US2261720A - High power circuit breaker - Google Patents

Description

Nav. 4, 1941.

P. DUFF'ING ET AL HIGH POWER CIRCUIT BREAKER Filed Dec. 19, 1959 5 Sheets-Sheet l f a e S R ww fin N Z m V m m W. PM

I (I II n WITBTESSES:

Patented Nov. 4, 1941 UNITED STATES PATENT OFFICE.

HIGH POWER CIRCUIT BREAKER Application December 19, 1939, Serial No. 310,024 In Germany December 9, 1938 15 Claims.

This invention relates to circuit interrupters and, more particularly, to circuit breakers of the ultra-high voltage, high power, liquicl-immersed type.

In the transmission of electrical power over long transmission lines, the tendency in recent years has been toward higher voltages in order to minimize line losses. Paralleling the advance in transmission efficiency, electrical engineers have also improved systems stability by the provision of high speed circuit breakers which are capable of clearing a fault on a 287.5 k. v., 60 cycle line in from 2.5 to 3 cycles. This high speed operation under the conditions named has been obtained in the past by the use of a multiple break interrupting structure employing from 8 to 10 breaks for each phase. The multiple break interrupter has the disadvantage in that it is complicated in design and, consequently, costly to construct and maintain.

The principal object of our invention is to provide a high voltage, high speed circuit breaker of simple and economical construction.

A further object of our invention is the provision of an interrupting structure for circuit breakers capable of opening and withstanding the electrical stress when opened of a circuit up to at least 400 to 600 k. v.

A more specific object of our invention is the provision of arc-extinguishing means of improved design wherein an arc is drawn in an elongated arc passage, a portion of which is of length corresponding to substantially the minimum contact separation necessary to avoid reignition of the arc and of cross-section to avoid substantially any arc-extinguishing influence, whereas the remaining portion of the arc passage has a configuration which produces an effective arc-extinguishing influence as well as to provide an insulating surface capable of withstanding ultra-high voltage.

Another object of the invention is to improve the arc-extinguishing operation of high power, high voltage circuit breakers by the utilization of a liquid impedance arranged to be automatically inserted in series with a portion of the arc.

Theinvention also contemplates improving the circuit interrupting function of arc-extinguishing means by utilizing the gas pressure from the arc to circulate arc-extinguishing liquid past the stationary contact in such a manner as to efliciently remove the arc gases from the region of the tationary contact.

Still another object of our invention is to provide an improved circuit breaker Whose structure 55 which completely encloses a circuit interrupting unit and the operating mechanism therefor, further provides economyofspace and in the use of insulating liquid. In keeping with this object it is proposed to provide a hollow column having several insulator sections, the upper one of which is filled with liquid and houses the arcextinguishing element, whereas the lower ones serve as supports and house in part the operating mechanism and are filled only in part with insulating liquid.

It is also an object of our invention to provide an improved operating mechanism for a multiple phase, high power, high voltage circuit breaker capable of highspeed operation.

A further specific object of the invention resides in the provision of a more effective equalization of the operating forces on each phase of a multiple phase operating mechanism which employs the combined advantage of hydraulic and compressed air operating means.

Other objects and, advantages will appear in the following description when taken in connection with the accompanying drawings, in which:

Figure 1 is an endelevational view of a threephase circuit breaker. embodying the elements of our invention;

Fig. 2 is a side elevational view of the circuit breaker of our invention;

Fig. 3 is a sectional view of the upper end of one of the breaker columns housing the circuit interrupting structure;

Fig. 4 is a sectional view drawn to a smaller scale of the lower portion of one of the breaker columns which houses part of the operating mechanism and serves to insulate the interrupting structure from ground;

Fig. 5 is a sectional View through the base of the interrupter shown in Fig. 1 and illustrates partially in schematic form another part of the breaker operating mechanism; and

Fig. 6 illustrates an insulating shell disposed about a shield member for one of the contacts of the interrupter.

