US2359800A - Fluid blast circuit breaker - Google Patents

Description

Oct. 10, 1944. w. M. scoT-r, JR-

FLUID BLAST CIRCUIT BREAKER INVENTOR wwaammswvnh Oct. 10, 1944. w. M. sco'rT, .JR 2,359,300

FLUID BLAST CIRCUIT BREAKER Filed Dec. 11, 1940 7 sheets-sheet 2 IN VENTOR.

ATTORNEY.

w. M. SCOTT, JR 2,359,800

FLUID BLAST CIRCUIT BREAKER Filed Deo. 11,v y1940 7 sheets-sheet s INVENTOR JILSWVLJ Oct. 10, 1944.

ATTORNEY.

Oct. 1o, 1944. W, M SCOTT, JR 2,359,800

FLUID BLAST CIRCUIT BREAKER Filed De@ ll, 1940 7 Sl'leebS-Slleei 4 INVENTOR.

Oct. 10, 1944.

7 Sheets-Sheet 5 W. M. SCOTT, JR

FLUID BLAST CIRCUIT BREAKER Filed Deo. l1, 1940 ATTORNEY.

FLUID BLAST CIRCUIT BREAKER ATTORNEY.

w. M. SCOTT, JR 2,359,800

FLUID BLAST CIRCUIT BREAKER Y Filed Dec. l1, 1940 '7 Sheets-Sheet 7 INVENTOR, v m. SM1. @La/ ATTORNEY.

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Patented Oct. 10, 1944 FLUID BLAST CIRCUIT BREAKER William M. Scott, Jr., Bryn Mawr, Pa., assgnor to I. T. E. Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application December 11, 1940, Serial No. 369,572

(Cl. 20o-148) 29 Claims.

My invention relates in general to the field oi circuit interrupting devices, but more specifically relates to a novel and improved design for a huid blast circuit breaker, and its associated arcing chamber.

In all alternating current circuit breakers with contacts separating in a surrounding fluid, the arc current is carried through ionized fluid which forms a relatively low resistance path. This path is maintained ionized or incandescent by heat generated by the flow' of the current therethrough. When in the course of its Cycle, the current wave passes through zero, heat generation stops. The arc path retains heat for a period of time depending upon the rate at which heat is removed. To establish normal insulation between the contacts, the temperature in this space must be reduced below a critical value.

During the interruption of a fault current, the current and voltage pass through zero at different moments. In general, the voltage will have passed through zero and be increasing in value at the instant that the current value reaches zero. Therefore, there is a substantial voltage across the contacts as the current reverses its direction. If the chilling of the surrounding medium has not been completed, the voltage will be sufilcient to break down the partly cooled fluid and permit a resumption of current flow.

This problem of establishing normal insulation in the space between the contacts becomes more dilncult to solve as the line voltage increases.

To decrease the arcing time and hence to reduce the damage to the contacts, it is therefore advantageous to replace the arc products with a stream of high dielectric strength at a ratewhich will prevent breakdown between the contacts due to the recovery voltage.

The air blast circuit breaker is a device in which these principles are applied. The contacts are separated in a chamber into which a blast of air is introduced to cool the arc and to remove the arc products at a rate which will prevent breakdown after the first current zero has been reached.

Prior air blast breakers'have had several inherent disadvantages which tend to decrease the effectiveness and increase the cost of operation thereof.

The typical circuit breaker requires frequent renewal of arcing contacts or arcing horns. The' breaker must be disconnected from the line for contact inspection and the expense of new contacts is often incurred.

The burning action of the extremely high temperature arc during the period of opening is the cause of contact deterioration and as a result, the contacts become rough, pitted and scarred and add considerable electrical resistance to the circuit due to improper Contact. To successfully extinguish the arc and to minimize the destructive action upon the contacts, the arc terminals should be kept in continuous motion and cooled, and the gas in the arcing chamber deionized. In addition, the ionized gas formed by the arc should be removed from the arcing chamber as rapidly as possible to prevent the voltage, which is rapidly recovering between the contacts after current zero, from reestablishing the arc.

The arcing chamber in which the foregoing is accomplished is usually traversed by an air blast to accomplish the required result. The air iiowing across the contacts should be utilized to cool the arc sufliciently to prevent its reestablishment with the rising voltage of the next current half cycle.

The principle of the arcing horn, which is employed in many of the present day devices, is that the arc will be transferred'either by magnetic elds or by an air blast, from the contacts to a gap between two horns where the entire energy will be spent Without deleterious effects upon the contacts. Here again, as in the arcing contacts, the horns deteriorate and frequent renewal becomes an undesirable feature.

If, however, the arc is not allowed to remain in a single position, but instead is maintained in continuous motion, the effects at any particular pointon the contacts would be negligible. That is, the deleterious efects of the arc upon the contacts are dependent upon the maximum temperature of the contact. This will depend upon the number of amperes iiowing and the time during winch the arc terminal remains concentrated on any particular point of the contact.

My invention contemplates an arcing chamber wherein the arc is lengthened and broken into a series of shorter arcs which are maintained in rapid motion across cooling plates while under the influence of a cooling and deionizing blast.

More specifically, I have. designed an arcing chamber for an air blast breaker which comprises a laminated structure of metallic and insulating plates having a cylindrical opening therein to permit the operation of a cooperating pair of cylindrical contacts therethrough.

As the contacts separate, the arc that isdrawn therebetween is transferred to the inner surfaces of plates composing the laminated structure, the

transfer being facilitated by the novel contacts which I have devised. Alternate layers of metal and insulating material serve to divide the arc into a series of shorter arcs, in circuit with each other. Each of these arcs is under the influence of a blast of air which enters through nozzles formed in the walls of the metallic structure and which exhausts through similar ports.

The arcing chamber is designed so that the individual arcs are acted upon by this high velocity air blast in a manner best adapted for rapid deionization without any tendency kfor blowing the arc out of the chamber. The air inlet nozzles are oriented to cause an air vortex plates housing the nozzle construction serve to The insu-V lating barriers interposed between the metallicy cause the individual arcs to be struck across the air inlets and not at the discharge openings,

Oil, or any other highly insulating fluid may, of

course, be utilized instead of air, with the arcing chamber of my invention. Under these circumstances, the viscosities and specific heats of the different fluids must be considered in the breaker design, but these factors merely necessitate a variation in the dimensions of the intake and discharge openings rather than change in the principle of operation. Also, if oil or any other inflammable medium is employed, means must be provided for eliminating a fire hazard. That is, the contacts must at all times be submerged in the fluid to preclude the presence of air.

It is therefore an object of my invention to provide a fiuid blast circuit interrupter of novel design which may be easily and economically manufactured and which possesses a high interrupting capacity.

It is another object of my invention to provide a fluid blast circuit breaker in which the arc terminals on the contacts are maintained in motion by a high velocity blast to preclude the possibility of incandescent points being produced.

A further object of my invention is .to provide an arcing chamber in which the arc is broken up into a series of shorter arcs, each of which is continuously subjected to a cross blast of air to facilitate cooling and deionization.

Another object of this invention is to provide an arcing chamber comprising a stack of metal plates insulated from each other and arranged so that the arc may be transferred thereto and cooled by a blast of air.

Still a further object of this invention is to provide a novel form of contact which will facilitate the transfer of the arc to a series of metal plates.

Another object of my invention is to provide an arcing chamber into which air is supplied through a series of nozzles oriented to cause an air vortex surrounding the faces of the contacts.

It is an additional object of my invention to provide an arcing chamber, for an air blast circuit breaker, in which one of the contacts moves in a piston-like manner, drawing an arc and progressively opening air ports through which the arc quenching air flows.

It is still a further object of my invention to provide an arcing chamber for an air blast circuit |breaker in which the contacts are separated in a piston-like manner and in which the arc that is drawn is spun at a high velocity and in which there is no tendency to blow the arc'from the chamber. y

These objects and others will become evident detail the construction of the contacts and the 4air blast manifold or inlet to the arcing chamber taken along the line 4-4 of Figure 2.

Figure 5 is a cross-sectional View of the arcing chamber and the air manifold taken along the line 5--5 of Figure 2 Figure 6 is a sectional view taken along the line 6 6 of Figure 4 and specifically illustrates the details of the nozzle arrangement of the air inlet.

Figure 7 is a cross-sectional View of the arcing chamber taken along the line 1--1 of Figure 4 to indicate the design of the discharge chamber or air outlet.

Figure 8 is a broken perspective view of the stack which forms the arcing chamber to indicate the air flow therein.

Figure 9 is a broken cross-sectional view schematically illustrating a modified form of contact arrangement. y

Figure 10 is a cross-sectional view of contact plunger and latch taken along the line I-IIJ of Figure 9, during the closing movements.

