US2252983A

US2252983A - Electric circuit breaker

Info

Publication number: US2252983A
Application number: US189615A
Authority: US
Inventors: Allen M Rossman
Original assignee: Individual
Current assignee: Individual
Priority date: 1938-02-09
Filing date: 1938-02-09
Publication date: 1941-08-19
Anticipated expiration: 1958-08-19

Description

Aug. 1941- A. M. RossMAN 2,252,983

ELECTRIC CIRCUIT BREAKER Filed Feb. 9, 1938 GSheets-Sheet 1 IN VENTOR.

Fig

m m m s T s T o A E M n M A Y B Aug. 19, 1941.- A. M. ROSSMAN ELECTRIC CIRCUIT BREAKER e Sheets-Sheet 2 Filed Feb. 9, 1938 INVENTOR. OSS/WUU A//en M Q BY ATTORNE g 1941- A. M. ROSSMAN ELECTRIC CIRCUIT BREAKER Filed Feb. 9, 1938 6 Sheets-Sheet 5 INVENTOR. A//e/7 M. 2055mm? BY ATTORNEY.

Aug. 19, 1941- A. M. ROSSMAN ELECTRIC CIRCUIT BREAKER s Sheets-Sheet 4 Filed Feb. 9, 1938 .U R Y Wm m we" m M M W T9 4 H W B .0. M 2 F Aug. 19, 1941. A. M. ROSSMAN ELECTRIC CIRCUIT BREAKER Filed Feb. 9, 1958 6 Sheets-Sheet 5 INVENTOR. A/len M. Eossman' BY ATTORNEY.

Patented Aug. 19, 1941 UNITED STATES PATENT OFFICE ELECTRIC CIRCUIT BREAKER Allen M. Rossman, Wilmette, Ill.

Application February 9, 1938, Serial No. 189,615

24 Claims.

- terrupted in a bath of insulating liquid, such as oil for example.

'In interrupting an electric-circuit, particularly one of high kilovoltampere capacity, in oil, the resulting arc produces a gas bubble, and follows a path of ionized gas through the bubble. In an alternating current circuit, both the cur rent the voltage across the gap and through the bubble pass through a zero value and reverse their direction twice during each cycle. The are will be reestablished after each current reversal provided the resistance of the gap to breakdown is sufficiently low to permit the voltage to establish. a path of ionized gas through the gap. Ultimate extinguishment of the are results when the resistance of the gap to breakdown'is sufficiently high-to prevent the establishment of a path of ionized gas through the gap. This: latter condition results when the separation of the terminals is sufiic'iently great to prevent the reestablishment of. a path of ionized gases either through a medium which is composed exclusively of gas or through a medium which is composed partly of gas and partly of liquid. As the voltage required: to break down a given thickness of liquid such as oil, is many times. that required to break down the same thickness. of' gas, it follows that the interposition of a layer of liquid between the twoterminals greatly increases the resistance to breakdown of the path between them and for a given peak value of voltage between terminals, requires a less separation of the contacts to prevent the reestablishment of the are after it has been broken. Furthermore, the cooling effect of the body of oil around the arc bubble acts to deionize the same. In those. circuit breakers wherein the arrangement is such that the magnetic forces produced by the current flow urge the arc towards the wall of the bubble, the cooling action and the consequent deionization is facilitated because the are through the gas bubble is forced into the region of the bubble wall thus accelerating. the cooling action at the place where the ionization is the greatest. Circuit breakers relying primarily upon the. lengthother are in series therewith.

the circuit interrupting arc.

ening of the arc gap and the magnetic blowing of the current path through the bubble towards the wall of the bubble have been relatively successful for low and medium KVA capacity breakers. However, with breakers of high KVA- capacity other means are desirable to prevent the reestablishment of a broken are. One known type of circuit. breaker provides means whereby cool oil is blown through one of the arc paths, the pressure for blowing that oil through the arc path being developed by the It is with this type of circuit breaker that the present invention is primarily concerned.

In a circuit breaker of the above type one of the arcs may be termed the circuit interrupt.- ing are and the other may be termed the pressure developing arc. Oil is caused to flow under pressure created by the pressure developing arc into the path of the other arc. However, the circuit interrupting are also develops a pressure and therefore, in the prior constructions, the

pressure developing arc had to develop sufficient pressure to force oil through the circuit interrupting are against the pressure developed by It is one of the objects of the present invention to provide a simple circuit breaker structure of the above mentioned character wherein the arrangement is such that the circuit interrupting are develops a comparatively small pressure in a direction resisting the flow of insulating liquid set up by the other arc. This is accomplished by providing an arrangement such that the flow of oil in the region of the circuit interruptingarc under the pressure developed by the other are moves the arc bubble in the same direction as the arc bubble of the circuit interrupting arc would move if the pressure developing arc were absent. By this arrangement the resulting motion of the arc bubble at the circuit interrupting arc is under the cumulative action of the buoyancy of the arc bubble,and the force of pressure developed by the pressure developing arc.