Referring to the drawings, the reference numeral l designates three metallic support structures, one for each phase, and upon which are mounted in spaced relation columns 9 and ID. The columns 9 and ID are identical in structure and comprise three hollow insulator sections H, I3 and I5 mounted one above the other in the order named and secured together by metallic casings l1 and 19. The hollow insulator sections I I, I3 and [5 are preferably made of porcelain or other weather-proof material.

The upper section I5 of each column houses a circuit interrupting means, as more clearly shown in Fig. 3. Disposed within the insulator I5 is a tube 2| of insulating material secured at its lower end to the upstanding flange 23 of the casing E9 to provide an inner chamber and an annular space 21 between the tubular member 2| and the insulator I5. The chamber 25 and annular space 21 are preferably filled with insulating liquid such as oil. Rising from the socket 29 in the casing I9 is a perforated metallic support sleeve 3| which carries a tubular insulator 33. Mounted on top of the insulating sleeve 33 are a plurality of washers 35 and 31 of insulating material and of different internal diameter but of substantially the same external diameter. The washers 35 and 31 provide a plurality of small chambers 39 communicating with each other through the openings 4| in the washers 35. Disposed on top of the uppermost washer 31 is a metallic washer 42 of substantially the same form as the washers 35, except that it has downwardly extending arms 44 secured to the outer side thereof. Carried by the metallic washer 42 are a plurality of cylindrical sections 43 of insulating material having ribs 45 at least on the inner surface thereof, the purpose of which will be explained more fully hereinafter.

Mounted upon the cylindrical sections 43 is a cup-shaped shell 41 of insulating material having a metallic liner 49 secured to the inside thereof. The cup-shaped member 41 is provided with three outwardly extending projections 5|, only one of which is shown in Fig. 3 for slidably receiving the reduced end portion 53 of a corresponding number of support rods 55. The support rods 55 are of insulating material and extend downwardly the entire length of the stack of insulating members composed of the sections 43 and the washers 35 and 31, respectively. The lower ends of the support rods 55 are secured to a perforated plate 51 carried by the casing I9. It will thus be noted that the support rods 55 maintain the washers 35 and 31, the metallic washer 42, and the sections 43 in alignment.

The metallic liner 49 has an inwardly extending flange 59 which carries a plurality of springs 0|, the upper ends of which bear against a pressure plate 63 carried by the lower end of a perforated metallic sleeve 65. the metallic sleeve 65 is secured to a metallic cap member 61 mounted upon the end of the tubular member 2|. It will thus be seen that the springs 6| maintain the washers 35, 31 and 42 as well as the sections 43 of insulating material in compression. It is also apparent that upon the rise of the pressure above a predetermined value in the passages 4|, the column of washers are permitted to expand to relieve the pressure.

The bearing plate 63 also carries a stationary contact 59 of the tulip type which makes electrical connection with an upstanding conductor 1| extending through the perforated metallic sleeve 55 and a relatively large opening 13 in the cap member 61. The upper end of the conductor 1| has a section of reduced diameter and carries a closure cap 15, preferably of insulating material such as porcelain. The upper end of the conductor 1| also extends beyond the porcelain cap 15 and serves as a terminal to which one of the line connections for the breaker may be made.

Within the perforated supporting sleeve 3| of the metallic casing I9 are mounted a plurality The upper end of of contact fingers 11 which are electrically connected to the casing I9. Operable through the lower wall 19 of the casing I9 is a movable contact rod 8| which makes sliding contacting engagement with the contact fingers 11 and is adapted to be operable through the aligned apertures 4| in the washers 35 as well as through the tubular sections 43 and into and out of engagement with the stationary tulip contact 89. Surrounding the tubular member 2| is an annular support member 83 having an annular channel or groove 85 in which a pair of spaced concentric tubes 81 and 89 are carried. The tubes 81 and 89 form an annular container 9| which is preferably filled with liquid of a partially conducting type such as water.

