US2509015A - Circuit breaker - Google Patents

Description

May 23, 1950 w, PEAsE 2,509,015

CIRCUIT BREAKER Filed March 22. 1947 In ventor': Walter" L. Pease,.

b M His Attorngg.

i atented May 23, i950 UNITED CIRCUIT BREAKER Wa ter L. PeasdUp'per Darby, Pa., assignor to General Electric Company, a corporation of New York Application March 22, 1947, Serial No. 736,557

, 9 Claims. 1

My invention relates to circuit breakers and, more particularly, to those of the fluid blast type wherein a blade contact is operated with reciprocable movement out of and into conducting engagement with a, cooperating contact, the separa tion of such contacts taking place within the confines of an arc chute.

in one well-known form of fluid blast circuit breaker known as the cross-blast type, the opening movement is attended by a blast of pressure fiuid directed transversely across the are drawn between the separating contacts for the purpose oi extinguishing the arc to interrupt the circuit. The movable contact blade usually is operated for reciprocating movement in the chute by a grounded actuating mechanism through a suitable insulated connection.

In such circuit breakers, particularly when the blademust be made of a large cross-sectional area for the continuous carrying of high amperage currents, an undesirable piston effect is produced on the blade in consequence of the blast pressure within the chute which tends to eject the blade from the arc chute with excessive speed and force so that the opening movement becomes difficult to control. For this reason it is advantageous to keep the mass and especially the effective piston area of a reciprocating blade contact to minimum values, and my invention is directed particularly to achieving these desirable characteristics. A

Accordingly, it is an object of my invention to provide an improved high current carrying crossblast circuit breaker. V 7

Another object of my invention is to provide an improved cross-blast circuit breaker, the movable contact blade of which is capable of carrying high current continuously and is productive of but comparatively small piston efiect during the opening movement thereof.

Further objects and. advantages of my invention will become apparent a the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For better understanding of my invention, reference may be had to the accompanying drawings in which Fig. 1' is a cross-sectional elevational view of the contact structure in an arc chute which one form of my invention might assume; Fig. 2 is a cross-sectional view of Fig. 1 looking down upon the intersecting plane E -E showing particularly the cross-sectional configuration of the contact blade illustrated in Fig. 1;

Fig. 3 shows a different cross-sectional configuration of another contact blade falling within the scope of my invention; Fig. 4 shows yet another contact blade cross-section, this variant being of cylindrical form and being an enlarged cross-section on the line 4-4 of Fig. 5; while Fig. 5 shows a cross-sectional elevational View of the interrupting structure of a, circuit breaker embodying the cylindrical blade whose cross-section is illustrated by Fig. 4.

For the purpose of illustrating my invention, a cross-blast interrupter similar to that disclosed in the U. S. Patent 2,284,842 issued June 2, 1942, and assigned to the same assignee as the present invention, has been partially shown in Fig. 1; while a cross-blast interrupter possessing some structural features disclosed in the joint application, Serial Number 586,892 of William E. Paul et al., now Patent No, 2,452,953, issued Nov. 2, 1948, also assigned to the same assignee as the present invention, has been shown in Fig. 5. In both of these illustrations an arc chute generally indicated by l is shown mounted upon a supporting base insulator 2 within which chute is disposed fixed contact structure 3 which includes a suitable plurality of short resilient current carrying fingers 4 and a lesser number of longer resilient arcing fingers 5. A movable blade structure, generally indicatedby 6, cooperates with the fixed contact fingers 4 and 5 and is operated with a vertically reciprocal motion out of and into conducting engagement therewith for interrupting and. completing the circuit respectively through the agency of an appropriate operating mechanism (not shown). Such an operating mechanism, which might be of the pneumatic type disclosed in the joint Patent 2,436,190 of Alexander C. Boisseau, et al., granted February 17, 1948, which is assigned to the same assignee as the present invention, ma be connected to the blade in any suitable manner, such as by an insulated operating rod 1 as shown in Fig. 1 or by insulated links 8 as shown in Fig. 5.

