US2507971A - Circuit breaker - Google Patents

Description

May 16, 1950 A. GUILLAUME ET AL. 2,507,971

CIRCUIT BREAKER Filed June 10, 1946 Patented May 16, 1950 CIRCUIT BREAKER Andr Guillaume and Albert Thibaudat, Seine,

France, assignors to Forges et Ateliers de Constructions Electriques de Jeumont, Paris,

France Application June 10, 1946, Serial No. 675,554 In France June 25, 1945 12 Claims.

The operating conditions of modern electrical networks impose upon circuit breakers, and particularly upon circuit breakers of the quick reclosing type, constantly increasing requirements with res-peet to breaking capacity and speed. Moreover, in some high power circuit breakers, it is dangerous to effect a very rapid reclosing of the circuit followed by a new circuit break, in view of the fact that such break runs the risk of being produced in an insufficiently regenerated medium. This drawback is particularly pronounced, for instance, in certain apparatus with a rectilinear movement of the contact rod which is displaced in one and the same confined space. This at times makes it necessary to provide for the re-closing of separate parts which complicates the arrangement of the apparatus and increases their bulk and the price.

This invention, which applies to circuit breakers comprising two or more cut-outs in series, relates to means making it possible to bring about an appreciable increase in the circuit breaking speed and capacity, as well as to avoid the drawback pointed out above.

In accordance with the present invention these favorable results can be obtained by improved means such as suitable guidance of the arcs resulting from a properly directed iluid ilow, proper selection of the speed of the movable contacts, and by the application of resilient means for suitably delaying and prolonging the arc extinguishing action.

When a powerful circuit breaker interrupts a very high overload, the electrodynamic forces and the whirling movements of the quenching fluids are capable of elongating the arcs while giving them an irregular shape. This uselessly increases the thermic effects, imposes excessive forces on the circuit breaker and creates very substantial counter pressures which affect the circulation of the arc extinguishing iiuids. Moreover, by moving away from the trajectories of the movable contacts, the arcs may more or less completely escape the blow-out action of these iluids, of which they ionize and heat parts which normally should remain fresh in order to be available for a subsequent re-closing cycle.

In accordance with one aspect of this invention, all kthese drawbacks are avoided with the aid of suitable guiding parts arranged in the vicinity of the normal trajectory of the arcs subject ed to the action of the quenching fluid, these parts being operated in such a way as to keep said arcs on the trajectory of the movable contacts by the action of the arc extinguishing fluid directed under the optimal conditions.

On the accompanying sheet of drawing,

Fig. 1 is a somewhat diagrammatic vertical section taken along line B-D of Fig. 2, through an illustrative embodiment of the invention, as applied to a rotating circuit breaker with a plurality vof make-and-break points in a quenching fluid such as oil, and

Fig. 2 is a horizontal section along of Fig. 1.

On the said figures of drawing, the movable equipment is made up of a rotatable insulating shaft I carrying an inclined rod 2 of conductive material, the said rod extending through a bore in shaft I, as shown. Except for the ends thereof, the exposed portions of rod 2 are sheathed in insulating material 2a. The free ends cooperate severally with the double-sided xed contacts 3 and 4. These contacts are of the same double-U type, the several U-shaped sockets, which snugly receive the aforesaid free ends of rod 2, being arranged to open in opposite directions as shown. The contacts 3 and 4 are severally connected with lead wires 5 and 6. The parts are housed in cylindrical insulating receptacle 'I which is filled with oil or other suitable quenching iiuid up to level 8. The inset ends Ia and 'Ib of receptacle 'I are also of insulating material.

The parts can be arranged so that the lower arc, formed between the contacts 2 and 4, is started a little sooner than the upper arc, formed between the contacts 2 and 3, so that the upline E-F per arc is at a suitable moment subjected to the extinguishing action engendered by the lower arc.

The upper end of contact rod 2 moves in the annular channel 9, Fig. 1, provided in a diskshaped part I2 of insulating material mounted interiorly of end Ia and in juxtaposition thereto. A similar annular channel can be provided in the lower part of the receptacle 'I on the upper face of the inset 1b. Communication between the oil well formed above end 'Ia and the interior of receptacle 'I is realized through the medium of aligned bores I0 and I3 provided respectively in parts I2 and 1a. An arc extinguishing exhaust flow of oil is thus directed to push the upper arc towards the bottom of the channel 9, notwithstanding the shown open form and the relative shallowness of the latter. By suitably configuring channel 9-as for instance arranging the inner wall thereof obliquely as illustratedand by disposing openings I0 and I3 at the points where the arc rupture always occurs, the oil is directed under the most favorable conditions and maximum arc extinguishing effect is realized.