The upper ends of the insulator section I5 and the tubular members 81, 89 and 2| are joined by a metallic conically shaped ring 93 having perforations 95 therein directly above the annular container 9|. The annular cap member 93 thus holds the respective tubular members and casing rigidly together and also seals the annular spaces on either side of the annular container 9|. The cap member 93 is also provided with electrodes 91 which extend downwardly through the apertures 95 and are partially submerged in the liquid contained in the container 9|. An electrical connection, for a purpose to appear hereinafter, is made from the support member 83 to the contact arm 44 of the metallic washer 42 through a flexible shunt 94 and a spring pressed contact pin 98 as shown.

When the contact rod 8| is in the closed circuit position, that is, when its upper end makes engagement with the stationary contact 09, a circuit is established through the interrupter from the conductor 1|, stationary contact 69, contact rod 8|, contact fingers 11 to the casing I9. The casing I9 has a laterally projecting stud 99 to which is connected a tubular conductor I0| for connecting the two circuit interrupting structures contained, respectively, in the sections I5 of the columns 9 and I0 in series. The circuit for the complete single phase unit thus proceeds from the casing I9, to the stud 99, to the connecting tubular conductor IOI to a similar interrupting structure housed in the adjacent column and terminates at the upper line terminal thereof.

The contact rod 8| is preferably actuated to open and closed circuit positions by a hydraulic operating mechanism carried within the sections II and I3 of each of the columns 9 and I0 as more clearly shown in Fig. 4. The lower end of the contact rod 8| is provided with a piston I03 which is slida-bly operative in a cylinder I05 supported at its upper end to the metallic casing I9. The lower end of the cylinder I05 is joined with a liquid conducting pipe I01 of insulating material having a sealed connection at its lower end with the upper half of the casing I1. Paralleling the cylinder I05 and the pipe I01 is a second pipe I09 of insulating material for the conduction of operating liquid to the upper end of the cylinder I05. The pipe I09 is sealed at its upper end to the casing I9 and communicates with the cylinder I05 through a chamber I I contained' in the casing I9 whereas the lower end of the pipe I09 is sealed to the upper portion of the metallic casing I1.

The liquid conducting pipes I01 and I09 are joined at their lower ends by pipes H3 and. H5, respectively, and extend through the insulator section II. The pipes H3 and 5 have their upper ends sealed to the lower portion of the casing I1 and are sealed at their lower ends to a casing member II1 mounted upon the base 1. The liquid conducting pipes I01 and I99 are surrounded by a tubular support member I Hi, whereas the conducting pipes I I 3 and I I 5 are surrounded by a similar support member I2I. The tubular support members H9 and I2I are sealed at their respective ends to the casings 89, I1 and I I1 to provide separate cylindrical chambers'I23 and I25 and annular chambers I21 and I29 within the insulating sections 3 and Il, respectively.

The chambers I23 and I25 are preferably filled with insulating liquid such as oil. The annular chambers I21 and IE9 are preferably only partially filled with insulating liquid, as shown, or it is also feasible to dispense with insulating liquid within these annular chambers andrely entirely upon air as an insulating medium. In the event that partial liquid insulation is desired so asto provide a short column of liquid adjacent the metallic casings I9, I1 and H1, suitable partition members of insulating material, preferably a molded material, as shown at I31 and I33, are employed. The partition members I3! and. I33 are constructed in the form of a pair of annular discs having opposed beveled edges at the inner and outer circumferences thereof. The beveled edges at the outer circumference project on either side of an internally extending flange I95 formed integrally with each of the insulator sections II and I3. An annular gasket I31 of suitable material is disposed between the beveled edges at the inner circumference of the partition members HI and I33 and a similar gasket I39 is disposed between each beveled edge and the inwardly extending flange I35 at the outer circumference of the partition members. A bolt MI, preferably of insulating material, clamps the two partition members together, thereby causing the gaskets I31 and I39 to make sealing engagement with the insulating sections II and I3 and the inner tubular members I2I and H9, respectively. Thus the partition members I35, I 33 form an eiTective seal to permit a short column of insulating liquid in the annular spaces I21 and I29 immediately below the metallic casing members I9 and I1. These relatively short columns of liquid insulation greatly increase the resistance to internal breakdown within the sections II and I3 without the necessity of completely filling the annular spaces I 21 and i251 with insulating liquid.