At this stage it may be observed that, in accordance with my invention, the blade 3 of Fig. 1 is of a generally U-sectioned configuration, as clearly illustrated by the sectional view of Fig. 2; while in Fig. 5, I have shown another expedient configuration such as a hollow cylindrical form which is clearly illustrated by the sectional view of Fig. 4. However, whatever its form, those skilled in the art will understand that the movable blade 6 is preferably guided for rectilinear reciprocal motion by means such as, for example, rollers 9 of Fig. 5; and that the circuit through the breaker will follow the current path via arrow l0, fixed contact 3, contact fingers 4 and 5, blade 6, through a set of sliding contact which bears conductively against the blade b and which con tacts are indicated by the numeral 5 l and thence out of the breaker through a bushing stud or other suitable conductor represented by the arrow I2. Also well understood in the art is that, coincidental with the initiation of the opening movement of the blade 8. a blast of pressure fluid is released by well-known means from a source (not shown) through the blast conduit it and which blast is directed into the power arc drawn between the fixed arcing fingers 5 and the cooperating tip Id of the upwardly moving blade ii, so that the are thus drawn is blasted to extinction harmlessly within the safe confines of the arc chute l thereby interrupting the circuit. The gaseous products of the said arcing are exhausted to atmosphere, after passing through cooling devices I5, through a suitable disposal duct such as l6 shown in Fig. 5.

In prior cross-blast breakers of high current capacities, say on the order of 5005) amperes, economy of conducting material has been achieved by employing a hollow blade conductor so as to take advantage of the well-known skin effect. Such a hollow rectangular reciprocating blade as shown, for example, in Fig. l of U. S. Patent 2,298,773, assigned to the same assignee as the present invention, would be very satisfactory if the efiicient carrying of current and the effective interruption of the circuit were the only advantageous factors to be considered. However, such a hollow blade is attended by the disadvantage that the blast pressure introduced into the arc chute exerts a piston effect upon the whole cross-sectional area of the blade, including the non-current-carrying core; for hitherto such hollow blades have been provided with means for sealing elf the hollow core to atmosphere in order that all of the extinguishing blast may be gainfully directed transversely across the path of the separating contacts for interrupting the circuit.

In accordance wtih my invention, instead of having the hollow blade carry its own core sealing means so that upon it also is imposed the cores piston load, I eifect the improvement whereby the sealing means for the hollow blade is supported independently of the blade so that the piston force of the extinguishing blast thereon is borne by some other part of the interrupter or breaker structure where this pressure will produce no disadvantageous eifect. Referring now to Fig. 5, in which I have represented the blade 6 as a hollow conducting tube, it will be observed that the hollow core of the blade is closed to atmosphere by the barrier or piston member ll. Although in certain cases it is conceivable that, if a barrier such as ll were arranged for movement relative to the arc chute as well as to the hollow blade, certain attributes might ensue; I prefer simply to support the barrier ll immovably with respect to the arc chute or circuit breaker structure. Accordingly, in this embodiment of my invention, the blast pressure against the inner face of the fixed barrier ll is opposed by the support ing strut or rod is which in turn is secured by a suitable mounting device it to the stationary exhaust duct [5. Obviously then, the piston effect of the fluid blast tending to thrust the blade toward open position is limited solely to that exerted upon the annular cross-sectional area of the circular wall of the blade itself, for the pressure upon the hollow core portion is transmitted through the rod l8 to the exhaust duct l5 which is entirely independent from the blade 6.

Fig. 3 illustrates another embodiment that my invention might assume and shows a different hollow blade 26, in this instance the blade being of a generally rectangular cross-sectional configuration. It is very similar to the cross configuration of the hollow rectangular blade of the aforesaid Thumin patent excepting that in the present instance the rectangular wall of the blade is broken so as to provide a longitudinal gap or slot 2! extending along one side of the blade length. it will be obvious that if the gap 2.! were not provided, an externally sup-ported square stationary barrier or piston could be disposed in the hollow core for minimizing the blade piston effect which would function as the full equivalent of the above described circular barrier or piston ll of Fig. 5. As an alternative, however, by providing the gap ii I can support therethrough by a neck portion 22, a suitable rectangular barrier member 23 thereby connecting it directly to the adjacent arc chute structure.

Or again, I may choose to widen the gap 2! so as to eliminate the narrow neck portion 22 entirely, in which case the hollow blade crosssection would then conform to the U-shaped configuration depicted in Fig. 2, from which illustration it is clearly evident that the barrier portion A l proceeds directly from the arc chute end structure without any constriction in its width such as that which produces the narrow neck portion 22 in Fig. 3.

