US2387589A - Circuit breaker - Google Patents

Description

Oct 23, 1945- F. KEssELRING ErAL 2,387,589

CIRCUIT BREAKER Filed July 18, 1938 3 s heetsmSheQ- l 0t.23,1945. F. KESSELRING mL 2,387,589

CIRCUIT BREAKER Filed July 18, 195s 5 sheets-sheet 2 Fig. J

Fig. d

as d l 57 O L E f/K 5f/ 9 QS l x 1 1 Oct. 23, 1945. F. KESSELRING ETAL CIRCUIT BREAKER IFiledJuly 18 1938 3 Sheets-Sheet 3 Patented ct. 23, 1945 UNITED STATES PATENT OFFICE mann, 'Berlin-Sieniensstadt,V Germany; vested in the Alien Property Custodian Application July 18, 1938, Serial No. 219,932 In Germany July 19, 1937 9 Claims.

The invention relates to high-capacity circuit breakers operating with an extinguishing iiuid.

An object of the invention is to ensure in such switches an effective and deiinite extinction of the arc within a very small break distance between the separating contacts by means of a minimum of constructive elements and material.

An object also is to utilize the arc occurring in high-capacity switches` for producing an intensive and highly compressedv stream of an arcextinguishing fluid.

Another object is to provide that by the eiect of the arc itself the extinction occurs either by a directed stream of a compressed iluid or by an expansive effect depending upon the particular conditions of the current to be interrupted.

An object, further, is to diminish or eliminate the accelerating` or retarding effect of the pressure within the switching chamber on the movable contact of a circuit breaker.

An object, in conjunction with one or more of the foregoing, is to obtain the desired results with relatively small switching chambers, a minimum of quenching fluid and a simple and reliable construction even in the case of circuit breakers for switching very high energies. Other objects will become apparent from the following description.

According to the invention a control device operated in response to the contact movement or the pressure within the switch chamber is provided which causes the extinguishing fluid to suddenly ow in parallel to the axis of the arc and to enclose the arc and the gaseous envelope usually surrounding the arc. In combination with a device of such construction and operation, an arc-extinguishing liquid is provided within the switching chamber, which liquid consists substantially of a conductive mixture of 60 to 80% multivalent alcohol-with 40 t0 20% water. As multivalent alcohols, glycol, glycerin, erythrite, mannite and the like have proved particularly effective. Favorable conditions are obtained, for instance, with an extinguishing liquid consisting of glycol-mixed-with water. l

The novel circuit breaker prevents with certainty any iire risk and ensures an extinction of the arc within very small distances between the contacts. In this manner it is possible to design a switch employing the liquid according to the invention smaller than has heretofore been possible, thusensuring a considerable saving in-material and' space requirement and a reduction of thev costof manufacture.

The above-mentioned extinguishing liquid, consisting of glycol and water, has the further advantage that the solidifying point lies at about to -80 and that the dissolving power as compa-red to water is very slight so that the conductivity is practically constant. Furthermore, the viscosity is far less dependent upon the temperatures than is, for instance, the case with oil.

Other features and details of the invention arementioned in the following description of the embodiments shown in the drawingsv in which- Figs. l to 4 illustrate four different embodiments by a cross section through the essential elements of the contactV elements, Figs. 5 to 7 exemp'li-fying three moreembodiments of somewhat different character, also in cross sections, and Fig. 8 represents in cross section a further way of realizing the invention.

In these gures, the same reference numerals areused for indicating similar elements.

1n Fig. l, l denotes a liquid container in which is placedY a chamber 2` whose bottom 3 is provided with *anA aperture 4 for the passage of the contact' rodl V5. The chamber 2 consists of insulating material and is provided with a partition through a hole 6 of which the contact rod 5 passes practically without the slightest clearance;

An inverted cup-like counter-contact B cooperates with thecontact rod. The counter-contact may be lirmly arranged below the aperture 4 at a-suitable distance, or it may be pressed according to another form of the invention by a spring 39 against the opening' 4 so that it practically closes the aperture temporarily and permits the flow of the liquid therethrough only when the pressure produced by the arc has exceeded a certain value.

The pressure of the gas" bubbles produced by the arc causes the liquid to flow out of the aperture il, thus forming a streaming liquid or gas sleeve whichA restricts and extinguishes the arc.-

Theaperture 4 or the bottom 3 may be provided with guiding members in order to better enforce the proper flow of the extinguishing fluid.