The lower ends of the liquid conducting pipes H3 and H5 extend through the upper wall of the base 1 and are, respectively, connected as shown in Fig. 5 by pipes I93 and M5 to an operating cylinder M1 disposed in the base I, preferably adjacent each column 9 and I9. Each of the operating cylinders I41 has a piston M29 which is coupled. to an actuating lever l5l, The two actuating levers I55 of each phase are interconnected by a tie rod I53 so as to cause the two pistons to be operated in unison. As more particularly shown in Fig. 5, the right-hand end of each tie rod I 53 has connected thereto an operating spring I55 which biases the operating levers I5I in a clockwise direction, and when permitted to move in that direction, causes the pistons M9 to expel operating liquid from the cylinders M1 into the pipes I95, H5, 569, the chamber ill, the operating cylinder I95 and against the upper side of the contact rod piston i623 so to move the contact rod 8! downwardly out of engagement with the stationary contact 59 tothe open circuit position as shown in Fig. 3.

As shown in Fig. 5, the right-hand operating levers I5I are of bell crank form and are mechanically interconnected by a transversely extending tie rod I51. Thus the respective pistons I49 in all three phases of the operating mechanism are caused to be operated simultaneously irrespective of any inequality in the force applied by the operating springs I55,

The respective contact rods 8I are caused to be moved to the closed circuit position by a compresed air actuated piston I59 housed withing each base member 1 and mechanically coupled to the right-hand operating lever I5I. Each of the pistons I59 is adapted to operate in a cylinder I6I having air lines I63 connected thereto which are fed from a common source of supply not shown. Control of the air supply for closing the'interrupter may be had by a valve I65 electrically operated by the solenoid I61. Thus, the closing operation of the three-phase interrupter is accomplished by opening of the control valve I65 which causes compressed air to be led through the air lines I63 to the individual operating cylinders I5I which, in turn, causes the pistons I59 of each phase to actuate the operating levers I5I in a counter-clockwise direction against the bias of the springs I55, causing the pistons I49 to drive operating liquid through the pipes I43, II3, I91 into the cylinder I95 against the lower side of the contact rod piston I03.

The contact rods 8I are held in closed circuit position against the biasing action of the springs I55 by a latch member I69, in this instance engaging the bell crank operating arm I5I. The latch member I69 is released so as to initiate an opening operation by a solenoid trip coil mechanism I1l shown. From the foregoing description of the operating mechanism, it is apparent that a more uniform movement is obtained, both during the opening and closing operation in that separate actuating means are used for each phase of the three-phase breaker. However, simultaneous operation is obtained for all the phases in that each operating mechanism is mechanically interconnected by the transverse tie rod I51. In order to prevent exposure to any of the operating parts, the tie rod I51 is preferably enclosed within the tubular sections I13 joining the three base members 1 to each other. The tubular sections I 13 also serve as a convenient housing for the transverse air lines I63 leading to the respective air cylinders I6I.

The hydraulic operating mechanism above de scribed is particularly adapted for high voltage circuit breakers in that by the use of oil as the force, transmitting liquid, greater insulation to ground is secured. The operating mechanism is also admirably suited for obtaining ultra-high speed contact operation. The specific mechanism described .has made contact speeds up to from 32 to 50 feet per second possible, thereby greatly facilitating the high speed clearing of faults which is essential in the maintenance of system stability.