From the side elevational views of Figs. 1 and 5, it will be observed that the fluid pressure resisting barrier members such as 24, 23, or IT, all of which members conform closely to the contour of the hollow section of their respective blades 6, are preferably disposed substantially within the compass of the arc chute structure. Therefore, at the end of the opening stroke, the blade may be drawn clear of the arc chute with a safe air break or gap existing between the blade tip and the chute structure thereby minimizing voltage breakdown across the separated contacts in the breaker-open position. The lower face of the barrier members 24, 23, or I! may be located in any desired position. For example, in Fig. 1 I have chosen to locate the lower surface of 24 generally abreast of the blast conduit l3 and obviously such surface may be shaped or streamlined in any suitable manner for favorably influencing the adjacent blast proceeding from the conduit l3.

I have found, for reasons given below, that the U-sectioned configuration of the hollow blade 6 depicted in Figs. 1 and 2 provides a very convenient and practical substitute for a completely circular hollow blade which, as those skilled in the art will appreciate, represents that hollow configuration that will carry the greatest current with minimum cross-section and hence, theoretically, can be made to operate with the least piston effect. Firstly, the U blade is capable of satisfactorily carrying high current density suitable for upper ratings due to its constituting a walled hollow section whereby substantial advantage is taken of the aforementioned skin effect. Secondly, the barrier means '24 for sealing off the hollow portion of the U blade is readily constructed as a component part of the arc chute structure as is clearly apparent from the drawing. Thirdly, the U blade may conveniently be fabricated from a pair of similar or identical flat bar-like blades 25, the said pair of blades preferably being. interconnected rigidly together by a third walled member 26 to the biases are secured by suitable means such as rivets or studs 21'. In the embodiment. shown, member 2% is constructed as a T-s'ecti'oii so that. the extreme downstream point of the arcing tip [4, onto which the blast drives one root of. the power are, may lie under the rib of the 11, In this position, the intensely hot arc is beyond the immediate region of the blade current-carrying walls where it is not likely to damage the current conducting surfaces thereon. Furthermore, it Will be a preci'ated that the intermediate. member 26 serves as a mechanical reinforcement between the two spaces" blades. 25 which prevents possible damage from distortion or these blades when subject to high magnetic stressesv under heavy short; circuit conditions,v for such stresses tend to cause the blades to move forcefully toward each other.

From the foregoin detailed explanation and discussion, it will be apparent that I have provided new and useful interrupting devices for cross fluid blast circuit breakers capable of carrying high currents and yet whose current carrying blades are not subject to undue piston effect from the blast released into the arc chute. When it is considered that three similar single pole interrupter units, such as have been described indetail above, are usually controlled by a common operating mechanism so. as to constitute a unit triple pole circuit breaker; it will be appreciated that my invention can produce a substantial total reduction in undesirable blade piston effect in a given circuit breaker. Accordingly, similar or identical operating mechanisms may be used for these high current carrying circuit breakers as are used for the lesser amperage breakers of the same product line or series. It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

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

1. An electric circuit breaker of the fluid blast type comprising relatively movable contacts separable to draw an arc therebetween, arc chute structure for confining said are therein, means for directing a blast of arc extinguishing pressure gas transversely across the path of separation of said contacts in said are chute for interrupting the circuit, one of said contacts constituting a walled hollow-sectioned blade longitudinally reciprocable in said are chute structure, and barrier means disposed substantially within the compass of said hollow-sectioned blade and conforming closely to the contour of the hollow section of said blade so as efiectively to isolate one end of the hollow section of said blade from the fluid blast, said barrier means being supported independently of said blade whereby the piston effect of said blast on said blade is limited to the cross-sectional area of the walls of said blade.

2. An electric circuit breaker of the fluid blast type comprising relatively movable contacts separable to draw an arc therebetween, arc chute structure for confining said are therein, means for directing a blast of arc extinguishing pressure gas transversely across the path of separation of said contacts in said are chute for interrupting the circuit, one of said contacts constituting a Walled hollow-sectioned blade longitudinally reciprocable in said. are chute structure, barrier means disposed within and conforming closely to the contour of the hollow section of said made so as effectively to isolate oneend of the hollow section of said blade from the fluid blast, and means for supporting said barrier means independently of said blade whereby the piston effect of said blast on said blade is limited to the crosssectional" area of the walls ofv said blade.