In the embodiment shown in Fig. 2, the chamber 2 consisting of insulating material is provided with an opening at the upper part thereof friction by the contact rod so that an auxiliary arc is ignited between the contact 8 and the intermediate contact 9, which arc forces a stream of liquid to ow out of aperture 4. As soon as the intermediate contact has reached the stops I2, the contact rod is separated therefrom, and the main arc is ignited in the neighborhood of the aperture I and is constricted by a liquid or gas sleeve formed by the liquid stream caused by the auxiliary arc and is thereby extinguished. In other words, the contact device includes two series-arranged pairs of interrupting contacts 5, 9 and l, 9 forming two series-arranged arc gaps, the intermediate movable contact member 9 being common to`both of said gaps. Said contact member 9 acts simultaneously as ar movable cover means for the aperture 4 which it covers partly during the operation, i. e. a substantially annular opening between contact member 9 and aperture 9 is formed, when said member 9 during the interrupting operation has reached its end position in which it abuts said stops I2. As a result of this arrangement the fluid stream flowing through said aperture 4 is controlled in dependence upon the operation of said movable contact 5, since the latter moves along with members in the beginning of the operation. Member 9 is then left to the control of said springs II, after contacts 5 and 9 have been separated at the end of said operation. The cross-sectional area at aperture through which the iiuid streams, is gradually decreasing during the upwards movement of member 9 with the result that the pressure of said stream in the aperture i is gradually increased, thus insuring an intensified quenching action on the arc. A discharge chamber may be formed adjacent to the switch chamber by an additional wall I3 through which the contact rod passes without clearance, which discharge chamber communicates with the outer liquid chamber either through small holes iii orvalves I5 or both, thus causing an increase in pressure so that the switching operation is effected under super-atmospheric pressure and therefore under particularly favorable conditions.

In the embodiment shown in Fig. 3, the stationary partition I6, which subdivides the switch chamber 2, has its central opening II for the passage of the contact rod 5 provided with a closure member consisting of a metal flap I8. The partition I 5 further has lateral holes I9. When separating the contacts, an arc is produced between the rod 5 and the stationary contact I. After the rod 5 has passed the aperture I'I, the arc divides itself into an auxiliary lower arc maintained between the metal flap I8 and the stationary contact 'I, and an upper or main arc between flap iS and rod 5. Owing to the pressure produced by the lower arc, which pressure cannot be reduced as now the aperture I'I is closed by the flap, the liquid is forced through the lateral holes I 9 and thence through the openingti of the switch chamber 2 so that a flow of liquid or gas is produced which constricts and extinguishes the arc.

This formv of the invention shows a further possibility Yof operating the circuit breaker under super-atmospheric pressure by connecting a pressure bottle 2which, for instance, may be lled up with carbonio acid, nitrogen, or the like-to the sealed switch chamber. This allows controlling the pressure conditions within the chamger by adjusting the additional pressure exerted on the liquid level. Y

A form of the invention with a differential piston is shown in Fig. 4. Within the switch chamber 2 is arranged the diierential piston 2| which is located in a guiding sleeve 22 in such a manner that its smaller piston surface lies at the upper part and its larger piston surface at the lower part thereof. When interrupting the circuit an increased pressure is brought about by the arc causing an upward movement of the piston against the force of springs 23 owing to the difference between the piston surfaces. The upward movement of the piston 2| causes the exv tinguishing liquid to flow from the upper part of the chamber 2 which is practically closed by the contact rod 5 into the lower space through central aperture 25, thereby constricting and extinguishing the arc drawn through this aperture.

The invention is not limited to the forms shown, instead of a differential piston a pressure may also be produced by a system of levers or in another manner. For instance, an explosive substance may be brought to ignition, thus imparting to the liquid the necessary pressure and motion. It is also possible to actuate the piston by coupling it directly with the contact rod, it being essential only that the movement of the piston produce a rapid flow of liquid through the aperture of the switch chamber through which the arc is drawn.

The liquid level is chosen preferably very high as will be seen from the drawings.