Referring now to Figure l, the arcing chamber of my invention is shown in connection with a representative schematically drawn air blast circuit breaker assembly.

The mechanical linkage used to close the contacts and .the overcurrent and manual tripping mechanisms are not shown, but it will become evident that the conventional trip-free or other suitable linkages may be employed as required for the particular application of the circuit breaker.

The external circuit is connected to the contacts of the circuit breaker, Which is herein illustrated as a single pole unit, through the bus bars or studs Il and I2, and this circuit is interrupted when required by the separation of the contacts within the arcing chamber I3.

Air under pressure from an external compressor and storage means is delivered to the circuit breaker through the automatically operated valve I4, which may be a balanced valve, controlled by an electro-magnetic device contained Within the housing,

The valve I4 which is interposed between the storage tank and the circuit breaker is joined to the air supply by suitable piping at I6 and to the circuit breaker piping at II. A T-shaped coupling 23 serves to divide the air stream and has one branch 24 connected to .the air supply by means of the pipe 25 leading to the control valve I4.

IAnother branch 26 of the T connection 23 is joined to the pipe 21 and leads to the circuit breaker contact release mechanism contained Within ythe housing 32. Here again suitable piping is installed to best adapt the breaker to the particular application and in this embodiment comprises the pipes 21, 33 of insulating material, and 34 between which continuity is established by the 90 piping elbows 35 and 3B.

Thus, air is delivered to the chamber within the housingr 32 through the piping member 34 which is screwed into a tapped perforation 30 in the housing wall.

The third branch 43 of the T-shaped coupling 23 permits air flow to the arcing chamber I3 through the pipe 44 and the inlet head 45 of the air blast chamber.

The insulating` connector 44 is proportioned to withstand weight of the elements it supports, the force of contact engagement and the like.

The inside diameters of the insulating connector 44 and the various other piping connections will be determined by the capacity of the breaker, that is, the amount of air required to perform the distinct circuit interrupting opera. tions such as deionization and release of the latching mechanism. The control elements are supported by insulators 48 from the circuit breaker mounting bracket 46, which is herein illustrated schematically as a metal channel suitably formed and perforated to allow the passage of the pipes.

Thus the air circuit originating at the entrance I 6 to the control valve I4 is divided and ccmprises two circuits, one of which leads to the arcing and deionizing chamber and the other to the tripping mechanism. Obviously. therefore, energization of the control device I will actuate valve I4 to simultaneously admit air to both the arcing chamber and contact tripping mechanism. Accordingly, the contacts contained within the arcing chamber I3 will be immersed in a blast of air as will hereinafter be described, at

the instant that separation begins following the operation of the latch releasing mechanism.

The details of the arcing chamber are illustrated in Figures 4 and 5.

The two cylindrical contacts 5I and 52 are mounted so that they may be brought into engagement in a piston-like manner to contact each other along the surfaces 53 and 54.

The motion of contact 5I is relatively short Whereas contact 52 is mounted upon a plunger 55, which is operated either manually or automatically to provide the full contact separation between the two. The contact carrying plunger 55 projects from the arcing chamber at 55 as illustrated in Figure 1 and extends therefrom sufficiently to accommodate the mounting of the manual operating mechanism and to permit engagement with the latch I1 of the pneumatic tripping device contained in the housing 32.

As previously mentioned, the plunger 55 carrying contact 52 may be connected mechanically to a hand lever for mechanical actuation thereof to permit the establishment of the circuit. This mechanical linkage may be made trip-free to prevent the contacts of the circuit breaker from being held closed during undesirable circuit conditions.

The contact opening mechanism is so arranged as continuously to bias the rod 55 to move contact 52 to the open circuit position. This may be accomplished by means of suitable tension or compression springs connected betweenv rod 55 and the frame of the circuit breaker.

As illustrated in Figures 1, 4 and 5, the rod 55 has been withdrawn from the arcing charnber and accordingly the electrical circuit has been broken. To close the circuit, it is necessary to vmove the rod 55 against its biasing spring (not Cil illustrated) so that the face of contact 52 engages thatof contact 5I and forces it back into its housing against the bias of spring 6I as will be described in a later paragraph.

Rod 55 slides freely within two cylindrical bearings. lOne bearing 62 is an integral part of the terminal assembly 63 and the other bearing 64 is associated with the latch mechanism and fastened to the frame of the circuit breaker assembly. Therefore, the bearings 62 and 64 define the path of movement of the plunger 55 and its associated contact 52 as axial piston-like displacements.

A releasable latch mounted in tbe support for bearing.r 64 is used to hold the contacts in full engagement against the bias of spring 6I and that of the plunger opening spring. Inasmuch as the rod 55 is continuously biased toward the open circuit position, release of this latch will result in opening movement. This movement, however, is limited by means of the shoulder 68 on rod 55 which engages in the open position the annular metal stop 61, through which the reduced diameter of the rod 55 passes.

This shoulder will limit the motion of rod 55 in the direction of its spring bias, to the position where it engages the face 'I3 of the stop 61, and hence is formed in rod 55 at a point predetermined to allow the contact 52 to be completely withdrawn from the arcing chamber I3, as shown in Figures 4 and 5.

Inasmuch as the motion of the rod 55 to its open circuit position after release may be eX- tremely rapid and under the influence of powerful springs', means are provided to absorb the kinetic energy of rod 55 without causing undue shock. Numerous schemes may be employed. 'In the example shown, the stop 6'I which arrests this motion, has been mounted upon the frame of the circuit breaker through the cushion 'E5 which may be of rubber or any other resilient shock absorbing material. The cushion is annularly formed, similar to the stop El, but the inner cylindrical opening 14 is greater than the outer diameter of the rod 55, to preclude possibilty of frictional contact between the cushion and the rod, which would tend to decrease the speed of contact separation.

The tripping mechanism illustrated in Figure 1 is automatically operated from the same source of air as is the deionization chamber. This mechanism comprises a housing 32 in which a cylindrical chamber I5 has been formed slidably fitting within this chamber is a piston I6 supporting a piston rod 'I1 which comprises the latch for either releasing or engaging the contact plunger 55.

The latch 'I1 projects through the upper portion 9| of thepneumatic chamber through the perforation 92 which serves as a guide therefor, and constrains the movement thereof to linear displacements parallel to the axis of the cylinder.

Piston 'I5 and its associated latch 'II are actuated by means of the compressed air supplied to the upper portion 82 of the chamber through the piping connection 34. Under the influence of this incoming air, piston 'IE moves downward against the action of the spring 83 which biases the latch 'I'I toward the contact carrying rod 55. This spring 83 is continuously under compression and is supported by the frame 84 of the circuit breaker mounting and may be contained within the lower portion of theV air chamber 15, and joined to the frame 84 through an adjustable support, making it possible to adjust the pressure required to operate the latch.

The upward movement of the piston 16 is limited by the shoulder 86 formed in the upper portion of the air chamber by reducing the diameter of the upper portion of the chamber. Hence, the outer edge of the piston 16 will engage the shoulder 8G to determine the maximum upward movement of the piston under the influence of the spring 83.

As illustrated in Figure 1, the valve I4 is in its open position and is admitting air under pressure to the upper portion of the chamber 82 through the inlet 34. Accordingly, the piston 16 has been displaced to its adjustable stop against the action of compression spring 83, and it should be noted that the wedge shaped portion 81 of the latch '|'I has been drawn clear of the edge 88 of the rod 55.

When operating the plunger 55 to engage the contacts 5| and 52 and complete the circuit, the air confined within the chamber 82 is at atmospheric pressure and accordingly the pis-v ton 16 is biased upwards by the spring 83 so that the upper corner of the latch 'I'I is in contact with the lower edge of the contact carrying rod 55, and will slide along the edge 88 of the rod until the notch IUI passes over the face of the latch, when the spring 83 will cause the latch to move into the notch and engage the rod 55.

The notch I! has been cut into the rod 55 to ycorrespond with the wedge shaped portion of the latch TI. The engaging surface |02 of thenotch is ground smooth along with the leading surface |83 of the latch 'I'l so that disengagement of the two surfaces may be effected with a minimum of frictional restraining force therebetween.

When the circuit is closed, face |03 is in surface contact with face |92, contact being maintained as previously mentioned, by the compression spring 6| and the spring or other biasing means connected to the rod 55. If now a fault current causes the energization of the solenoid tripping device |55 or if it is actuated by means of an electrical circuit controlled by the operator, air will be admitted under pressure through the control valve I4, to start the blast of air through the inlet 44 to the arc extinguishing chamber I3 and simultaneously to the air cham,- ber 82.