During the opening operation of the interrupter during conditions of load or overload, extinction of the arc and circuit interruption are obtained as follows: Energization of the trip coil I1I releases the latch I59, causing the operating springs I55 to actuate the pistons I49 to cause operating liquid to flow in the manner previously described. As a consequence of the liquid flow the contact rods 8I in their respective columns are actuated to the open circuit position, causing an arc to be drawn between the contact rod 8| and the stationary contact 59. This arc is drawn through the relatively unrestricted chamber formed by the tubular sections 43 of insulating material. As the contact rod 8| moves downwardly the arc is drawn into the aperture of the metallic Washer 42 which forms an intermediate contact terminal. The distance between the stationary contact 69 and the intermediate contact 42 is preferably substantially equal to the minimum arc extinction distance, that is, the contact distance which is at least necessary for an interruption of the circuit, or in other words, the minimum distance necessary to avoid reignition of the arc. The openings within the sections 43 of insulating material are such that the arc playing therein is subjected to substantially no arc-extinguishing influence, thereby permitting the arc to play therein substantially unrestricted. This arrangement is particularly advantageous in that its avoids a sudden rise in arc voltage and maintains the arc voltage at a low value until at least the minimum arc-extinction distance has been obtained. An extremely low arc energy device thereby results.

As the contact rod 8! continues its down- Ward movement past the intermediate contact 42, the arc transfers to the intermediate contact. Another section of the arc is then drawn from the intermediate contact 42 into the chambers 39 and communicating passages 4| formed by the washers 35 and 37. The communicating openings 4] in the washers 35 are preferably of a diameter only slightly larger than the contact rod 8|, thereby causing the are drawn therein to be materially restricted in cross section. The material restriction of the arc as it is being lengthened at an extremely rapid rate in conjunction With the effect of the products of decomposition of extinguishing liquid upon the arc exerts a high arc-extinguishing influence and causes the arc to be extinguished. However,

prior to extinction of the arc between the intermediate contact 42 and the moving contact rod 8|, the section of are between the stationary contact 69, and the intermediate contact 42 is extinguished by virtue of the parallel path shunting this section of arc. As soon as the arc is established between the stationary contact 69 and the intermediate contact 42, current will fiow from the stationary contact 69 through the perforated support sleeve 65, the cap member 87, the electrodes 91, partially conducting liquid 9!, the annular support 83, the flexible shunt 94, the movable contact pin 96, and the projection 44, to the intermediate contact 42. Inasmuch as the voltage drop in shunt with this section of the arc is less than that required to maintain the arc, the arc between the stationary contact 69 and the intermediate contact 42 will be extinguished. Upon the establishment of the circuit through the liquid resistance path as above outlined, the section of are drawn below the intermediate contact 42 in the passages 4! will be placed in series with the liquid resistance 9!. The liquid resistance 9| is particularly beneficial in assisting arc extinction during the interruption of arcs of low current value.

During the interruption of the arc drawn in the sections 43 of insulating material as well as in the passages 4|, considerable quantities of arc gases are generated, raising the pressure within the passages so as to cause either the sections 43 or the washers 35, 31 to separate, permitting the gas to escape laterally between the washers or sections and rise upwardly to the surface of the insulating liquid in the chamber 25. The action of the arc gases upon the liquid in the chamber 25 causes a circulation of arc-extinguishing liquid upwardly past the insulating shell 41. As the insulating liquid mixed with the arc gases streams past the insulating shell 41 the spirally disposed ribs 48 on the shell (Fig. 6) cause the combined liquid and gas to rotate and consequently, the liquid and gas are quickly separated by centrifugal action. Thus the space surrounding the stationary contact 69 is quickly devoided of arc gases and restored to a high dielectric strength. The are gases emerge from the upper surface in the liquid of the chamber 25 through the perforations in the support sleeve 65 through the aperture 13 in the cap member 61 and escape from the housing through the annular space provided between the insulating cap 15 and the conical metal cap 93. Vapor rising from the liquid 9! escapes upwardly through the apertures 95 and is deflected downwardly and out through the same annular venting space by a metallic barrier extension H5 carried by the cap member Bl. Thus the barrier I15 prevents intermingling of the vapors emerging from the arc-extinguishing chamber and from the liquid resistance. It is also apparent that any condensates from the re spective vapors will be carried to the exterior of the housing and will not intermingle with the respective liquids contained within the housing.