It will be clear that, regardless of the type of circuit breaker, the are is thus effectively kept on the trajectory of its movable electrode, which makes it possible to impart an optimal length thereto. The successive breaks, which are connected in series, can be staggered in such manner as to cause the blow out action to take place at the most favorable instants. Finally, in order that the breaks may be most enicacious from the standpoint of time, the speed of the movable contacts may be suitably selected and varied as a function of the shape and construction of the guiding parts.

It has been found that by the combined expedients of staggering the points of disconnection, the guiding of the arcs, the directed quenching end the suitable speed of the movable contacts, a very appreciable increase in the power and speed of interruption is realized. Furthermore, owing to the immobillty of the quenched arcs and to the directed fluid flow, the hot and ionized residue left by the blown arcs is Very quickly removed without its being able to ad-mix with the surrounding fluid. This accelerated regeneration of the dielectric strength constitutes an important advantage, particularly as regards the rapid re-closing of the circuit breakers.

In the illustrated embodiment, this advantage is of especial significance. In the course of its first circuit interruption, the upper end of the contact rod 2 describes the arc of circle AB shown in Fig. 2; in the course of the :re-closure it describes the arc BC and during the second circuit interruption the arc CB. Each of the angles AB and BC can be practically equal to 180.

It ls therefore seen that the successive cycles of the reclosing operation utilize different semicircles of the guiding channel 9, and in view of the fact that each time the residue from the arc is prevented from contaminating the oil of the other half of the trajectory, the re-closing and the entire second cycle are always effected in a fresh environment, that is to say under very good conditions. Thus the appreciable result is that in the course of the second break the disconnecting power of the circuit breaker is the same as in the course of the first, which represents an important advantage as against certain `apparatus wherein the second interruption does not have the same power.

The operation described can be improved by providing on the shaft l a rotating obturator I!! which, of the openings l and I3, only unmasks those which are in the vicinity of the arc.

It goes without saying that the means of this invention and their variations can be applied not only to rotating oil jet circuit breakers which have just been mentioned by way of example, but to other circuit breakers having two or more breaking points in series and comprising a liquid or gaseous quenching.

When the arc extinguishing fluid is a liquid, it may be ladvantageous to attenuate the hydraulic excess pressure and more particularly to prolong its action by the application of suitable elastic parts adapted to modify the moment of initiation as well as the intensity and duration of the arc extinguishing fluid ow. This makes it possible to have greater freedom in the choice of the speed of the contacts, of the displacements among the series breaks, of the shape and section of the guiding channels, of their circulation openings, etc.

In the particular case of the device described above it is possible to use with that end in View for instance a toroidal body Il, Fig. 1, made of elastic material such as rubber and lled with air, as well as any other elastic means capable of producing the above effects. These devices can be placed in the suitable parts of the circuit breakers, for instance near the first partial arc.

We claim:

l. In a circuit breaker of the fluid blast type having a housing with two end walls, arc-blowing exhaust openings in the upper end wall and a plurality of fixed and movable contacts producing at least two arcs in series, means guiding the exhaust llow of said fluid from said housing through said openings comprising a relatively shallow groove-like channel in the underside of the upper end wall, opening towards the interior of said housing, said channel partially surrounding the path of a movable contact and said exhaust openings being located in said channel whereby an arc formed may be maintained freely in Said channel by the action of the fluid blast in lixed position along the path of said movable contact and in front of said arc-blowing exhaust openings.

2. In a circuit breaker of the fluid blast type according to claim I, wherein a pressure responsive elastic means positioned within the said housing is provided to cooperate with said guiding means for delaying and lengthening the action of the guided fluid blast.

3. A circuit breaker of the character described: comprising a housing with two end walls containing an arc-extinguishing fluid and having a plurality of arc-blowing exhaust openings in the upper end wall for carrying a flow of said fluid, a pair of spaced fixed terminal contacts, a movable contact element engageable after a practically complete rotation with said fixed contacts, whereby the medium in which the circuit interruption and incident arc formation take place is always different from the medium in which the preceeding and succeeding circuit interruptions and arc formations take place, 4and means for guiding the exhaust flow from said housing towards said openings to maintain by said exhaust flow a non-confined arc along the path of its movable contact in front of said openings, said flow guiding means being formed by a relatively shallow groove-like circular channel located in the underside of the upper end wall7 opening towards the interior of said housing and partially surrounding the path of an end of said movable contact element, and said exhaust openings being located in said channel.

4. A circuit breaker of the character described; comprising a housing with two end walls containing an insulating arc-extinguishing fluid and having in the upper end wall a plurality of exhaust arc-blowing openings for said fluid, a pair of spaced fixed terminal contacts, a movable contact element engageable with said fixed contacts, means guiding the flow of said fluid from said housing to said blowing openings for producing an efficient arc extinction in said openings, said last named means comprising a relatively shallow groove-like channel located in the underside of the upper end wall, opening towards the interior of said housing and having at its bottom said exhaust openings whereby an arc formed is immobilized by the action of the fluid flow along the path of the movable contact in front of said openings so that said arc is efficiently extinguished although non-coniined.