The air pressure in the cylinder will force the piston 16 down against the force of the spring 83, and in so doing release the latch 'I1 from the notch HH. An air vent |04 is provided in the bottom of the cylinder '|5 to prevent the compression of air in this space from retarding the motion of the piston. 'I'he rod 55 will instantly be set in motion in the direction of its open circuit position under the action of the springs herein mentioned, and Icontact 52 will rapidly recede from contact 5I until the rod 55 has reached its final position as determined by the annular stop 61 and its associated cushion 65. An arc will be drawn within the deionization chamber which is traversed lby the air blast.

The embodiment of tripping mechanism herein described and illustrated is but one simple form of latch and I do not wish t0 be limited thereto. However, such a mechanism is advantageous in that the release of the contact `carrying plunger occurs simultaneously with the influx of air to the air blast chamber.

The arcing chamber I3 comlprises a stack of pairs of flat metal plates, each having a central opening to allow the passing of contact 52. Insulating barriers similarly perforated are interposed between these metal plates and the completed structure serves to conduct and discharge air to and from the central cylindrical chamber provided by these registering perforations. The air is supplied to this arcing chamber through two diametrically spaced cylindrical openings III and ||2 also formed in the deionizing stack by suitable registering perforations.

The nature of the chamber and its associated air ducts and insulating barriers which constitutes the most important phase of my invention will hereinafter be described in further detail; but reference has now been made thereto to better describe the arcing chamber auxiliary apparatus, which, it should be emphasized, need not be specifically limited to the embodiment schematically illustrated in the accompanying gures.

Referring again to Figure 1, the deionization chamber I3 is shown supported between the air blast inlet head 45 and the combined terminal and contact plunger bearing 63.

The air inlet head or manifold 45 is a metal casting and serves in the indicated structure as both a T-coupling for the air circuit and a support for the tubular housing of contact 5|.

Air is conducted to the head 45 from the T- coupling 23 through the pipe 44. The junction between the pipe 44 and the inlet head 45 is clearly illustrated in the cross-sectional View, Figure 4, the general view Figure 1, and the end sectional view of the inlet head, Figure 3. A hollow receptacle I I3 is an integral portion of the inlet manifold and has been tapped at |.|4 to engage a screw thread on the coupling pipe 44.

An annularly formed flange I I5 at the base of the receptacle I I3 limits the inward movement of the pipe 44, and perforation I I6 of diameter equal to the inside diameter of the pipe 44 permits the entry of air into the space ||8.

The pipe 44 is necessarily of an appropriate insulating material to electrically insulate the inlet air blast head 45 from the piping connections at the T coupling 23, inasmuch as the inlet head is at the electrical potential of -contact 5| and the piping connections are at ground potential.

As indicated in Figure 3, the space ||8 is, for the most part, an annularly shaped chamber contained between the walls |2I, |22, |23 and |24 of the casting and is of rectangular cross-section, except for the ducts |25 and |26, the function of which will be hereinafter described.

The perforation ||6 permits the entry of compressed air to the chamber I8 through the pipe 44. The air is guided through the chamber to the divergent openings |25 and |26 which are an integral portion of the inlet chamber casting.

Figure 3 more clearly illustrates the ring shaped chamber ||8 and the integral divergent passages |25 and |26 diametrically located to correspond with the air ducts ||I and I|2 of the deionization chamber as illustrated in Figure 5.

Thus the incoming air indicated by the arrowheads |3|, in Figure 4, passes through the perforation ||6 into the chamber ||8 where it is divided and conducted to the divergent openings |25 and |26 as indicated by the arrowheads |32 in Figure 5. The walls |33 and |34 of the divergent outlets I 25 and |26 as illustrated in Figures 3 and 5 are an integral'part of the chamber wall |2|, and are smoothed and curved to prevent excessive resistance to the air flow therein.

The inlet head or manifold 45 is rigidly secured against the deionization chamber I3 at the surfaces |35 and the openings` |25 and |26 are aligned with the air ducts and |1|2 of the arcing chamber. Also integral parts of the inlet head 45 are the diametrically opposite projecting lugs |36 and |31 shown in Figure 1 which are perforated to accommodate two bolts |4| and |42. The head |43 of the belt |4|, as illustrated in Figure 1, bears against the lug |36 through the lock Washer |44, and both bolts |4| and |42 pass through the stack comprising the deionization chamber through suitable holes therein, and through corresponding perforations in the terminal 63 to firmly clamp the assembled structure.

The terminal 63 is best illustrated in the end t sectional view, Figure 2, and in Figures 1, 4 and 5. This terminal is a casting preferablylof some highly conducting material such as copper and is composed principally of a flat plate of metal with a hollow cylindrical extension 62 which -serves as a sleeve bearing for the contact carrying rod 55.

The flat plate of the terminal 63 contains four semicircular projecting lugs |45, |46, |41 and |48 spaced at 90 intervals abouttheperiphery thereof. Diametrical projections |45 and |41 contains perforations |5| and |52 to accommodate the bolts |4| and |42 which securely bind together the inlet air blast head 45, the deionization stack |3 and the terminal 63. The nuts |53 and |54 bearing against the lock washers |55 and |56, cooperating with the bolts |4| and |42 serve to supply the necessary binding force and are herein illustrated as hexagonal machine screws and nuts.

When the circuit is opened, the inlet head 45 and the terminal 63 are at opposite electrical potentials and thus must be suitably insulated from each other as by the insulating sheets 302, the amount of insulation depending upon the magnitude of the voltage therebetween. The bolts |4I and |42 are made of an insulating material; dimensioned to withstand the mechanical stress developed therein.

The other diametrically spaced projections |46 and |48 function to seal the air ducts and4 ||2 as illustrated in Figures 2 and 5.

To secure the lead or bus bar |2 of the external circuit to the terminal 63, I provide a rectangular projection |1|, indicated in Figures 1, 2 and 4, which contains a plurality of tapped holes to receive an equal number of bolts |12 that pass through the bus bar I2 to rigidly support it upon the projection |1|.

An integral part of the terminal 63 is a hollow cylindrical extension 62 which serves as a bearing for the contact rod 65; However, the projection 62 is not merely a bearing that serves to guide the rod 55, but also acts as the conductive brush-like connection between the rectangular projection |1| on the terminal 6-3 and the contact rod 55. Thus the section |15 of this cylindrical bearing 62 provides a bearing surface at |16 to firmly but slidably engage the rod 55.

As illustrated in Figures 1 and 2, the longitudinal slots |11 are cut into the extension 62 to provide individual fingers |8| which are pressed firmly against the contact rod y55 by means of the garter springs |82 and |83, posi- .machined to provide `tioned in the circular grooves |84 and |85 turned into the outer surface of the sleeve 62. The flexible metal employed for the casting 63 under the influence of the spring pressure effects proper electrical contact between the terminal 63 and the contact plunger 55.

The garter springs |82 and |83 are continuous helices formed by fastening the ends of an ordinary spring, the length of which is predetermined to correspond with the circumference of the bearing 62 and provide the proper tension.

It is to be noted that the slots |11 extend nearly to the base of the casting while the Contact surface |16 begins at a distance from the bottom of the slots to provide a relatively long resilient arm and thus reduce the stress due to lexure.

The rod and fingers are made of different materials to reduce the likelihood of cutting and the spring pressure is suicient to carry the current and the area is suicient to provide low uni-t pressure.

In this embodiment of my invention, the rod 55 is a hollow tube as illustrated in Figure 4, and engages the contact 52 by means of the screw threads which have been cut into both at |93. Thus the contact 52 is fashioned from a cylindrical piece of metal of outer diameter equal to that of rod 55 and is turned down at |94to provide a means for a screw thread coupling between the Contact and rod 55.

For reasons which will hereinafter be set forth, the contacts 5| and 52 are hollowed at 202 and 293 respectively. In the novel design of the contacts, however, the hollow 263 assumes the form of a broached or forged hexagonal prism to provide` for engagement with a wrench of the type employed for the standard socket-head machine screws, and thus to permit the parts to be firmly secured together to provide for good electrical Contact and simple replacement.

Both contacts 5| and 52 are surfaced with a layer of arc resisting non-welding metal suitable for circuit breaker contacts. These metal faces 206 and 201 may be applied to the metal by brazing or soldering. Subsequent to the mounting of the arcing metal 206, 261, the contacts are the smooth chamfered surfaces 2|3, and 2|4, as illustrated in Figure 4, to: preclude interference between the edge of the Contact and its housing.

Contact 5| is not fixed to the frame lby the -circuit breaker air head or manifold 45, but is -the bearing 62 on the terminal 63.

