US2614193A - Air blast circuit breaker with switching resistance - Google Patents

Description

Oct. 14, 1952 M; CREMER AIR BLAST CIRCUIT BREAKER WITH swTT-CHING RESISTANCE Filed July 18, 1950 2 Sl-IEETS-SHEET l 'INV ENTOPQ.

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Pme am E19 Patented Oct. 14, 1952 AIR BLAST CIRCUIT BREAKER WITH SWITCHING RESISTANCE Michel Cremer,y Paris, France, assignor to Forges et Ateliers de Constructions Electriques de Jeumont, Paris, France, a corporation of France Application July 18, 1950, Serial No. 174,524 In France August 2, 1949 (Cl. 20D-148) 9 Claims.

In certain air blast circuit breakers and particularly in those which use switching resistances, the interruption is carried out in a plurality of successive stages. These stages comprise for example in each phase: the preliminary separation of contacts which may open without an arc, the rst separation of contacts which produces an arc in parallel with a switching resistance, then after the extinction of `this first arc, thek second separation of contacts which produces a residual arc in series with the Asaid resistance, and after the nal extinction of this residual arc, the complete cutting of the vcircuit preferably in such a way that a clearly visible indication of the position of the circuit breaker'` is given.

All these operations should follow in a positive unchangeable order during the opening of the circuit and in the inverse order during the closing thereof with eachr of'them taking place at a predetermined time. The various elements of the apparatus should be simple and strong. with shapes and dimensions appropriate from the aerodynamic viewpoint, as well as from the viewpoint of mechanical and electrodynamical forces.

It is also important to reduce to a minimum the displacement whichy is effected by the blown arcs which may present difficulties with strong currents. It is also necessary to avoid wear of the active elements ofthe vapparatus and for this purpose to reduce as far as possible the total duration of the arcs. f

Ithas already been proposed to use in air blast circuit breakers a single. movable 'contact element cooperating successively with several fixed contacts and operating then asa disconnecting switch. However apparatuses of this Vtype are not capable of fuliilling allthenecessaryfconditions which have been enumerated. n

In certain of these devices use is made for example, of a transverse blowing carried out by means of arc chutes which can not operatesatisf actorily under high voltages. In certain others, the use of ka single movable contact results in costly and complex structures with separate disconnecting switches or in great difficulty in using switching resistances.

An object of thepresent invention is to provide a very simple structure which permits fulfilling all the conditions indicated above while using a single movable contact elementfor arc interruption and disconnection of-circuits. n

A further object of the invention is to embody all the elements ofthe arcing chamber in appropriate aerodynamic shapes, to reduce the weight and inertia of the single movable piece, to facili- 2 tate insulation and to simplfy the construction of circuit breakers.

Applied preferably to air blast circuit breakers with axial blowing, the invention is distinguished particularly by the fact that in each phase the fixed contact which forms the first arc in parallel with the switching resistance is entirely enclosed in a central electrode, which is located in front of the nozzle, while the iixed contact provided in order to form the second arc in series with said resistance is located in the neighborhood of the nozzle to which it is connected electrically, these two fixed contacts cooperating successively with a movable contact rod located and directed in such a way as to reducefto a minimum the movements of the iirst arc and acting at the end of its travel as a disconnecting switch which is driven towards the outside of the arcing chamber.

With the above and other objects which will become apparent from the detailed description below, various forms of the invention are shown in the drawings in which:

Fig. 1 is a vertical cross-sectional view of one manner of constructing the invention;

Fig. 2 is a schematic view illustrating one manner of mounting the above device with the live parts located in back of a partition;

Fig. 3 is a view similar to Fig. 1 showing a modied construction; and

Fig. 4 is a similar view illustrating a still further modiflcation.

In the various figures like reference characters indicate like parts. i

In Fig. 1 there is shown a compressed air receptable I, normally closed by an air blast valve 2 and carrying two insulators 3 and 4. the insulator 3 being hollow and provided with an air blast channel 5.