5. A circuit breaker of the character described, comprising a housing with two end walls containing a dielectric arc extinguishing fluid and having a plurality of arc blowing exhaust openings to discharge said uid, a pair of spaced iixed terminal contacts, a movable contact element mounted to effect a full rotation and to cooperate with said fixed contacts whereby the space in which the arc is formed during an interruption is always different from the space in which the succeeding arc is formed, elastic pressure responsive elements positioned within the said housing to increase the duration of said arc blowing discharge flow and means for directing said discharge flow from said housing through said arc blowing openings and for maintaining freely lan arc formed in the path of its movable contact in front of said openings by the action of said directed flow, said last named means comprising an open and relatively shallow groove like channel in the underside of the upper end wall, partially surrounding the path of an end of the movable contact element and opening towards the interior of said housing, whereby the arcs although non-restrained are immobilized in optimum position.

6. A circuit breaker of the character described; comprising a housing with two end walls containing a dielectric fluid and having a plurality of are blowing iiuid exhaust openings, a pair of spaced xed terminal contacts, a movable contact element rotating at a predetermined rate of speed and effecting a full rotation to engage with said iixed contacts whereby the space and the medium in which an arc is formed is always diiTerent from the space and the medium in which a succeeding arc is formed, and guiding means for directing said i'luid from said housing to said iarc blowing exhaust openings to maintain freely an arc in optimum position in the path of the movable contact in front of said openings by the action of the uid flow to produce an eilicient arc extinction, said last named means comprising an inwardly open relatively shallow kcircular channel iri the underside of the upper end wall, having the form of a recess with obliquely disposed walls partially surrounding the path of said movable contact mem-ber `and said openings being located at the bottom of said recess.

, 7. A circuit breaker of the character described; comprising a substantially cylindrical housing having two end walls, the upper end wall being inset to provide a well thereabove, said housing and said well containing ia dielectric fluid, resilient pressure responsive means, said upper end wall having a plurality of arc blowing exhaust openings therein providing communication between said housing and well, a pair of spaced iixed double sided contacts mounted on said end walls, and a rotatable contact member having ends engageable successively with both sides of said iixed contacts, said upper wall having at its interior surface an inwardly open relatively shallow annular iluid guiding recess havingsaid exhaust openings located at the bottom thereof, the upper fixed contact oi' said fixed contacts being disposed in said recess and the path of movement of the upper end of said rotatable contact member being located in said recess, said fluid guiding recess maintaining freely the upper arc formed by dynamic action of the exhaust flow in the path of said rotatable contact in iront of said exhaust openings, said dynamic action being lengthened by the action of said resilient pressure responsive means, positioned inside said housing.

8. A circuit breaker according to claim '1, wherein the inner walls of said recess are obliquely disposed to guide the arc extinguishing iiuid in optimal manner from the housing to the exhaust openings in order to immobilize the upper arc in optimum position with respect to the fluid flow.

9. A circuit breaker according to claim 7, wherein the inner walls of said recess are obliquely arranged to direct the dielectric fluid in optimal manner for fixing freely the upper arc in non-confined position whereby the lprolonged blow-out action is most eiiicient, and a rotatable shaft extending through said housing and having said movable contact member airlxed thereto.

10. In a circuit breaker, an interrupting unit comprising an insulating housing with two end walls containing dielectric arc extinguishing fluid and having a, plurality of are extinguishing fluid discharge openings in the upper end wall thereof, two fixed contacts, a rotatable contact member engageable with saidrlxed contacts, fluid guiding means comprising in the underside of the upper 'end wall an inwardly open relatively shallow annular recess having said discharge openings therein and wherein one of said xed contacts is mounted, the path of movement of one end of said rotatable contact member also being located in said recess, said recess maintaining by the dynamic action of said fluid discharge iiowing from said housing to said openings the non-coniined upper arc in the said path oi the contact member in front of said openings and directing said iiuid in optimal manner, and a pressure responsive elastic element located inside of said housing and cooperating with said fluid guiding means for delaying and lengthening the action of said fluid discharge.

11. A circuit breaker according to claim 10, wherein the elastic element disposed intermediate the ends ofthe housing is an air lled member.

12. A circuit breaker according to claim 10, wherein means are provided for selectively obturatin-g said exhaust openings.

ANDR GUILLAUME. ALBERT THIBAUDAT.

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

STATES PATENTS Number Name Date 438,118 Smith Oct. '7, 1890 1,537,352 Hilliard May 12, 1925 1,566,091 Hilliard Dec. 15, 1925 1,899,605 Baker Feb. 28, 1933 2,051,196 Barfoed Aug. 18, 1936 2,100,753 Schofield et al Nov. 30, 1937 2,239,243 Moncharnps Apr. 22, 1941 FOREIGN PATENTS Number Country Date f 833,188 France July 18, 1938 852,550 France Oct. 30, 1939

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