The plurality of lingers 222 is illustrated in `Figure 4 and the cross-sectional View of the inlet head and contact housing, Figure 3. The individual fingers are spring pressed toward a central position by means of garter springs 223 and 224 which are positioned uponV the cylindrical .array of ngers'by thegrooves 225 and 226, turned in the cylindrical housing.

vhousing 2 I5 to provide clearance at 232.

These garter springs 223 and 224 function to assure positive mechanical and electrical contact between the lingers 222 and the outer surfaces of the contacts 5I and 52 during initial closing and final movement. The contact 5I is continuously biased by the compression spring GI and hence when contact 52 is in its open circuit position, the external flange 2|6 on contact 5I will engage the internal flange 2I1 on the contact housing along the surface 23|.

The circular flange 2|6 on contact 5| is of a diameter less than that of the inner wall of the Therefore, slidable surface contact between contact 5| and the housing 2|5 will only be present at the surface 221. The clearance at 232 permits sufcient finger movement to compensate for normal contact wear.

One end ofthe compression spring 6| is retained within the contact 5I by means of the cylindrical opening 233 which has been chamfered at 234 to preclude the possibility of the spring 6I binding with the edge of the opening 233.

A perforation 236 within the face of the head 45, which contacts the arcing chamber at |35 is provided to allow the passage of the contact 5I therethrough. The contact housing 2|5 is centrally supported within the head to assure alignment of the contact and the perforations.

The recess 24| is machined into the wall |24 of the inlet head 45 to secure a mating projection machined into the circular projection 242 on the contact housing 2 I 5.

The over-all length of the contact housing 2|5 is predetermined so that when secured against the flange 24| of the inlet head 45 sufcient clearance will be provided between the housing and the head to allow free movement of the fingers. Furthermore, the length of the cylindrical contact from the surface 23| of the iiange 2| 6 to the face 53 is made greater than the length of the projection 2|1 on the finger-like structure 222 in order for the face 53 of the Contact to project into the deionization chamber I3,

The contact housing 2|5 is flXedly mounted within the air blast inlet head 45 by the face plate 246 of the line terminal connector 241. This is best illustrated in the cross-sectional View, Figure 4. The line terminal 241 comprises a machined metal casting which serves to connect the bus bar II to the contact 5I through the contact housing 2|5. Thus the fiat plate 246 of the line terminal contains a projection 25| of a diameter equal to the inner diameter of the contact housing 2|5, which is inserted into the cylindrical opening of the contact housing to position the entire line terminal centrally with respect to the axis of the circuit breaker. .A plurality of machine screws 252 project through suitable perforations 253 within the plate 246 and engage a plurality of corresponding threaded perforations 254 contained within the air blast head or manifold 45.

Thus, the fastening of the bolts 252 will serve to secure the annular projection 242 on the housing 2|5 against the shoulder 24| on the inlet head 45 while also serving to assure a Xed relation between the line terminal 241 and both the contact 2|5 and the inlet head 45. The cylindrical projection 256 of the line terminal 241 serves a dual purpose in that it acts as a binding post to which the bus bar II may be secured and as a retainer for the compression spring 6|,

The periphery 262 of the cylindrical member 256 has been threaded to receive two suitable nuts 263 and 264. As illustrated in Figures 1 and 4 the bus bar I I is perforated at 21|, has been fastened to the projection 256 between the two nuts 263 and 264. Two different types of circuit connections are furnished to provide adjustment for the dimensions between the bus bars.

During circuit closures, the surfaces 53 and 5 of arc resistant material 236 and 251 engage as a result of axial displacement of contact carrying rod 55, and complete the circuit. When in the open circuit position illustrated in Figures l, 4 and 5, the distance between the face |53 of the latch and the corresponding face |52 of the slot in the plunger is greater than the corresponding distance between the faces 53 and 54 0f the contacts 5I and 52 respectively, and inasmuch as contacts 5I and 52 are of equal diameter, thv moving contact 52 will enter the contact nous ing 2|5 during the final closing movement.

The plurality of lingers 222 will then, under the iniluence of garter springs 223 and 224 grip the outer cylindrical surface of contact 52 and provide a low resistance path Ifor the current from the cylindrical surface of contact 52 to line terminal 241 in shunt with the arcing contact. At the end of the closing movement, the face 53 of contact 5I reaches a counterbore 2I8 in the contact housing which provides clearance therebetween and assures that the full pressure of the garter springs 233 and 224 are exerted in maintaining current carrying engagement between the plurality of iingers 222 and the contact 52.

Thus when the circuit breaker contacts are in full engagement, the contact resistance at the engaged surfaces 53 and 54 will be unimportant and the resistance that the separable contacts inject into the circuit will be determined solely by the contact resistance between the surface 221 and the outer surface of the contact 52. Therefore, irregularities which may appear upon the contact surfaces 53 and 54 due lto frequent arcing will not preclude positive low resistance vcontact when the circuit breaker is closed.

During the opening of the circuit breaker, contact 52 recedes from the contact housing 2|5 under the iniiuence of the opening springs and contact 5I resumes the position illustrated in Figures 4 and 5. The chamfered edge 2I3 of the arc resistant material 206 functions to facilitate the movement of contact 5| from the counterbore 2I8.

The above description of the various components which comprise the air inlets, contacts, and suitable supports therefor, have related to the specific embodiment of my invention illustrated by the accompanying figures.

However, it should be noted that the arcing chamber of the present inventionmay be utilized with many other types of air blast circuit breakers, and the foregoing description is primarily schematic and illustrative of but one type of system in which the novel arcing chamber may be incorporated.

The arcing chamber The arcing chamber i3 of my invention comprises a stack of metal plates insulated from each other and clamped together with both terminals and the air blast manifold, by means of the two insulating bolts I4! and |42. A perforation in each of the metal plates and a corresponding perforation in each of the insulating barriers provide, when assembled, a hollow cylindrical arcing chamber through which the contact 52 is moved by a plunger to engage the opposite contact and complete the electrical circuit.

Referring to the general external View, Figure l, the arcing chamber I3 comprises the composite metal plates 30| and the insulating barriers 302 and the entire laminated structure is clamped together by the bolts I4I, |42. Each of the composite plates 30| comprises two metal plates 303, 304 which are in surface contact at 305. The voltage in connection with which the circuit breaker is to be used determines the number of elements, thickness of barrier, and the provision of means for preventing surface leakage.

The cross-sectional views of Figures 4 and 5 illustrate the construction and mounting of the arcing chamber in somewhat greater detail. The laminated structure is terminated at one end by the inlet manifold 45 to permit the entry of air and at the other by the line terminal 63. Thus the contacts 5I and 52 are separated electrically by the sum of the dielectric properties of all of the insulating barriers 302. Obviously, therefore, the thickness of each individual barrier 302 and the number thereof are determind by the maximum voltage difference appearing between the contacts.

Contact 5| is shown in Figures 4 and 5 as proiecting slightly into the cylindrical arcing chamber and assumes this position when the contacts separate. During the interruption of the circuit, the contact 52 is carried from surface engagement with contact 5| to the position illustrated in Figures 4 and 5. Therefore, the arc which is the result of circuit interruption is drawn between the contacts 5I and 52 and wholly within the cylindrical opening 306 of the arcing chamber I3.

Contacts 5| and 52 have a central recess so that the arc will be drawn at the periphery thereof. In Figures 4 and 5, it should be noted that the perforation in the stack of metal plates is of a diameter only slightly greater than that of the contact 52 and that during the normal operation of contact 52 through the cylindrical chamber 30S, there is no metallic contact between the periphery of the contact and the plates comprising the arcing chamber I3.

Further, it should be noted that the air-gap when measured directly between the open contacts 5I and 52, as illustrated in these figures, is greater than the sum of the air-gaps measured lfrom the periphery of contact 5| through the stack of laminated plates and to the periphery of contact 52.

The actual arcing distance, if taken through the stack of plates as described, will be the sum of a series of short air gaps between the metal plates that are insulated from each other by means of the barriers 302.

Therefore, when contact 52 is withdrawn from surface engagement with contact 5I by means of its plunger 55, an arc will immediately be drawn between the outer edges of the two. The arc path will have an appreciable diameter and will be in proximity to the edges of the metal plates. The arc path will contact these metal plates, causing certain parts thereof to be short circuited by the metal.

Since the arcing distance when taken through the plates is relatively short, as described, there Will be a tendency for the arc to remain in contact therewith.