The embodiment shown in Fig. 5 is characterized by the fact that the switching chamber together with the aperture which forms the guide nozzle for the liquid stream is elastically supported in such a manner that it is movable with respect to a partition and when moved opens lateral escape orifices which form a by-pass for the nozzle and the switching chamber. The cylindrical liquid container I has metallic covers 3| and 32. The lower cover 32 carries the stationary counter-contact 'I designed in the form of an inverted cup. The movable intermediate contact9 designed as a contact rod is guided in the lower portion of the cylinder I by a frame 33 and is supported by a spring Ii. The highest position ofthe intermediate contact 9 is determined by the fact that the plate 33 comes into engagement with the partition I5 which subdivides the container into an upper space (discharge space) and a lower space (pressure space) The partition has the form of a conical valve seat. On this seat rests a mouth piece 34 shaped in a similar manner and having in its central portion an aperture 35 for the.v passage of the contact rod 5. The opening 35 serves as a guide nozzle for the ow of liquid. The mouth piece 3d is associated with another cylinder 36 of insulating material enclosing an inner chamberwhich communicates with the upper part of the container through lateral holes 31. Between the cover 3l and the upper end of the cylinder 35 isarranged a rubber ring 38.

When in contact-closing position the intermediate contact 9 is pressed into the counter-contact 'I by means of the contact rod 5. When interrupting the circuit the contact rod 5 is moved in the upward direction, the intermediate contact 9 following therod under the influence of the spring II so that an auxiliary arc is ignited Y between the lower end of the intermediate contact and the stationary contact. By means ci the Vauxiliary arc the extinguishing liquid surrounding the same is partly evaporated, thereby 4causing va great pressure resulting in an axial Asl flow of liquid through the escape orifice 35. soon as the intermediate contact has reached its uppermost position the main arc is drawn between the intermediate contact 9- and the contactrod v through the same escape oriiice 35 so that this arc is restricted by a concentric flow of liquid and is thereby extinguished under the most favorable conditions. If in the case of relatively high currents the pressure inthe pressure chamber should assume an extremely high value, the mouthpiece 34 is raised and opens an annularv gap between the partition l-f and the mouthpiece 34 so that the pressure isrelieved. Owing to the pressure-responsive control this gap remains so small that at all events a sufricient iiow of liquid through the orifice 31 is maintained, thus ensuring the extinction of the arc.

In this for'm of the invention, a very great eilicacy and reliability is obtained by means of a space saving and simple construction. It is further possible to move the contact rod 5 to a further extent so as to attain a greater break distance if desired. Under certain circumstances anaddition-al Contact break may be provided for at another point in series with the above-mentioned main contacts. rPhe metal parts are connected to advantage to the insulating parts by turning out in both parts corresponding grooves which are filled up with a solidifying material such as low melting metal or molding compounds.

The principle of construction and operation represented by Fig. 5 is not limited to the particular embodiment illustrated in this figure. It is, for instance, also possible to provide a separate pressure-equalizing valve between the pressure chamber and the discharge chamber of the switch instead of the resilient arrangement of intermediate plates and of an inner cylinder movable with respect to each other. Such equalizing valve may be similar to valve i5 in Fig. 2, except that it is to be arranged in the partition i3, as will be explained later with reference to Fig. 8. The intermediate contact may also be designed similar to that of Fig. 2, namely in the form of a double cup, the counter-contact having then the form of a contact rod. The two cup-shaped hollows of the intermediate contact then enclose the ends of two opposite and coaxial contact rods. The upper and lower hollows of the contact may, if desired, be so closed with respect to each other as to be liquid-tight.

This improvement presents under certain circumstances considerable advantages also when using insulating extinguishing liquids such as oil or the like.

Some other modifications possible in a circuit breaker of the type exemplified by Fig. 5, are the following. The resilient support of the inner chamber need not be effected by a rubber ring 38 but can be produced by other resilient means, for instance, by springs. The resilient members are arranged to advantage in such a manner that they lie outside the range of the het gases and therefore are not impaired by repeated switching operations. It is particularly advantageous to design the upper contact 5 as a pressure contact and the lower contact l' in the form of a cup, in which case a greater contact pressure may be ensured on the upper contact by the spring Il. The spring itself may be insulated with respect to the lower contact l or with respect to the intermediate contact il. It may be particularly convenient to arrange the additional escape orices (valve ring) as near as possible to the nozzle'- openi'ng 35 sothat the desired flow of 'liquid or vapor is disturbed as little as possible by the operation of the valve.

It is further advantageous if in the above-described breakers as well as in the following embodiments they separation of the contacts drawing the main arc is so limited that at the proper moment the arc has a length most favorable for the extinction, which length can easily be determined for any type of circuit breakers. In this case it is possible to separate the contacts drawing an auxiliary arc in series with the main arc to such an extent that a suiicient gap free, if necessary, of surface leakage is created.