Upon extinction of the arc and interruption of the circuit, voltage breakdown between the stationary contact 59 and the moving contact rod 8| is prevented in part by a uniform distribution of the electrostatic lines of force emanating from the stationary contact 69 by means of the metallic lining member 49 surrounding the stationary contact. The insulating shell 41 in contact with the liner member 49 also avoids any needle effect which may cause a voltage breakdown. Voltage breakdown along the insulating arcextinguishing structure is further decreased by the provision of ribs 45 in the sections 43 of insulating material which greatly increases the creepage distance. The washers 35 and 31 being of different internal diameter also present a corrugated surface which greatly increases the creepage distance and consequently lessens the danger of internal breakdown due to high electrical stresses. Further precautions have been taken in order to provide a more uniform electrostatic field between the breaker terminals when the breaker is in the open position by the provision of a curved flange IT! at the lower side of the annular support member 83 and a similar curved flange I19 extending from the flange 23 of the casing 19.

In order to preserve the insulating qualities of the arc-extinguishing liquid of the chamber 25, the casing I9 is provided with a chamber |8l communicating with the chamber 25 and also the arc chamber formed by the passages 4|. The chamber l8l serves as a sump for collecting metallic particles resulting from action of the are upon the contact structure as well as action of the arc upon the insulating liquid. The metallic particles thus formed are collected in the sump l8! and maintained in a neutral electrostatic field, that is, at the same electrical potential to which the casing I9 is subjected and thereby greatly reduces insulation failure of the arcextinguishing liquid within the chamber 25. The

external insulation of each interrupter column has also been increased by mounting the stationary contact 69 a substantial distance below the upper end of the insulator section l5.

The structural features of the interrupter as above described provide adequate insulation and circuit interrupting ability to successfully interrupt a circuit of from 400 to 600 k. v. connected across the two interrupter columns, or from 200 to 300 k. v. across one interrupter column, within a very short interval of time. Furthermore, the structure possesses sufiicient insulation when in the open circuit position to completely isolate two connected circuits without the use of additional air disconnect switches externally of the interrupter.

Although we have shown and described a specific circuit interrupting structure, it is to be understood that the same was for the purpose of illustration and that changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the appended claims.

We claim as our invention:

1. In a circuit interrupter, separable contact means for establishing an arc, arc extinguishing means comprising means of insulating material defining an elongated arc passage in which said are is drawn, said are passage having a portion thereof of length substantially corresponding to the least arc extension distance and such as to subject the arc to substantially no arc extinguishing influence, said are passage having another portion thereof adapted to subject the arc to an arc extinguishing influence.

2. In a circuit interrupter, a plurality of insulating members having openings therethrough and arranged in contiguous relation to form a continuous passage, operable contact means for drawing an are along said passage, a plurality of said insulating members having openings of cross section to enable the arc to play therein substantially unrestricted, a second plurality of said insulating members having openings of cross section to materially restrict the cross section of the are for assisting arc extinction, said separable contact means being arranged to establish the arc first in the portion of the arc passage having the greater cross-section and thereafter to establish the arc in the more restricted portion of the arc passage, said arc passage of greater cross section having a length substantially corresponding to the least are extinction distance.