The transfer of the arc from the cylindrical arcing chamber 306 which is composed entirely of air to the series of short arcs formed between the metal plates adjacent the insulating barriers is thus greatly facilitated by both the annular construction of the contacts and the fact that the total length of the series of arcs formed between plates is less than the length of the arc which would be formed if drawn directly through the arcing chamber 306. Also as will herein- `after be described, the air ducts are arranged so that the outflowing air will tend to draw the arc into contact with the metal plates.

In the foregoing, I have indicated that the arc drawn between contacts will be transferred to the inner edges of a cylindrical opening which is formed by suitably perforating a stack of metal laminations and insulating barriers. The transfer of the arc to the metal stack results in proper deionization by means of both the cooling action of the metal plates, and an air blast which is conducted to the arcing chamber and discharged therefrom in the novel manner devised.

The arcing chamber provides means whereby the arc that is drawn between the contacts is broken into a series of short arcs between a stack of metal platesand is spun around the cylindrical opening provided therein, under the influence of a cooling and deionizing air blast. This is introduced to the cylindrical arcing chamber 306 in the form of an air vortex that spins each of the short arcs around the metal plates so that the arc terminals are in continuous movement. This action tends to prevent incandescent metal spots at the arc terminals which would introduce ionized gas into the arc stream, cools the plates and the arc path, and removes gas heated by the flow of current.

The sides of the exhaust passages comprise metal plates in electrical contact. Hence it is impossible for an arc to exist across the spaces and to be blown from the chamber. Ample cooling surface is provided to assure that the discharge is below the critical temperature of electrical breakdown.

Reference is now made to the cross-sectional views, Figures 4, 5, 6 and 7, and the broken perspective View of the metal plates and insulating barriers of Figure 8.

The laminated structure is built up of units comprising one each of plates 303 and 300 separated by insulating barriers 302, the exact number of units and barriers being determined by the capacity of the breaker and by the voltage and current ratings thereof.

As illustrated in Figure 8, the plate 304 comprises a web of metal 304a having integral guide vanes and channels on either side. The plan Views of the disk, Figures 6 and "I, show the nature of the guide vanes which have been cast upon the web 30411.

Referring to Figures 6 and 8, one face of the disc 304 has two similar, integrally molded channels 3I I-3I I of rectangular cross-section, formed between the walls 3 I 2 and 3I3, of the casting, and originating at the perforaticns 3|4, 3I4. These ducts are of diminishing cross-section and of spiral shape, as indicated in Figure 6.

The inner wall 3 I 3 of the channel has been cast as a continuous ribbon of metal spiralling around a central perforation 3M, and has been subsequently grooved-to provide a series of air nozzles 3I1 which discharge into the circular chamber 32| surrounding the perforation 3|4. Y

The disk 304 is provided with four circular protrusions, two of which, 322, 322 contain the perforations 3I4, 3I4 at the origin of the tapering spiral channels 3 I 3| I, to permit the introduction of an air blast. The other two ngerlike projections 323, 323 contain perforations 324, 324 to accommodate the insulating bolts |4| and |42 which function to clamp the stack of metal plates to the terminal and air blast manifold.

The exterior surface of the metal side walls 3 I2 and 325 are coplanar with the surface of the guide vanes which have been formed by machining the nozzle shaped openings 3|1. Thus, if a flat plate is placed across the surface of the disk 304 indicated in Figure 6, the integrally formed channels and guide vanes will provide air ducts of rectangular cross-section originating at the perforation 3I4 which spiral around a central perforation 3 I 4, and which tangentially enter into the circular chamber 32| around the perforation 3 I4 through a series of nozzle shaped openings 3|1.

Air flow within the channels 3|| is confined to the center of the structure of 304 by means of the metal wall 3|2 and 325. However, the air is permitted to enter the circular chamber 32| through the nozzles 3 I1.

The opposite face of the metal web 304a also contains integral guide vanes 330 and 33| to provide channels 332 of rectangular cross-section as indicated in Figure '7, emanating from the central perforation ,3|4. increase in cross section, and spiral toward the edge of plates 333 and 334.

It is important to note that Figures 6 and 7 are sectional view of the opposite sides of the disk 304 and that the perforation 3|4 illustrated in Figure 6 is exactly that which is similarly referred to in Figure '1. Correspondingly, the perforations 324, 324 which allow the passage of the bolts I4I and |42 and are identical in both gures, and thus the structure of the disk 304 may best be visualized by placing Figure 6 over Figure 7 so that the corresponding perforations are in alignment.

In the actual assembly of the deionization stack, the surface of the disk 304 which contains the nozzle shaped openings 3|1 and the spiral air ducts 3I| is juxtaposed against the barrier of insulating material 302, as indicated in Figure 6. The opposite surface of the disk 304, containing the integral guide vanes 330 and 33| is covered by the metallic plate 303 having a similar outline and having a perforation 331 which corresponds with the perforation 3|4 in the disk 304. Accordingly, the space between the plane surface 335 of the disk 303 and the surface 335 of the disk 304 comprises a series of spiral openings of increasing cross section emanating from the central openings 3 I 4 and 331.

As there are no enclosing metal ridges such as 3|2 and 325 on the surface of the disk' containing the guide vanes 33I, the spiral channels thus provide a passage between the inner circular openings 3|4 and 331 and the atmosphere. The metal disk 303 has the plane surface 325 in juxtaposition with that surface of the disk 304 illustrated in Figure '1.

The opposite surface 34| of the plate 303 is in contact with the insulating barrier 302. Figures 4, and 8 indicate that the disk 303 has been counter-bored at 340 to increase the leakage dis- These channels ,gradually tance between plates 303 and 304. Furthermore, the perforation 342 of the barrier is of a somewhat greater diameter than the corresponding coaxial perforations 331 and 3|4 in the disks`303 and 304 respectively, to allow an air path for the arc that is struck between the discs and across the barrier, and to avoid possible burning thereat.

The nozzles 3I1 may be machined to the full depth of the ribbon of metal 3I3 or they may be machined to any other depth consistent with the quantity of air required for effective operation as will hereinafter be described.

The axes of the nozzles 3|1 are oriented so that an air stream travelling down the channel 3|| will tangentially enter the circular chamber 32| to produce a high velocity air vortex within this chamber.

The disk 303 is preferably made of sheet brass counter bored at 340 and perforated at 321 as has already been described. The outline of the disk 303 corresponds to the outline of the plate 304, and as indicated in Figure 5, this plate has also been perforated at 345 and 345 to correspond with the perforations 3I4, 3I4 in the disk 303 and has similarly been perforated to accommodate the bolts |4| and |42.

When assembled as indicated in Figures l, 4 and 5, the stack comprises a series of pairs of plates 303 and 304 insulated from each other by the barriers 302. The perforations 3|4 and 326 in both the disks 304 and 303 are aligned as indicated and a suitable perforation 341 has been formed in the insulating barriers 302.

Therefore, when assembled, the arcing chamber |3 contains five hollow cylindrical passages. First the arcing chamber 305 is formed by the central perforations in the plates 303, 304 and the barriers 302, and permits the passage of the movable contact. Two diametrically opposite cylindrical chambers are formed by the perforations 3|4, 3I4 in the disk 304, the perforations 345 in the disk 303 and the perforations 301 in the insulating barrier 302, and these cylindrical chambers are in alignment with the divergent air ducts |25, |20 which conduct the air blast to the arcing chamber. Another pair of diametrically opposite cylindrical openings are formed by perforations within the barriers and disks 303, 304 and serve to accommodate the insulated bolts |4I, |42 which clamp the various plates together and to the inlet manifold 45 and the terminal 63.

The stack which comprises the arcing chamber I3 is terminated by a metal disk 35|, similar to casting 304 in that it contains the aforementioned air channels 3II and nozzles 3|1 as illustrated in Figures 6 and 8. The opposite surface 352 of the casting 35| is machined flat so that good surface contact can be made at |35 between this casting and the inlet manifold 45.

This plate 35| contains perforations 353 and 354 to correspond with the channels of the divergent inlet manifold and the cylindrical chambers III and II2 formed by corresponding perforations in the deionizing stack I3.

The opposite end of the stack is terminated by the terminal casting 63 which provides the necessary protrusions |45, I 40, |41 and |48 that seal the cylindrical air passages and provide supports for the nuts |53 and I 54 as hereinabove described.

Operation When the air blast is started by the actuation of the control valve I4, the pipe 44 and the inlet air blast head 45conduct air to the cylindrical chamber l I I and I I2 through the divergent channels |25 and |26 which are an integral .part 'of the manifold. The arrow |32 in Figure 5 indicate this air flow, and the iiow through the chambers I I I and I I2 are indicated by the arrow heads 355 in Figure 8.

ThisA air under pressure flows through the perforations in the barriers and the disks 303 and is thus conducted to the air channels 3|I inthe disks 304.