By such an arrangement the performance of the arc and therefore the ionization of the main l arc is kept very small as compared to the arrangements hitherto known so that the current may be interrupted with certainty.

It is also advisable to control the movement of at least one of the two electrodes forming the main switching gap in such a manner that during the interruption the electrode is spaced a distance from the nozzle-like aperture at which the blow-out effect of the nozzle is most eihcacious.

Such an arrangement allows under certain circumstances to continue the movement of the other electrode even beyond the so-called optimum distance between the contacts without impairing the blow-out effect.

The embodiments illustrated in Figs. 6, 7 and 8 are further examples of circuit breakers in which at least one of the switching chambers for the main and auxiliary arcs is provided with pressure-responsive resilient elements so that in the case of excessive interrupting capacities the chamber is not destroyed.

In the embodiment of Fig. 6, the lower chamber is resiliently closed by one of the main contacts, while in the breakers according to Figs. 7 and 8 a valve construction resembling that of Fig. 5 is employed. In each oi these four cases, the breaker forms a so-called resilient chamber. Such a chamber makes it possible to extinguish the arc with relatively low currents by a pressure-responsive opening of escape orifices which produces a sudden relief of pressure in the sense of the so-called expansion circuit breakers. This represents a valuable improvement insofar as with a relatively low current the flow of the eX- tinguishing medium caused by the auxiliary arc may not be sufciently strong to alone ensure the extinction of the arc. In this manner the further advantage is obtained in that during the extinction a static pressure is maintained, whereby comparatively high voltages may be controlled or a smaller extinguishing distance may be chosen for a given voltage.

In the embodiment of Fig. 6, the switching chamber proper is formed by the upper portion 4| of the insulating casing. Within the chamber is arranged a movable wall 33 carrying an intermediate contact 9. The wall 33 is pressed in the upward direction by a spring H. The lower portion 42 of the casing contains the stationary contact 8. An insulating plate 43 is arranged between parts 4I and 42 and is provided with a passage 44 for the intermediate contact S. 'I'he parts 4|, 42 and 43 may be secured rigidly to one another by fastening means 45, or they may be connected by resilient means which allow the parts to separate from one another in response to pressure so that the arrangement represents a so-called elastic chamber as employed in expansion circuit breakers. In the intermediate plate 33 are provided lateral apertures 4tV which ensure a passage of the extinguishing medium. The movement of the intermediate plate in the upward direction is limited by stops I2 to an amount for which the most favorable extinguishing distance exists between the contact 9 and the counter-contact 8.

When switching-in the circuit breaker, the contact rod 5 engages the upper end of the intermediate contact 9 in the form of a pressure contact and entrains the intermediate contact 9 and presses it into the cup-shaped Contact 8.

When interrupting the circuit the movable contact rod 5 moves in the upward direction. In this case the contact 9 follows under the action of the spring H so that the contacts 9 and 8 are separated from each other, thus producing the main arc between each other. However, when the stop I2 is reached, also the contacts 9 and 5 are separated so that an auxiliary arc is ignited. In this manner the extinguishing liquid in the chamber of part l now closed by the counter contact 8 evaporates, thereby producing a pressure. Under the influence of this pressure the contact 8 moves in the downward direction and uncovers the opening 44 of the plate 43 so that the extinguishing liquid begins to flow through the opening 44 thus surrounding and constricting the main arc ignited between the contacts 8 and 9. This quenching of the arc is especially effective since the best extinguishing conditions are attained by maintaining a favorable distance between the contacts 8 and 9. The eiect can further be improved by employing a static super-atmospheric pressure as described above with reference to Fig, 3. During this quenching operation, the contact rod 5 moves out of the chamber 4I so that a switching gap free of surface leakage and having a length depending upon the operating voltage and the conductivity of the extinguishing medium is obtained.

In the embodiment shown in Fig. 7, the casing forming the switching chamber consists of three parts 4l, 42 and 43. 5 and 1 are the main contacts, and 9 an intermediate contact carried by a movable plate 33 which is held against stops i2 by a spring Il. Part 4I of the casing forms a partition I6 with a central, nozzle-like aperture 44 for the passage. I-Iere also the contact device including the contacts 5, l and 9 forms two series-arranged pairs of interrupting contacts.