The upper end of the insulator carries a metal-v lic collar E, supporting by means of a hollow insulator 'I a metallic cup 8 provided with a nozzle 9 for axial arc blow-out. The collar 6 is connected by radial arms I 0 to a central electrode I I carrying an arcingtip' I2 of refractory metal designed to fix the root of the arc in front of the neck of the nozzle 9.

In the interior of the central electrode II is located the first fixed contact I3 having an appropriate tubular form and cooperating with the movable contact rod I4. `Its opening is located in the immediate neighborhood of the centrally located'arcing tip I2; The movable rod I4 passes through a second xed contact I5 similar to the contact I3. The' rod I4 is mounted onv a pivoting arm I6 whose pivot II is mounted on the insulator 4. The second fixed contact I5 is located in an enlargement extending exteriorly of the metallic cup 8 and is adjacent the neck of the nozzle 9 with which it is in electrical interconnection as shown.

The pivoting arm I6 is provided with a contact element I8 of appropriate form cooperating with a xed contact I9 mounted on collar 8. It has a control lever Z of insulating material which is operated in any suitable way by a control mechanism 2| of any type whatsoever, for example, a compressed air piston, not shown.

The circuit connections A and B of the corresponding phase are connected to the terminals 22 and 23 located respectively upon the pivot I'I' and the collar 6. A switching resistance 24 is connected between the terminal 23 and the body of the nozzle 9. The exhaust channel 25 comprises a suitable damper and deionizer 2S supported for example by a grid 21.

In operation, the interruption of the circuit between A and B, controlled by the mechanism 2|, starts with the separation of the contacts I8 and I 9 which takes place without arcing and with the opening of the valve 2 which is effected by a cam 3| which may be of the ratchet type and by the levers 29 and 3D, keyed upon a common shaft 29A. The rod I4 then leaves the contact I3 and forms the first arc which is shunted by the switching resistance 24. This arc is produced in the immediate neighborhood of the refractory element I2 of the central electrode I I, and it has only to make a slight movement in order to reach its final position in the axis of the nozzle 9 in vhich it is efficiently blown out.

After the denite extinction of the rst arc the current which is limited by the switching resistance 2d is interrupted by the separation of the contacts I4 and I 5. The valve 2 can be closed again at this moment, the lever 3U becoming disengaged from the cam 3i, and the residual pressure which still exists in the rupture chamber producing the blowing out of this residual arc by an air blast across the Contact I5.

The movable contact I 4 continues the movement to the exterior of the arcing chamber up to the nal position I4 shown in dotted lines in which complete disconnection of the circuit is secured and a very clear visual indication of the open position of the circuit breaker is given.

The central electrode I I is relatively large and has an appropriate substantially ovoid aerodynamic form and its end I2 is located in optimum position. The insulator 'I and all the other elements have very simple forms which are strong and adapted to their respective functions.

In the case of moderate rated currents the contacts I8 and I9 may be eliminated. The apparatus described may be mounted according to Fig. 2 wherein the circuit breaker is suitably fixed upon a vertical partition 28 in such a way that all its live parts at high voltage are located at one side of such partition.

According to the modification shown in Fig. 3 the insulator 4 of Fig. l is eliminated and the pivot I 'IA is mounted upon a collar 22A which divides the tubular supporting insulator 3 into two portions 3A and 3B.

In the arrangements of the preceding figures which have a substantially identical structure of the electrodes, the first arc which is formed between the Contact rod I4 and the xed contact I3 has to be transferred to the body 0f the cup 8 in order to then traverse the neck of the nozzle 9 and to attain the axial position between the tip I2 and the grid 21. This movement of the arc is carried out normally without difiiculty but in certain cases, especially when the currents are heavy, it may be desirable to avoid it completely.

This result is obtained in the arrangement shown by Fig. 4 where the contact rod I4 is directed in such a way as to pass through the neck of the nozzle and where the second fixed contact I5 is mounted behind the nozzle. With such an arrangement, the first arc, which is drawn between the contact elements I3 and I4, is formed directly in its final axial position in which it is blown out. Thereby any loss of time due to its movement and commutation is eliminated; this arc is no longer obliged to pass to another electrode, nor to be displaced, and such elimination of all arc movements manifestly improves the performance of the circuit breaker.