The air flow is extremely rapid due to the pressure under which it is delivered, and thus travels down channels 3I| and enters the chamber 32| which is formed between the web of metal 304a and the insulating barrier 302.

The nozzles 3I'l increase the velocity ofthe air as it flows into the chamber v32| and are di'- rected to cause a high velocity air vortex within the chamber. This air, indicated by the arrow heads 356, enters the cylindricalarcing chamber 306 formed by the central perforations in ithe plates and barriers.

.It has previously been pointed out that .the contact operating within the deionizing chamber will cause an arc to be drawn which will immediately be transferred to the edges of the Vcylindrical chamber 306. The contact 52 is illustrated schematically in Figure 8, and is being withdrawn in the direction of the arrow head 36|. Anarc has been drawn between contact 5I and .52, transferred to the edges of the plates forming the cylindrical arcing chamber and broken .into aseries of short arcs.

A characteristic arc 362 is shown across V.the metal plates 304 and 303 which have the insulating barrier 302 interposed therebetween. The current then flows from Vplate 303 rto its-contiguous plate 304. Another arc 363 between the metal plate 304 and the periphery of the contact 52 is also illustrated. As contact .52 continues to move in the direction indicated,- the `'arc 1363 will have its terminal transformed to the next metal plate 303.

The arcs are drawn along the edges of the cylindrical chamber 306 at a time when lthe air blast has been initiated by the electromagnetic device I5. And thus, the arcs are immersed Vin a high velocity air vortex. Therefore,v the .individual arcs will be spun around theedges ofthe metal plate at a velocity determined by the-pressure of the air blast, until deionization has been effected. The cool incoming air indicated by the arrow heads 355 will pass directly across the arc and the metal plates about which the arc'isspinning. Inasmuch as the metal plates have been made of brass or other metal, the heat conductivity of which is relatively high, they will assist the air stream in removing heat from the arc path. The air which enters the cylindrical chamber 306 is exhausted through the spiral channels 332 which are formed between the metal web 304a and the surface of the metal disk 303.

It is important to note that the metallic contact between the contiguous metal plates 303 and 304 will prevent the establishment of an arc between the edges of the perforations 331 and 3|4. There is no tendency, therefore, to blow the arc from the deionizing chamber through the exhaust channels, to endanger adjacent apparatus.

The air which is being discharged through the channels 332 is caused to traverse the flues 365 between adjacent insulating barriers 302. These flues-a-re formed by increasing the dimensions of the insulating barriers over those of themetal disks 303 and 304, so that .air exhausted from the plunger-like action of contact 52.

prises relativefrotation of the two,

spaces between these barriers has been cooled sufficiently to complete deionization.

The elevated temperatures obtained during circuit interruptions in ordinary circuit breakers ,cause incandescence at the are terminals which .in turn results in the Vaporization of the metals comprising the arcing contacts. This vaporization decreases the electrical resistance of the arc path and adds to the volume of incandescent gas which must be cooled or removed.

.In my novel arcing chamber, the high velocity air vortex therein maintains the arc in motion around the edges of perforations 331 and 3I4 and This the contacts and thus precludes the burning of the metal as in the case of a stationary arc.

The tangential velocity of the incoming air is effective in causing this continuous motion whereas the radial velocity of the incoming air is 'effective in removing heat from the arc itself and .assists in carrying away the ionized gases generated within the arcing chamber. All of these factors which are combined into my novel arcing chamber contribute to increase the interrupting capacity of a circuit breaker of given dimensions.

The speed of rotation of the arc, to protect the metal parts, need not be as great as that ernployed in some of the magnetic arc spinners `because the air blast removes heat from the surfaces of the plates and thus reduces the temperature rise.

An additional feature of my novel arcing chamber and its associated contacts is the As soon as the overload has occurred, and plunger 55 begins to travel toward the open circuit position indicated in'Figures 4 and 5, the air conducted through the .manifold 45 into the cylindrical ducts III and II.2,isoontrolled by the position thereof. That is, the plunger acts as a valve and restricts the flow .of air from all of the nozzles entering 'the chamber 306, except those in the vicinity of 'the arcsthat are being drawn between the contact and the metal plates.

A timing device may be provided with the cir- -cuit'breaker .to cut ofi the air blast after the arc has been extinguished. If necessary, the air blast may be allowed to operate when the contacts are being engaged to complete the circuit, if

there isany danger of sparking at the time of engagement.

As previously mentioned, the arcing chamber and its 'associated apparatus need not be limited to air as an arc quenching medium. `Thus by suitably designing the intake and discharge passages, oil or a similar huid may be employed.

As an additional feature for circuit breakers of high interrupting capacity wherein contact de terioration may be: aserious maintenance factor,

I ,provide a novel arrangement for securing a tact during successive operations thereof.

l-To provide for relative rotationbetween the Acontacts 5I and 52, I'rst mount the contact 5I so ll O that its motion is constrained to axial displacements relative to the frame of the breaker, that is, no rotation of this contact about its axis is permitted. This may be accomplished by keys or pins guided within slots 22| to prevent rotation. Contact 52, on the other hand, is mounted on plunger 40| which employs means whereby rotation about the aXis of the plunger is secured during circuit closures.

I provide a series of milled spiral slots 402 in that portion of the plunger 40| which engages the latch 11 of the release mechanism. As in the circuit breaker arrangement previously described, the releasing mechanism is operated by compressed air entering through pipe coupling 34 and coacting with piston 16 which is continuously biased upwardly by means of compression spring S3. The piston rod or latch 11 rides along the lower surface of the plunger 40| and in the embodiment illustrated in Figures 9 and l0, engages the spiral slots 402. The opening movement of the plunger 40| is limited by the stop 61 and associated cushion 65 by the annular shoulder 403.

When effecting circuit interruption, the influx of air through the pipe coupling 34 causes the latch 11 to be displaced against the action of spring 83 so that the upper portion 406 of the latch is well below the lower edge of the rod 40|. As previously mentioned, the rod 40 l, as rod 55 of Figure l, is spring biased towards the open circuit position and hence when the edge 406 of the latch 11 is withdrawn below the edge of the rod 40|, there will be a displacement towards the open circuit position. However, the springs which so bias the plunger 40| are arranged so that no rotation of the plunger 40| need occur during circuit interruption.

The release of the air from the cylindrical chamber 82 will again bring the edge 406 of the latch against the lower edge of the rod 40| and upon closing the circuit by displacing the plunger 40| in the direction of the Contact 5|, the edge 405 of the latch will drop into one of the spiral slots 402. As the latch 11 is maintained in rigid vertical relationship with respect to the circuit breaker frame by the bearing 92, further displacement of the plunger 40| will result in a rotation relative thereto. Correspondingly, rotation of plunger 40| will cause rotation of contact 52.

Upon the engagement of surfaces 53` and 54 of the contacts and 52, contact 5| will yield against spring 6|. However, this motion will vbe accompanied by relative rotation between the two and thus any particles or high spots which remain upon the surfaces due to previous arcing will be removed.

The termination of the displacement of the plunger 40| will bring the turned recess 401 into engagement with the leading edge 408 of the latch 11. The recess 446 has been turned to a depth greater than the depth of the individual slots 402, as is more clearly illustrated in Figure 10. At this point in the operation of the plunger 40|, the latch 11 will be forced into the recess 401 by the compression spring 83 and thus release of the manual or automatic operating lever will result in plunger 40| remaining in its closed circuit position.

The influx of compressed air through pipe coupling 34 will drive the piston 16 against the action of the spring 83 so that the edge 408 of the latch 11 will be somewhat below the surface of the rod 40|. Thus while the plunger rod 40| travels towards the open circuit position, there will be no slidable engagement between lthe latch 11 and the spiral slots 402. As a result, the plunger 40| will move towards the open circuit position without any relative rotation between the contact and the circuit breaker frame.

The next circuit breaker operation will repeat the aforementioned cycle. Hence the edge of the latch will fall into another slot during displacement of the plunger 40| in the direction of the contact 5| and again cause relative rotation therebetween. However, for this cycle, the plunger and contact will be rotated somewhat, relative to the position occupied on the preceding cycle because my novel plunger will only rotate during circuit closures.

The plurality of slots 402 indicated in Figure 9, when combined with the latch 11, is but one manner for obtaining relative rotation of the plunger 40|. In this embodiment, however, it is merely necessary to ascertain that the pitch of the individual spirals and the number of spirals provided, is sufficient to ensure that edge of the latch will fall into a spiral during circuit closure. The displacement of contact 5| required to complete the circuit will determine the relative rotation between contacts 402 and 405.