Part 4i of the casing is closed by a wall 48 arranged above the partition I6. The wall 48 forms a conical valve-like seat carrying a valve disk 49 which is pressed into the closed position by a spring 38. In this manner the casing forms an elastic chamber which upon exceeding a given pressure is opened by the upward movement o the valve disk 49.

When breaking the circuit the contact 9 follows the contact rod 5 under the action of the spring H till it reaches the stops l2; i. e. till the contact 9 is in the most favorable extinguishing position with respect to the nozzle 44. During this first part of the Switching-out o eration an auxiliary arc is produced between the contacts l and 9. Upon the further movement of the contact rod 5 the latter separates from the intermediate contact 9 and draws the rnain arc;

through the nozzle. At the same time the previously ignited auxiliary arc causes a stream of fluid to flow from the lower portion of the casing through the nozzle 44, thus extinguishing the arc. If with small current intensities an extinction of the arc does not occur in this manner a sudden relief of pressure is initiated -by the lifting of the valve disk 45 or by the removal of the rod 5 out of the upper chamber aperture so that an interruption of the arc occurs by an expansive effect similar to that occurring in the so-called expansion circuit breakers.

A hollow contact rod 5 is employed to advantage which when its end passes through the nozzle plate I6 establishes a connection with the atmosphere through a bore 59 and an opening 5l, thereby facilitating the escape of the gases. It is of advantage that spring il urges the movable contact 9 upward when contact 5 is raised, and that said movable contact partly covers the aperture 44, when said contact assumes its end position. Thereby the same control of the fluid stream through aperture 44 is obtained as in the embodiment of Fig. 2. As extinguishing uid to be provided in the lower part of the casing, not only a conductive one may be used but also oil or a non-inflammable insulating liquid.

In the case of the circuit breaker types so far described the extinguishing liquid is intensely heated by the arc and evaporated at least partially, thereby causing a considerable increase in pressure. In this case the increase in pressure is at least partially dependent upon the corresponding current to be interrupted. This increase in pressure also acts on the moving contacts in the sense of acceleration or retardation, depending upon the direction of motion. Consequently, the speed of the switching operation which is brought about by outer mechanical means, gears, release of energy accumulators such as springs or the like, will diier considerably depending upon the intensity of current at which the interruption occurs. If at high intensities of current the speed of motion and the distance between the contacts up to the moment of the interruption of current are increased by an additional acceleration, the power of the arc may be increased to such an extent that the extinguishing conditions are impaired. If the pressure acts in the sense of a retardation of the contact motion, the pressure may become so great that the necessary minimum distance between the contacts is attained very late, thus also complicating or preventing the interruption.

According to a further improvement this drawback may be removed by providing the switching chamber with a movable element of approximately the same surface as the movable Contact rod, which element is so coupled to the contact rod as to move in opposite direction. Thus the influence of pressure on the motion of the contact rod is completely eliminated. A further result is that within the switch chamber a decrease in volume due to the contact movement is avoided. II'his is advantageous, particularly in the case of a comparatively small switch chamber and when carrying out switching operations at a low current intensity, because the pressure developed by the formation of the arc isutilized to the full extent.

An embodiment of the last-mentioned form of the invention is shown in Fig. 8. The elements arranged in the switching chamber proper are constructed similar to those of Fig. 5, except that an additional pressure relief valve l5 is provided in the partition IS in order to protect the switch against excess pressure occurring in the liquid-containing lower chamber 53 of the casing. denotes a plunger, for instance of insulating material, which is guided in a bore 54 communicating with the switch chamber 53. The contact rod 5 and the plunger 55 are so coupled with each other through a lever 51 and connecting links 56 and 58 as to move in opposite directions; Instead of a lever mechanism, other couplings may Abe used, such as gear racks, gear wheels and Vsimilar' transmission members. It is also possible to give the contact rod and the compensating member a different cross-section and to compensate this difference by a corresponding transmission of the movement (lever arm).

The switch of Fig. 8 lhas also two series-arranged pairs of interrupting contacts forming two series-arranged arc gaps and a movable intermediate spring-urged, contact member S partly covering the aperture through which the 4extinguishing ilu'id stream iiows, when said member 9 is in its upper end position. The controlling function with respect to the arc-extinguishing fluid stream is the same as in the embodiments in Figs. 2 and 7.

Also in the case of other circuit breaker types, such as vpressure gas circuit breakers or oil circuit breakers in which the pressure caused by the are may act on the movable contact in the sense of an acceleration or retardation, considerable advantages may be obtained according to the last-described form of the invention.