The constructions which have been described secure particularly the following advantages:

l. A single movable element assures positivelf.7 the successive order of all operation stages.

2. All the elements of the circuit breaker are simple, strong and aerodynamic, including the insulating elements.

3. The movements of the arcs are reduced to a minimum which enables to effect an efficient blow-out as rapidly as possible.

4. The length of the contact rod being slight, the weight and the inertia of the movable parts are reduced which diminishes the mechanical forces of acceleration and deceleration.

5. The operational travel of the movable equipment which corresponds to the interruptions of the arcs being relatively slight, the speed thereolc may be reduced which also diminishes mechanical stresses and facilitates automatic reclosing.

6. The rotating arm which supports the movable contact is relatively short and the overall size of the circuit breaker is reduced.

7. The disconnection which is made at the exterior of the apparatus is clearly visible.

It is thought that the invention and its advantages will be understood from the foregoing description and it is apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing its material advantages, the forms hereinbefore described and illustrated in the drawings being merely preferred embodiments thereof.

I claim:

'1. In an air blast circuit breaker of the conventional type having two fixed contacts interconnected by a resistance, a movable cooperating contact adapted to form successively two arcs and a metallic nozzle of the axial type for blowing out the first of said arcs, means for improving the operation and simplifying the design comprising a relatively large central electrode of substantially ovoid aerodynamic form connected to one pole of the external circuit, mounted coaxially with said nozzle and adapted to enclose the rst of said fixed contacts which is positioned in such a direction that the inlet opening of said rst Contact is located close to the axis of said nozzle, an arcing tip fixed axially upon said electrode at a suitable distance from said nozzle, and a metallic extension on a side of said nozzle adapted to enclose the second of said fixed contacts in electric connection with said nozzle, said movable contact being pivoted for separating from both said fixed contacts in such a direction that the first arc is formed in the vicinity of said arcing tip.

2. In an air blast circuit breaker of the conventional type having two fixed contacts interconnected by a resistance, a movable contact element cooperating with both said fixed contacts to form two arcs and an axial nozzle of metal for blowing out the first arc, an arrangement comprising a cup-like metallic arcing chamber carrying said nozzle, a relatively large central electrode of substantially ovoid aerodynamic form mounted coaxially with said chamber and said nozzle and adapted to enclose completely the first of said fixed contacts which is mounted in such a direction that its opening is located near the axis of said nozzle, an arcing tip carried centrally by said electrode at an optimum distance from said nozzle, a metallic collar carrying said central electrode, a tubular insulating element interposed between said collar and said arcing chamber and connected to one pole of the external circuit, a metallic lateral enlargement upon said nozzle adapted to enclose the second of said fixed contacts in electrical connection with said nozzle and an arm carrying said movable contact element, said arm being pivoted in such a way that the path of said contact element differs from the said axis and that the first arc is formed by said contact element at a short distance from said arcing tip.

3. An air-blast circuit-breaker of the conventional type having two fixed contacts and a resistance therebetween, comprising a cup-like arcing chamber of metal an axial-type blowout nozzle of metal connected to and coaxial with said chamber, a relatively large central electrode of substantially avoid aerodynamic form located in the axis and in front of said nozzle, a first fixed contact entirely enclosed in said electrode in a position which is not coincident with said nozzle axis, a fixed arcing tip on said electrode adjacent said first fixed contact and located in the axis of said chamber at an optimum distance with relation to said nozzle, a collar carrying said central electrode and connected to one pole of the external circuit; tubular insulating means interposed between said collar and said chamber, a metallic enlargement upon said nozzle, a second fixed contact located within said enlargement and connected to said nozzle, and a movable contact element adapted to separate successively from said fixed contacts in such a direction that the first arc is formed in the vicinity of said axial arcing tip.