For the specic needs of the circuit breaker installation, these spirals 402 and distances may be adjusted as desired. The edge 406 of the latch may be an integrally curved portion of the latch 11 as shown or may be a small roller fastened thereto by means of a rivet or pin. However, it is important that the frictional contact between the edge and the individual spiral slots be reduced to a minimum.

There have here been described several modifications of circuit breaker which may be adapted to high capacity circuits and which eiect proper deionization in a very effective manner by means of a suitably directed blast of insulating, arcquenching fluid.

It should again be emphasized that apart from the arcing chamber i3, al1 the drawings associated therewith are schematic and that the novel arcing chamber and contact arrangement may be applied to any circuit breaker and that any of the well known tripping and manual operating mechanisms may be employed in connection therewith.

Thus, although there have here been illustrated but a few modications of the novel circuit breaker and arcing chamber, many others will become apparent to those skilled in the art. I prefer, therefore, .to be limited not by the specific disclosures hereinabove set forth, but only by the appended claims.

I claim:

l. In an arc extinguishing structure, contacts separable along a predetermined path, a plurality of insulating and metallic barriers substantially normal to the path of movement of contact separation, means including said barriers for conducting said fluid under pressure into the arcing space to cause a plurality oi arc quenching blasts substantially normal to said path of contact movement and between said barriers, the initiation of said plurality of blasts controlled progressively by said contact movement, said blasts causing rotary movement of an arc drawn between said contacts.

2. An arcing chamber for an air-blast circuit breaker; contacts operable in said arcing chamber; means for separating said contacts and drawing an arc therebetween; means including spaced.V arc extinguishing metallic plates for drawing and splitting said arc into a plurality of small arcs; means defined by said metallic plates for admitting air into said arcing chamber when said arc is drawn; said means for admitting said air causing said air to spin in planes substanrtially normal to the arc for spinning said arc about said plates.

3. In a circuit interrupter, an arcing chamber, said chamber comprising spaced metallic extinguishing plates having an axial bore, a movable Contact operable along the axis of said arcing chamber in said bore and engageable with a complementary contact therein, means for introducing a fiuid under pressure into said arcing chamber during the movement of said movable contact therein, and a path for exhausting said fluid from said chamber; means formed in said plates for guiding the incoming fluid under pressure in paths substantially tangential to the inner Walls of said arcing chamber and for causing said fluid to spin Within said arcing chamber around said plates in planes normal to said axis thereof.

4. In a circuit interrupter, a cylindrical arcing chamber, said chamber comprising metallic extinguishing plates spaced by insulation barriers and forming an axial bore, a movable contact operable along the axis of said arcing chamber in said bore and engageable with a complementary contact therein, means Yfor introducing a fluid under pressure into said arcing chamber during the movement of said movable contact therein, and a path for exhausting said iiuid lfrom said chamber, means for guiding the lncoming fluid under pressure in paths substantially tangential to the inner walls of said arcing chamber, said means comprising a plurality 4of nozzles communicating tangentially with the interior of said arcing chamber whereby the fluid under pressure is forced tangentially against the inner walls of said plates of the arcing chamber and spun therein.

5. In a circuit interrupter, a clamped laminated stack comprising alternate metallic layers and insulating barriers, said metal layers cornprising a first metal plate and a second metal plate, said second metal plate being in contact with said first metal plate on one surface and Vwith one of said insulating barriers on the other surface, central coaxial perforations in each of said `plates and barriers providing a hollow cylindrical chamber within said laminated stack, a first cylindrical contact yieldingly mounted and and projecting within said hollow central chamber, a second cylindrical contact operable Within said arcing chamber, means for governing the engagement and disengagement of said contacts, and means for conducting air to and exhausting air from said cylindrical arcing chamber, said means comprising integrally formed air ducts and nozzles in the individual laminations comprising the said stack.

6. In a circuit interrupter, an arcing chamber comprising a plurality of pairs of metal plates spaced by insulating sheets, all of the plates and sheets being secured in stacked surface to surface relation, each pair of metal plates consisting of a first metal plate having air intake guides in one surface thereof and air-exhaustA guides in the other surface; and a second flat metal plate which abuts one surface of said first plate andl contacts the guides on said surface for forming air ducts; one of said insulating sheets abutting the opposite surface and contacting the guides on said surface for forming air ducts on said side, a plurality of openings ineach of Vsaid plates and sheets adjacent the periphery thereof; said openings registering with each other and forming a `plurality of tubes; at least one of said tubes communicating with said air intake ducts; a central opening through each of the plates and sheets in said stack forming a hollow cylinder therein; and contacts operable in said hollow cylinder.

"7. In a circuit interrupter, an arcing chamber comprising a plurality of pairs of metal plates spaced by insulating sheets, all of the plates and sheets being secured in stacked surface to surface relation, each pair of metal plates consisting of a first metal plate having air-intake guides in one Vsurface thereof and air-exhaust guides in the other surface; and a second flat metal plate which abuts one surface of said first plate and contacts the guides on said surface for forming air ducts; one of said insulating sheets abutting the opposite surface and contacting the guides on said surface for forming air ducts on said side, a plurality of openings in each of said plates and sheets adjacent 'the periphery thereof; said openings registering with each other and forming a plurality of tubes; at least one of said tubes communicating with said airintake ducts; a central opening through each of the plates and sheets in said stack forming a hollow cylinder therein; and contacts operable in said hollow cylinder, said ducts communicating with said central cylinder, said air-intake guides termi.-

vnating in a plurality of nozzles directed substantially tangential to said central cylinder.

8. In a circuit interrupter, an arcing chamber comprising a plurality of pairs of metal plates spaced by insulating sheets, all of the plates and sheets being secured in stacked surface to surface relation, each pair of metal plates consisting of a first metal plate having air-intake guides in one surface thereof and air-exhaust guides in the other surface; and a second flat metal plate which abuts one surface of said first plate and contacts the guides on said surface for forming air ducts; one of said insulating sheets abutting the opposite surface and contacting the guides on saidfsurface for forming air ducts on said side, a plurality of openings in each of said plates and sheets adjacent the periphery thereof; said openings registering with each other and forming a plurality o'f tubes; at least one of said tubes communicating with said air intake ducts; a central opening through each of the plates and sheets in said stack forming a, hollow cylinder therein;

Vand contacts operable in said hollow cylinder, said ducts communicating with said central cylinder, said air-intake guides terminating in a plurality of nozzles directed substantially tangential to said central cylinder, one of said contactsl being supported upon a plunger and movable in said cylinder; said contact and plunger closing said air ducts when in said central cylinder and progressively opening said air ducts in moving out of said cylinder.

9. In a circuit interrupter, an arcing chamber comprising a plurality of pairs of metal plates spaced by insulating sheets, all of the plates and sheets being secured in stacked surface to surface relation, each pair of metal plates consisting of a first metal plate having air-intake guides in one surface thereof and air-exhaust guides in the other surface; and a second fiat metal plate which abuts one surface of said first plate and contacts the guides on said surface for forming air ducts; onel of saidinsulating sheets abutting the opposite Ysurfacev and contacting the guides on said surface for forming air ducts on said side, a plurality of openings ineach of said plates and sheets adjacent the periphery thereof; said openings registering with each other and forming a plurality of tubes; at least one of said tubes communicating with said lair intake ducts; a central opening through each of the plates and sheets in said stack forming a hollow cylinder therein; and contacts operable in said. hollow cylinder, said ducts communicating With said central cylinder, said air-intake guides terminating in a plurality of nozzles directed substantially tangential to said central cylinder, one of said contacts being supported upon a plunger and m-ovable in said cylinder; said contact and plunger closing said air ducts when in said central cylinder and progressively opening said air ducts in moving out of said cylinder, the central openings of each of said insulating sheets being larger in diameter than the co-rresponding openings in the metal plates, the said metal plates thereby projecting into said central cylinder, and forming a series of arc-quenching Yannular plates within the central cylindrical arcing chamber between which the arc is drawn.