What is claimed is:

l. In a high-capacity circuit breaker comprising a container provided with a conductive .arcextinguishing liquid and having an upper discharge chamber and a lower pressure chamber separated by a partition and communicating with each other through an aperture, a stationary contact rod and a movable intermediate contact body arranged in said pressure chamber, 'spring means tending to move said intermediate contact body towards said aperture, a movable Contact rod arranged to pass through said aperture so as to draw a main arc through said aperture after an auxiliary arc is initiated in said pressure chamber between said stationary contact rod and said intermediate contact body,'

said intermediate contact body having two opposite cup-shaped recesses for engaging said contact rods respectively, and pressure-relief 4main arc.

2. A heavy-duty circuit breaker, comprising a container, a given quantity of conductive extinguishing liquid disposed in said container and composed of materially over up to about 89% multivalent alcohol with materially less than 40% and down to about 20% of water, and composite interrupting means for drawing an arc in said container and causing a fluid stream developed from said liquid to axially envelop and .constrict said arc, said container arranged immediately surrounding said interrupting means being substantially closed so as to limit the amount of liquid Ioperative during the switching operation to said quantity, said interruptving means including a partition dividing said container into a pressure chamber and a discharge chamber and having an aperture connecting 'said chambers, a contact device forming two series-.arranged arc gaps and arranged in said container, lso as to have one of said gaps disposed within said pressure Chamber and said other gap extending through said aperture, whereby te arc formed by said gap in said pressure chamber is caused to produce said fluid stream and 'to force it out of said aperture and axially around the arc of said other gap.

3. A heavy-duty circuit breaker, comprising a container, a given quantity of conductive extinguishing liquid disposed in said container and consisting substantially of multivalent alcohol in an amount of materially more than 60% up to about mixed with materially less than 40% down to about 20% of water, and composite interrupting means for drawing an arc in said container and causing a fluid stream developed from said liquid to axially envelop and constrict said arc, said container arranged immediately surrounding said interrupting means being substantially Vclosed so as to limit the amount of liquid operative during the switching operation to said quantity, said interrupting means including a partition dividing said container into a pressure chamber and a discharge chamber and having .an aperture connecting said chambers, relatively movable contact means in lsaid container forming two series-arranged pairs of interrupting contacts, one of said contact pairs being arranged to draw when in operation an arc through said aperture, said other contact pair being arranged in said pressure chamber, said latter contact pair including a movable contact member arranged to partly cover said aperture when in interrupting operation so as to close said pressure chamber except for a substantially annular opening between said movable member and said aperture in order to cause the arc between the contact pair within said chamber to yproduce said iiuid stream and to force it through said annular gap around and axially along the arc occurring at said other contact pair,

4. A heavy-duty circuit breaker, comprising a container, conductive extinguishing liquid disposed in said container and consisting substantially of multivalent alcohol in an amount of materially more than 60% up to about 80% mixed with materially less than 40% down to about 20% of water, and composite interrupting means for drawing an arc in said container and causing a iiuid stream delevoped from said liquid to axially envelop and constrict said arc, said interrupting means including a partition disposed in said container to form an upper discharge chamber and a lower pressure chamber, said partition having a central aperture through which said two chambers communicate with each other, a contact device disposed in said container for forming two series-arranged arcs, said device comprising a movable contact member passing through said aperture so as to draw when in operation one of said arcs through said aperture and contact means cooperating with said member for drawing said second arc within said pressure chamber, and pressure-responsive valvelike closure means associated with said contact device and tending to cover said central aperture so as to release through said aperture and in the axial direction of said first arc an arcquenching gas stream produced in said pressure chamber by said second arc from said liquid.

5. In a high-capacity circuit breaker comprising a container provided with a limited quantity of conductive arc-extinguishing liquid and being substantially closed so as to limit the liquid operative during the breaker operation to said quantity, said container being subdivided and having a pressure chamber, an intermediate discharge chamber, and an outer discharge chamber, said quantity of liquid being disposed to normally flood and cover said pressure chamber and said intermediate chamber completely while partly filling said outer discharge container, said pressure chamber and said intermediate discharge chamber having a common wall portion, said wall portion having an aperture forming the only operative communication between said pressure chamber and said intermediate discharge chamber, a stationary contact and an intermediate contact arranged in said pressure chamber, spring means tending to move said intermediate contact towards -said aperture, a movable contact arranged so as to pass through said aperture when in contact-closing position, whereby when opening the breaker an arc produced in said pressure chamber between said stationary contact and said intermediate contact causes a stream of arc-quenching iiuid to flow through said aperture into said intermediate discharge chamber so as to axially envelop a second arc formed between said intermediate contact and said movable contact, said intermediate and said outer discharge chamber also having a common wall portion and pressure relief means arranged in said latter wall portion and forming a, fluid communication between said discharge chambers within said container.