3. An electric circuit breaker of the blast type comprising relatively movable contacts separable to draw an arc therebetween,- arc chute structure for confining said are therein, means for directing. a blast of arcextinguishing pressure gas transversely across the path of separation of said contacts insaid arc chutefor interrupting the circuit, one of said contacts constituting a walled hollow-sectioned blade longitudinally reciprocable in said are chute structure, barrier means disposed within and conforming closely to the contour of the hollow sectiorlof said blade so as effectively to isolate one end of the hollow sectionof saidblade from the fluid blast, and l .eans for transmitting the force impressed upon said barrier means by said blast to an associated member of said breaker other than said blade whereby the piston effect of said blast on said blade is limited. to the cross-sectional area of the walls of said blade.

l. An electric circuit breaker of the fluid blast type comprising relatively movable contacts separable to draw an arc therebetween, are chute structure for confining said are therein, means for directing a blast of arc extinguishing pressure gas transversely across the path of separation of said contacts in said are chute for interrupting the circuit, one of said contacts constituting a walled hollow-sectioned blade longitudinally reciprocable in said are chute structure,

' barrier means disposed within and conforming closely to the contour of the hollow section of said blade so as effectively to isolate one end of the hollow section of said blade from the fluid blast, an opening in a sidewall of said hollow blade, and means for supporting said barrier means from said are chute structure through said opening whereby the piston effect of said blast on said blade is limited to the cross-sectional area of the walls of said blade.

5. An electric circuit breaker of the fluid blast type comprising relatively movable contacts separable to draw an arc therebetween, arc chute structure for confining said are therein, means for directing a blast of arc extinguishing pressure gas transversely across the path of separation of said contacts in said arc chute for interrupting the circuit, one of said contacts constituting a walled hollow-sectioned blade longitudinally reciprocable in said are chute structure, the wall structure of said blade defining a generally U- sectioned portion, and said are chute structure having a corresponding U-shaped aperture for receiving said blade slidingly therein.

6. An electric circuit breaker of the fluid blast type comprising relatively movable contacts separable to draw an arc therebetween, arc chute structure for confining said are therein, means for directing a blast of arc extinguishing pressure gas transversely across the path of separation of said contacts in said arc chute for interrupting the circuit, one of said contacts constituting a walled hollow-sectioned blade longitudinally reciprocable in said are chute structure, the wall structure of said blade defining a generally U-sectioned portion and comprising a pair of similar spaced flat bars rigidly interconnected by an intermediate bar which constitutes the bight of the U, and said are chute structure having a corresponding U-shaped aperture for receiving said blade slidingly therein.

7. An electric circuit breaker of the fluid blast type comprising relatively movable contacts separable to draw an arc therebetween, arc confining structure for drawing said arc therein, means for directing a blast of arc extinguishing pressure gas into the path of separation of said contacts in said are confining structure for interrupting the circuit, one of said contacts constituting a hollow cylindrical blade longitudinally reciprocable in said are confining structure, a barrier disposed within the hollow core of said blade for substantially preventing the escape of pressure fluid from said arc-confining structure through said hollow blade, and means for supporting said barrier independently of said blade whereby the piston effect of said blast on said blade is limited to the cross-sectional area of the circular wall of said blade.

8. An electric circuit breaker of the fluid blast type comprising relatively movable contacts separable to draw an arc therebetween, structure for confining the arc therein, means for directing a blast of arc extinguishing pressure gas into the path of separation of said contacts in said structure for interrupting the circuit, one of said contacts constituting a tubular blade longitudinally reciprocable in said are confining structure, and a barrier disposed substantially within and conforming closely to the contour of the hollow core of said blade for effectively isolating one end of the hollow core of said blade from the fluid blast, said blade being movable independently of said barrier.

9. An electric circuit breaker of the fiuid blast type comprising relatively movable contacts separable to draw an arc therebetween, structure for confining the arc therein, means for directing a blast of arc extinguishing pressure gas into the path of separation of said contacts in said structure for interrupting the circuit, one of said contacts constituting a tubular blade longitudinally reciprocable in said are confining structure, and a fixed barrier arranged in the hollow core of said tubular blade and conforming closely to the contour of the hollow core of said blade for effectively isolating one end of the hollow core of said blade from the fiuid blast.

WALTER L. PEASE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,365,132 Amer et a1 Dec. 12, 1944 2,382,850 Bennett Aug. 14, 1945

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