3. In a circuit interrupter, arc extinguishing means comprising a plurality of chambers of insulating material disposed one on top of the other and having aligned communicating openings therebetween of relatively small cross-sec tion, an additional chamber of insulating material on top of said plurality of chambers and having a cross-section substantially greater than the cross-section of said openings and a length corresponding substantially to the minimum arc extension distance, a stationary contact adjacent the upper end of said additional chamber, and a movable contact coacting with said stationary contact and adapted to be moved through said chambers to establish an arc therein, the cross section of said additional chamber enabling the arc to play therein substantially unrestricted whereas the cross section of said communicating openings are small enough to subject the arc to a substantial arc extinguishing influence.

4. In a circuit interrupter, means of insulating material defining an elongated arc passage, a

stationary contact adjacent one endof said are passage, a substantial portion of said are passage adjacent said stationary contact having a length substantially equal to the minimum arc extinction distance and a cross-sectional area large enough to enable an arc to play therein substantially unrestricted, the remaining portion of said arc passage having a smaller cross-sectional area to subject the arc to an arc extinguishing influonce, an arc terminal member disposed between said portions of the arc passage, a coacting contact member movable through said are passage to sequentially establish arcs in said portions of the arc passage, and an impedance connected between said stationary contact and said arc terminal member for by-passing the arc current in the first drawn arc to cause its extinction and for-assisting extinction of the second drawn arc.

5. In a circuit interrupter, a stationary contact, an arc terminal member positioned from said stationary contact a distance corresponding substantially to the minimum arc extinction distance, a coacting contact member movable to first establish an are between said stationary contact and said are terminal member and then extend the arc beyond said are terminal member, and are extinguishing means comprising means of insulating material defining a constricted arc path along which said extended portion of the arc is drawn for extinguishing the arc,

6. In a circuit interrupter, a stationary contact, an arc terminal member positioned from said stationary contact a distance corresponding substantially to the minimum arc extinction distance, a coacting contact member movable to first establish an arc between said stationary contact and said are terminal member and then extend the arc beyond said are terminal member, and a resistance connected between said stationary contact and said are terminal member to bypass the arc current in the first drawn arc and assist in extinguishing the arc.

7. In a circuit interrupter, a tubular member of insulating material, circuit interrupting means within said tubular member including a pair of spaced contact members and a coacting contact movable to establish an are between said contact members and to extend the are beyond one of said contact members, an annular body of partially conducting liquid surrounding said tubular member, electrodes contacting the opposite ends of said body of liquid, and means respectively connecting said electrodes to said spaced contact members to provide a liquid resistance path in parallel with the are path between said contact members.

8. In a circuit interrupter, a vertically disposed tubular member of insulating material closed at the lower end, a body of arc extinguishing liquid in said tubular member, contact means immersed in said are extinguishing liquid including a pair of spaced contact members and a coacting contact movable to establish an are at least between said spaced contact members, an annular enclosure surrounding said tubular member, partially conducting liquid in said annular enclosure, spaced electrodes having contacting engagement with said partially conducting liquid and connected respectively, to said spaced contact members to provide a liquid resistance path in parallel therewith, and separate vent paths adjacent the upper ends of said tubular member and said annular enclosure for the discharge of gases resulting from the respective liquids.

9. In a circuit interrupter, a vertically disposed hollow column of insulating material, a tubular member of insulating material within said column, a casing member closing the lower ends of said column and tubular member, insulating liquid in said tubular member and in the annular space between said tubular member and said column, contact means immersed in said liquid in said tubular member including a pair of spaced contacts and means for establishing an arc therebetween, a liquid container at least partially of insulating material in the annular space surrounding said tubular member, partially conducting liquid in said container, spaced electrodes in said partially conducting liquid and connected respectively, to said spaced contacts to provide a resistance path in parallel therewith, means including said liquid container for sealing the upper end of said annular space between said column and said tubular member, a cap member disposed in spaced relation over said column to provide an escape passage for gases resulting from vaporization of said partially conducting liquid and the insulating liquid in said tubular member, and baffle means for directing condensates of said respective gases exteriorly of said column through said escape passage.

