of FIG. 9 shows this condition and the peak velocity V2.

In the case of the claimed Yapertured arc runner 79, as shown in FIG. l0, constriction of the escaping metallic vapors by the perforations Sii is of a relatively high Vorder.

The metallic vapors are accelerated to a peak velocity of Y V3 shown in FiG. ll by the velocity distribution curve V2 which exceeds :the critical velocity thereby creating the condition of extremeturbuience adjacent the relatively cool arc runner surface that effectively cools and deionizes the metallic v.fapors as they ,escape through the perfor-ations and into the chimney vents.

It is possible with the new and improved structure claimed herein to cool, deicnize and exhaust the metallic vapors at Vthe' point of generationrandrthereby provide effective conditions Vfor circuit interruption in'asrnall compact circuit breaker structure. This new and improved structure is adaptable for both alternating and directeurrent interruption. V

Although but a few embodiments of the present invention have been illustrated and described, it will be apparent Y 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.

Having now particularly described and ascertained the nature of my said invention and the manner in which it is to be performed, I declare that what I claim is:

l. An electric circuit interrupter comprising a pair of relatively movable contacts, means for drawing an arc between said contacts, an arc chute for receiving the arc at one end thereof and exhausting the arc products at the other end, a chimney vent, any arc runner arranged adjacent said contacts for providing a conductive path for a terminal of the arc from said contacts into said chute, said arc runner comprising one wall of said vent and being provided with a plurality of constricting apertures for creating a condition of extreme turbulence extending therel through'along at least a part of the length thereof for providing a plurality of inletsto said vent whereby metaloutside of said vent are expelled through said vent to atmosphere, and rib means arranged 0n said arc runner to extend longitudinally thereof between some of said apertures for providing a track along which the arc terminal may travel as the arc moves through said chute.

2. An electric circuit interrupter comprising a pair of relatively movable contacts, means for drawing an arc between said contacts, an arc chute for receiving the arc at one end thereof and exhausting the arc products at the other end, said chute comprising a chimney vent, a magnetic coil arranged adjacent said contacts for driving the arc into said chute, and an arc runner comprising at least a part of the outer surface of said vent for providing a conductive path for a terminal of the arc from said contacts into said chute, said arc runner being wrapped around at least a part of said coil and extending downstream therefrom to a position within the entrance end of said chute, said part of said arc runner extending Within said chute and comprising a part of said vent being provided with a plurality of circular constricting apertures for creating a condition of extreme turbulence extending therethrough whereby the metallic vapors generated by the arc terminal are expelled through said apertures and into said vent.

3. An electric circuit interrupter comprising a pair of relatively movable contactsmeans for drawing an arc between said contacts, an arc chute for receiving the arc at one end thereof and exhausting the arc products at the other end, said chute comprising a pair of chimney vents, a pair of spaced are runners one fbeing arranged adjacent each of said contacts for providing a conductive path for the terminals of the arc from said contacts into said chute, said arc runners each comprising an outer surface of a dierent one of said vents and each being provided with a plurality of circularconstricting apertures for creating a condition of extreme turbulence extending therethrough l@ for providing a plurality of inlets into said vents whereby the metallic vapors generated by the arc terminals are expelled through said vents to atmosphere, and rib means arranged on each of said arc runners to extend longitudinally thereof between some of said apertures for providing a track along which the arc terminals may travel as the arc moves through said chute.

4. An electric circuit interrupter comprising a pair of relatively movable contacts, means for drawing an arc between said contacts, an arc chute for receiving the arc at one end thereof and exhausting the arc pro-ducts at the other end, a chimney vent for conducting the arc products through said chute, and an arc runner arranged adjacent said contacts for providing a conductive path for a terminal of the arc lfrom said contacts into said chute, said arc runner comprising one wall of said vent and being provided with a plurality of circular constricting perforations creat-ing a condition of extreme turbulence extending therethrough, whereby metallic vapors generated by the arc terminal are expelled through said vent to atmosphere.

References Cited bythe Examiner UNITED STATES PATENTS 2,243,040 5/41 Ludwig et al 200-149 2,259,005 10/41 Scott 200-147 2,276,859 3/42 Nau 200-147 2,740,021 3/56 Frink 200-144 2,889,433 6/ 59 Kozlovic et al. 200-147 2,953,666 9/ 60 Matthias 200-147 FOREIGN PATENTS 100,792 8/23 Switzerland.

BERNARD A. GILHEANY, Primary Examiner.

. ROBERT K. SCHAEFER, Examiner.

Claims

1. AN ELECTRIC CIRCUIT INTERRUPTER COMPRISING A PAIR OF RELATIVELY MOVABLE CONTACTS, MEANS FOR DRAWING AN ARC BETWEEN SAID CONTACTS, AN ARC CHUTE FOR RECEIVING THE ARC AT ONE END THEREOF AND EXHAUSTING THE ARC PRODUCTS AT THE OTHER END, A CHIMNEY VENT, AN ARC RUNNER ARRANGED ADJACENT SAID CONTACTS FOR PROVIDING A CONDUCTIVE PATH FOR A TERMINAL OF THE ARC FROM SAID CONTACTS INTO SAID CHUTE, SAID ARC RUNNER COMPRISING ONE WALL OF SAID VENT AND BEING PROVIDED WITH A PLURALITH OF CONSTRICTING APERTURES FOR CREATING A CONDITION OF EXTREME TURBULENCE EXTENDING THERETHROUGH ALONG AT LEAST A PART OF THE LENGTH THEREOF FOR PROVIDING A PLURALITY OF INLETS TO SAID VENT WHEREBY METALLIC VAPORS GENERATED BY THE ARC TERMINAL MOVING ALONG THE OUTSIDE OF SAID VENT ARE EXPELLED THROUGH SAID VENT TO ATMOSPHERE, AND RIB MEANS ARRANGED ON SAID ARC RUNNER TO EXTEND LONGITUDINALLY THEREOF BETWEEN SOME OF SAID APERTURES FOR PROVIDING A TRACK ALONG WHICH THE ARC TERMINAL MAY TRAVEL AS THE ARC MOVES THROUGH SAID CHUTE.