6. In a high-capacity circuit breaker comprising a container provided with a conductive arcextinguishing liquid and having a partition so las to form an upper discharge chamber and a lower pressure chamber, said partition having a central aperture forming the only open communication between said two chambers when the breaker performs its interrupting operation, a contact device disposed in said container and comprising an actuable movable contact, an intermediate contact and a substantially stationary contact for forming two series-arranged arcs, said movable contact member being arranged so as to pass through said aperture for drawing when in operation one of said arcs through said aperture, and said intermediate and stationary contacts being arranged in said pressure chamber for drawing said second arc within said pressure chamber, spring means for causing said intermediate contact to follow the movement of said movable contact, stop means disposed in the path of said intermediate contact for stopping the movement of said intermediate contact in a position where said intermediate contact restricts the passage formed by said aperture to an annular gap so as to cause the gas stream produced from said liquid by said second arc to axially envelop said iirst arc, said movable contact consisting of an axially displaceable rod and having a central bore open towards said pressure chamber and a lateral opening communicating with said bore, and means associated with said container for covering and uncovering said lateral opening in dependence upon the position of said movable contact so as to establish at the end of each interrupting movement of said movable contact a free communication between said discharge chamber and the outside atmosphere through said central bore and said lateral opening, whereby the gas is allowed to quickly expand after said enveloping gas stream has been eective.

7. In a high-capacity circuit breaker, in combination, a container having a partition so as to form an upper discharge chamber and a lower pressure chamber, an alcoholic extinguishing liquid with less than 40% water disposed in said container so as to completely flood said pressure chamber, said partition having a central aperture forming substantially the only communication between said two chambers when the breaker is in interrupting operation, a contact device disposed in said container for forming two series-arranged arcs, said device comprising a movable contact member passing through said aperture so as to draw when in operation one of said arcs through said aperture and contact means cooperating with said member for drawing said second arc within said pressure chamber, pressure-responsive valve-like closure means Y associated with said contact device and tending to restrict the uid passage through said central aperture so as to release through said aperture and in the axial direction of said rst arc an arc-quenching gas stream produced from said liquid by said second arc, and pressure-relief means associated with said movable contact member and controlled in kinematic dependence upon the interrupting movement of said contact member so as to establish a free communication between said container and the surrounding atmosphere at the end of each interrupting operation in order to cause a quick expansion of the vaporized liquid after said gas stream has been eective.

8. A high-capacity circuit breaker comprising a switching chamber partly lied with a limited quantity of conductive extinguishing liquid, a stationary contact in the lower portion of said chamber, a movable contact arranged so as to be removed from said liquid when in interrupting operation, the liquid-containing portion of said chamber having a relatively small volume as compared with the volume of the portion of said movable contact submerged in said liquid when said movable contact is in contact closing position so that the removal of said movable contact tends to appreciably lower the level of said liquid in said chamber, a counteractingr member arranged movably with respect to said liquid quantity in order to control said liquid level, and a mechanism connecting said counteracting member with said movable contact for operating said member in opposition to the movement of said movable contact so as to compensate the effect of the contact movement cn the liquid level.

9. In a high-capacity circuit breaker, in combination. a container having a partition dividing said container into a pressure chamber and a discharge chamber and having an aperture through which said chambers communicate, an alcoholic extinguishing liquid disposed in said pressure chamber, a movable contact rod arranged in said container so as to extend through said aperture when in contact-closing position and to draw an arc through said aperture when in interrupting operation, movable means operatively connected with said contact means for restricting the fluid passage through Said aperture during the contact-opening period in order to force through said aperture a gas stream developed from said liquid in said pressure chamber and enveloping said arc, the quantity of said der to maintain said liquid level substantially constant during the movement of said Contact rod, said additional chamber being connected with the bottom portion of said pressure chamber.

FRITZ KESSELRING. FRIEDRICH GIEFFERS. WERNER. KAUFMANN.

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