10, In a high voltage circuit breaker, a vertically mounted tubular member of insulating material, a closure for the lower end of said tubular member, a body of arc extinguishing liquid in said tubular member, a second body of are extinguishing liquid in said tubular member, a stationary contact in said second body of are extinguishing liquid, a coacting contact member movable to establish an arc in said second body of arc extinguishing liquid, and an electrostatic stress distributing member in surrounding spaced relation with respect to said stationary contact, said stress distributing member being disposed in the path of movement of said first are extinguishing liquid set in motion by gas pressure resulting from action of the are upon said second body of arc extinguishing liquid.

11. In a high voltage circuit breaker, a vertically mounted tubular member of insulating l,,

material, a closure for the lower end of said tubular member, a body of arc extinguishing liquid in said tubular member, a second body of arc extinguishing liquid in said tubular member, a stationary contact in said second body of arc extinguishing liquid, a coacting contact member movable to establish an arc in said second body of arc extinguishing liquid, and a metallic cup-shaped member disposed in surrounding spaced relation with respect to said stationary :7

contact for uniformly distributing the electrostatic lines of force in the region of said contact, said cup-shaped member having a maximum diameter slightly less than the inside diameter of said tubular member to provide a high velocity flow of said first arc extinguishing liquid past said cup-shaped member in response to gas pressure resulting from formation of the arc.

12. In a high voltage circuit breaker, a vertically mounted tubular member of insulating material, a closure for the lower end of said tubular member, a body of arc extinguishing liquid in said tubular member, a second body of arc extinguishing liquid in said tubular member. a stationary contact in said second body of are extinguishing liquid, a coacting contact member movable to establish an arc in said second body of arc extinguishing liquid, and a metallic cup-shaped member disposed in surrounding spaced relation with respect to said stationary contact for uniformly distributing the electrostatic lines of force in the region of said contact, and a supporting shell of insulating material on the outside of said metallic cup-shaped member, said shell of insulating material having outwardly projecting ribs of spiral form thereon to cause that portion of said first body of arc extinguishing liquid set in motion by gas pressure resulting from arcing in said second body of are extinguishing liquid to assume a rotary motion whereby the arc gases and liquid are quickly separated by centrifugal action.

13. In a circuit interrupter, separable contact means for establishing an arc, arc extinguishing means comprising means of insulating material defining an elongated arc passage in which said are is drawn, said are passage having a portion thereof of length substantially corresponding to the least are extinction distance and such as to subject the arc to substantially no arc extinguishing influence, said are passage having another portion thereof adapted to subject the arc to an arc extinguishing influence, and operating means for separating said contact means, arranged to elongate said are at an average velocity of at least 32 feet per second during the circuit opening operation.

14. In a circuit interrupter, a stationary contact, an arc terminal member positioned from said stationary contact a distance corresponding substantially to the minimum arc extinction distance, a coacting contact member movable to first establish an are between said stationary contact and said are terminal member and then extend the are beyond said are terminal member, are extinguishing means comprising means of insulating material defining a constricted arc path along which said extended portion of the arc is drawn for extinguishing the arc, and operating means for said coacting contact member capable of high speed movement to cause said are to be elongated at an average speed of at least 32 feet per second.

15. In a circuit interrupter, means of insulating material defining an elongated arc passage, a stationary contact adjacent one end of said are passage, a substantial portion of said are passage adjacent said stationary contact having a length substantially equal to the minimum arc extinction distance and a cross-sectional area large enough to enable an arc to play therein substantially unrestricted, the remaining portion of said are passag having a smaller cross-sectional area to subject the arc to an arc extinguishing influence, an arc terminal member disposed between said portions of the arc passage, a coacting contact member movable through said are passage to sequentially establish arcs in said portions of the arc passage, operating means for moving said coacting contact member at high speed to elongate said arcs at an average speed of at least 32 feet per second.

PAUL DUFFING. JOSEPH BEl-IRINGER.

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