10. In a circuit interrupter, an arcing chamber comprising a plurality of pairs of metal plates spaced by insulating sheets, all of the plates and sheets being secured in stacked surface to surface relation, each pair of metal plates consisting of a rst metal plate having air-intake guides in one surface thereof and air-exhaust guides in the other surface; and a second flat metal plate which abuts one surface of said rst plate and contacts the guides on said surface for forming 'air ducts; one of said insulating sheets abutting the opposite surface and contacting the guides on said surface for forming air ducts on said side, a plurality of openings in each of said plates and sheets adjacent the periphery thereof; said openings registering with each other and forming a plurality of tubes; at least one of said tubes communicating with said air intake ducts; a central opening through each of the plates and sheets in said stack forming a hollow cylinder therein; and contacts operable in said hollow cylinder; said ducts communicating with said central cylinder, said air-intake guides terminating in a plurality of nozzles directed substantially tangential to said central cylinder, one of said contacts being supported upon a plunger and movable in said cylinder; said contact and plunger cl-osing said air ducts when in said central cyl.. inder and progressively opening said air ducts in moving out of said cylinder, the central openings of each of said insulating sheets being larger in diameter than the corresponding openings in the metal plates, the said metal plates thereby projecting into said central cylinder, and forming a series of arc-quenching annular plates Within the central cylindrical arcing chamber` between which the arc is drawn, the said arc being spun in the chamber between the contacts and along the arc-quenching plates.' v

11. A metallic plate for an arc quencher, said plate having a central opening and at leastI one other opening; said openings extending from one facev to the opposed face of said plate; a plurality of guides on one surface of said plate defining channels leading from said other opening to said central opening, said channels following a spiral path and communicating with said central opening along line substantially tangential to said central opening.

12. A substantially rectangular metallic plate forl an arc quencher, said plate having a central opening and other openings at each of the corners thereof, a plurality of guides on one surface of said plate defining channels leading from two diagonally opposed corner openings to said central opening, and a plurality of guides on the other 4surface of said plate defining channels leading from said central opening to the periphery of the plate, said rst mentioned channels following a spiral path and communicating with said central opening along lines substantially tangential to said central opening, the other pair ofV diagonally opposed openings being adapted to receive and position securing means.

13. In a circuit interrupter, a first contact yieldingly mounted and engageable with a second similar contact non-rotatably supported upon a rotatable plunger, means for effecting the engagement and disengagement of said contacts by the linear movement of said plunger, and means operative solely during linear movement toward the fully engaged contact position for causing simultaneously the rotation transversely of the linear movement of said plunger and second contact.

14. In a circuit interrupter, a first cylindrical Contact yieldingly and non-rotatably mounted, and a second cylindrical contact engageable with said first contact and supported upon a rotatable plunger operable in a piston like manner along the axis of said contacts for effecting the engagement and disengagement thereof, said plunger being biased toward the disengaged position, a releasable latch engaging an annular shoulder on said plunger for maintaining said plunger in the engaged position, a plurality of spiralled slots uponl said plunger terminating at said shoulder, said latch being engageable with said slots solely lduring Contact engagement for causing relative rotation between the contact surfaces.

1.5. In a circuit interrupter, a cylindrical arcing chamber, a movable contact having an annular contact surface normal to the axis of the arcing chamber and engageable with a similar complementary contact therein, means for spinning the arc drawn between said contacts within the cylinder and about the annular contact surfaces, said means comprising means for introducing a fluid under pressure into said arcing chamber during the movement of said movable contact therein, and for guiding said fluid into paths tangential to the walls of said chamber for spinning said fluid and said arc, and a path for exhausting said iluid from said chamber, and means for breaking the arc into a plurality of serially connected arcs, said means comprising a plurality of spaced metallic annular projections eXtending to the cylindrical arcing chamber in planes normal to the axis of the chamber, said means for introducing said fluid into said arcing chamber being formed in said metallic projections.

16. In a circuit interrupter, an arcing chamber comprising a plurality of pairs of metal plates spaced by insulating sheets, all of the plates and .sheets being secured in stacked surface to surface relation, each pair of metal plates consist ing of a first metal plate having air-intake guides in one surface thereof and air-exhaust guides in the other surface; and a second flat metal plate which abuts one surface of said rst plate and contacts Athe guides on said surface for forming air ducts; one of said insulating sheets abutting the vopposite surface and contacting the guides on said surface for forming air ducts on said side,

a central opening through each of the plates and sheets in said stack forming a hollow cylinder therein; and contacts operable in said hollow cylinder.

17, In a circuit interrupter, an arcing chamber comprising a plurality of pairs of metal plates spaced by insulating sheets, all of the plates and sheets being secured in stacked surface to surface relation, each pair of metal plates consisting of a first metal plate having air-intake guides in one surface thereof, and air-exhaust guides in the other surface; and a second flat metal plate which abuts one surface of said first plate and contacts the guides on said surface for forming air ducts; one of said insulating sheets abutting the opposite surface and contacting the guides on said surface for forming air ducts on said side, a plurality of openings in each of said plates and sheets adjacent the periphery thereof; said openings registering with each other and forming a plurality of tubes; at least one of said tubes communicating with said air intake ducts; a central openingr through each of the plates and sheets in said stack forming a hollow cylinder therein; and contacts operable in said hollow cylinder, said air ducts communicating with said central cylinder.

18. In a circuit interrupter, an arcing chamber comprising a. plurality of pairs of metal plates spaced by insulating sheets, all of the plates and sheets being secured inv stacked surface to surface relation, each pair of metal plates consisting of a rst metal plate having air intake guides in one surface thereof and air-exhaust guides in the other surface; and a second flat metal plate which abuts one surface of said first plate and contacts the guides on said surface for forming air ducts; one of said insulating sheets abutting the opposite surface and contacting the guides on said surface for forming air ducts on said side, a plurality of openings in each of said plates and sheets adjacent the periphery thereof; said openings registering with each other and forming a plurality of tubes; at least one of said tubes communicating with said air intake ducts; a central opening through each of the plates and sheets in said stack forming a hollow cylinder therein; 'and contacts operable in said hollow cylinder, said ducts communicating with said central cylinder, said air intake guides terminating in a plurality of nozzles directed substantially tangential to said central cylinder, said air-exhaust guides directing the exhaust gases laterally through the stack to the outside thereof.

19. In a circuit interrupter, an arcing chamber comprising a plurality of pairs of metal plates spaced by insulating sheets, all of the plates and sheets being secured in stacked surface to surface relation, each pair of metal plates consisting of a first metal plate having air-intake guides in one surface thereof and air-exhaust guides in the other surface; and a second iiat metal plate which abuts one surface of said first plate and contacts the guides on said surface for forming air ducts; one of said insulating sheets abutting the opposite surface and contacting the guides on said surface for forming air ducts on said side, a plurality of openings in each of said plates and sheets adjacent the periphery thereof; said openings registering with each other and forming a plurality of tubes; at least one of said tubes communicating with said air intake ducts; a central opening through each of the plates and sheets in said stack forming a hollow cylinder therein; and contacts operable in said hollow cylinder, said. ducts communicating with said central cylinder, said air-intake guides terminatingin a plurality of nozzles directed substantially tangential to said central cylinder, one of said contacts being supported upon a plunger and movable in said cylinder; said contact and plunger closing said air ducts when in said central cylinder and-progressively opening said air ducts in moving out of said cylinder, the central openings of each of said insulating sheets being larger in diameter than the corresponding openings in the metal plates, the said metal plates thereby projecting into said central cylinder.

20. A metallic plate for an arc quencher, said plate having a central opening and at least one other opening; a plurality of guides on one surface of said plate defining channels leading from said other opening to said central opening; and a plurality'of guides on the other surface of said plate defining channels leading from said central opening to the periphery of the plate, said first mentioned channels following a spiral path and communicating with said central opening along lines substantially tangential to said central opening.

21. A substantially rectangular metallic plate for an arc quencher, said plate having a central opening and other openings at each of the corners thereof, a plurality of guides on one surface of said plate defining channels leading from two diagonally opposed corner openings to said centralr opening, and a plurality of guides on the other surface of said plate defining channels leading from said central opening to the periphery of the plate, said first mentioned channels following a spiral path and communicating with said central opening along lines substantially tangential to said central opening.

22. An arcing chamber for an air-blast circuit breaker; contacts operable in said arcing chamber; means for separating said contacts and drawing an arc therebetween; means for admitting air into said arcing chamber when said arc is drawn; said means for admitting said air causingr said air to spin in planes substantially normal't'o the arc for spinning said arc, a plurality of arc extingushing plates extending into and surrounding the arc, said air admitting means being formed in said plates; the said arc, when drawn, being subdivided between said plates and spun thereon.

23. In a circuit interrupter, a first cylindrical contact yieldingly and non-rotatably mounted, and a second cylindrical contact engageable with said first contact and supported upon a rotatable plunger operable in a piston like manner along the axis of said contacts for effecting the engagement and disengagement thereof, a releasable latch for maintaining said plunger in said engaged position, and a plurality of spiralled slots upon said plunger cooperable with said latch for causing the rotation of said plunger and second contact solely during contact engagement.

24. In a circuit interrupter, an arcing chamber comprising a plurality of pairs of metal plates spaced by insulating sheets, all of the plates and sheets being secured in stacked surface to surface relation, each pair of metal plates consisting

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