4. An air-blast circuit breaker of the type forming two arcs per phase, the first arc being shunted by a resistance, comprising a metallic arcing chamber, an axial type metallic blow-out nozzle for the first arc, a relatively large central electrode of substantially ovoid aerodynamic form located in the common axis of said chamber and of said nozzle, a first fixed contact enclosed in said electrode in a position which differs from said axis, whereby the'inlet of said first fixed contact is situated in the near vicinity of said axis, a centrally located fixed arcing tip on said electrode in front of said nozzle, insulating means between said electrode and said nozzle, and a movable contact element separating successively from said fixed contacts in such a direction that said first arc is formed at a short distance from said arcing tip.

5. In an air blast circuit breaker of the conventional type forming successively two arcs and having a first and a second fixed contact interconnected by a resistance, a movable contact element cooperating with both said contacts, a single axial nozzle of metal for blowing out the first arc and a pivoting arm supporting said contact element, means for improving the performance and simplifying the design, comprising an arcing chamber of metal, a relatively large central electrode of substantially ovoid aerodynamic form fixed in the axis of said chamber in front of said nozzle and enclosing completely the first of said fixed contacts which is connected to a terminal, an arcing tip located centrally upon the top of said electrode adjacent said first contact, an exterior projection upon said nozzle enclosing the second of said fixed contacts, a tubular insulator located between said nozzle and said central electrode and means for pivoting said arm to withdraw said contact element from said arcing chamber in such a direction that the first arc is formed in the vicinity of said arcing tip.

6. In an air blast circuit breaker of the conventional type forming successively two arcs and having a first and a second fixed contacts interconnected by a resistance, a movable contact element cooperating with both said contacts, a single axial nozzle of metal for blowing out the first arc and a pivoting arm supporting said contact element, means for improving the performance and simplifying the design, comprising a relatively large central electrode of substantially ovoid form located axially in front of said nozzle, said electrode enclosing fully said first fixed contact in a position differing from the axis of said nozzle, a metallic collar supporting said central electrode, an arcing tip placed axially upon said central electrode adjacent the outlet opening of said first fixed contact, said nozzle being of metal and having an exterior enlargement enclosing said second fixed contact, a hollow insulator interposed between said nozzle and said metallic collar, operating means for withdrawing said contact element from said fixed contacts in a direction which differs from the axis of said nozzle, at relatively reduced speed to assure the interruption and the visible disconnection of the circuit, whereby the first arc is formed near said arcing tip, said pivoting arm having an additional movable contact and said collar having a fixed contact -to cooperate with said additional movable contact, said additional contacts being adapted to open before the formation of said first arc.

7. In an air blast circuit breaker of the conventional type forming successively two arcs and having a first and a second fixed contacts interconnected by a resistance, a movable contact element cooperating with both said contacts, a single axial nozzle of metal for blowing out the first arc and a pivoting arm supporting said contact element, means for improving the performance and simplifying the design, comprising a relatively large central electrode of ovoid aerodynamic form located axially in front of said nozzle, said electrode enclosing fully said first fixed contact in such a position that the inlet opening of said first contact is located near the axis of said nozzle, a metallic collar supporting said central electrode, an arcing tip placed in the axis of said nozzle upon said central electrode adjacent the said opening of said rst fixed contact,`said nozzle being of metal and having an exterior enlargement enclosing said second fixed contact, a hollow insulator interposed between said nozzle and said metallic collar, operating means for withdrawing said contact elernent from said fixed contacts in a direction not coincident with said axis at relatively reduced speed to assure the interruption -and the visible disconnection of the circuit,

whereby the rst arc is formed in the vicinity of said arcing tip, a second insulator and said pivoting arm being pivoted upon said second insulator.

8. An air bles?l circuit breaker as seil forth in claim 5 having a tubular air inlet insulator wherein said pivoted arm is mounted upon a. collar dividing said inlet; insulator 1n two parts.

9. An air blast circuit breaker as set fort-h in claim 5, wherein the movable Contact element is positioned to traverse the neck of said nozzle whereby the rst arc is formed approximately in its nal blow-out position.

MICHEL GRENIER.

REFERENCES CITED The following references are of record in the le o'f this patent:

UNITED STATES PATENTS Number Name Date 2,365,134 Amer et al. Dec. 12, 1944 FOREIGN PATENTS m Number Country Date 652,800 Germany Nov. 8, 1937 811,219 France Jan. 14, 1937

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