It is a further object of the present invention to provide a circuit breaker of the above type wherein the circuit interrupting arc is in a loop circuit so that resulting magnetic action tends to sweep the are towards the wall of the gas bubble and wherein the buoyancy of the gas bubble and the force of the oil blast are both in the same direction so that all three forces act simultaneously to inhibit arc reformation after the current through the arc has passed through a zero value.

It is a still further object of the present invention to provide a circuit interrupter of the above character wherein the buoyancy of the arc bubble is utilized and at the same time there is substantially no action of the arc bubble to push the oil blast out of its path of maximum utility. By this arrangement practically all of the oil of the oil blast is utilized for displacing and cooling the arc gas bubble, the arc gas bubble assisting or at least not substantially interfering with the freedom of movement of the oil under the action of the pressure developing arc.

It is another object of the present invention to provide a circuit breaker wherein the entire mass of oil that is set into motion by the pressure developing arc can be utilized for effecting a movement of oil through or around the circuit interrupting arc.

In accordance with one of the principles of the present invention substantially the entire bulk of the body of insulating liquid of the tank is between the pairs of contacts that are being separated. One of the sets of contacts produces an arc in a pressure developing chamber that is substantially devoid of gas or other compressible media so that the pressure developed by the arc therein can expel a maximum amount of oil from that chamber into an arc extinguishing chamber. All of the oil thus expelled pushes the great mass of the body of oil of the tank ahead of it so that a like quantity passes from the pressure developing chamber into the other chamber and into the path of the other are. terrupting arc is entirely outside of the pressure chamber so that none of the oil in the pressure chamber is dissipated by the other arc for non-blast producing purposes.

It is a further object of the present invention to produce an oil circuit breaker of the above mentioned character which will be simple in construction and reliable in its action and which will be economical of manufacture.

It is another object of this invention to provide an arrangement whereby certain types of non-oil-blast circuit breakers may be converted into oil blast breakers with a minimum of change in the breaker arrangement and at a minimum of cost.

It is a still further object of the present invention to provide an improved retarding mechanism for decelerating the movement of the contact making members as the same approach the switch open position without interfering with the initial switch opening movement, thus allowing a high speed initial opening movement with a cushioned stop at the end of the opening operation.

The attainment of the above and further objects of the present invention will be apparent from the following specification taken in conjunction with the accompanying drawings forming a part thereof.

In the drawings:

Figure 1 is a longitudinal sectional view through a circuit breaker embodying the present invention, said view being taken along the line ll of Figure 2;

Figure 2 is a transverse cross sectional view of the circuit breaker of Figure 1, said view being taken along the line 2-2 of Figure 1;

Figure 3 is a sectional view taken along the line 3-3 of Figure 1;

Figure 4 is a view at right angles to Figure 1, said. view being taken along the line 44 of Fig- The circuit inure 2, and showing the switch in its open position;

Figure 5 is a fragmentary View of a part 01' Figure 1, and illustrating the switch in its open position;

Figure 6 is a sectional view taken along the line 6--6 of Figure '7;

Figure 7 is a diagrammatic view of another circuit breaker, illustrating another embodiment of the present invention;

Figures 8 and 9 are views corresponding to Figures 6 and 7 and illustrating another embodiment of the present invention, Figure 8 being a section taken along the line 88 of Figure 9;

Figures 10, 11, 12, 13, 15 and 17 are diagrammatic views illustrating other embodiments of the present invention;

Figure 14 is a sectional View taken along the line M-M of Figure 15;

Figure 16 is a sectional view taken along the line |6l5 of Figure 17;

Figure 18 is a longitudinal sectional view through a single phase high voltage circuit breaker embodying the present invention;

Figure 19 is an enlarged longitudinal sectional view of one of the contact structures and pressure chambers of the circuit breaker of Figure 18; and

Figures 20 and 21 are views corresponding to Figure 19 and illustrating different positions of the contact making structure.

Similar reference numerals throughout the various figures of drawings indicate similar parts.

Reference may now be had more particularly to the circuit breaker illustrated in Figures 1 to 4 inclusive. The circuit breaker is indicated in general by the reference numeral I, and includes a dome or head 2 from which is suspended the usual tank 3 in the usual manner, the tank 3 forming a fluid tight fit with the head. The circuit breaker here illustrated is a three phase circuit breaker. The top of the head or dome has three pairs of insulating bushing openings through which insulating bushings 6a, 6b and 8c, and la, lb and 7c extend, the bushings being held in place by the usual collars 9 bolted or otherwise suitably secured to the top of the circuit breaker. Through each insulating bushing extends a conductor II that terminates at its bottom in a switch contact, indicated at [2 and I2 in Figure 1. The bottom of the circuit breaker head is provided with a horizontally extending base plate l3 forming an integral part of the head and which base plate is provided with a large opening 14 at one side thereof to permit free communication between the space on the inside of the circuit breaker head and the circuit breaker tank. At its side the circuit breaker head 2 has an opening 15 through which extend the operating links and levers for operating the circuit breaker. A closure Hi closes the opening l5 and provides bearings for a rotary operating shaft I! that is oscillated by a link or crank l8 on the outside circuit breaker head to oscillate the shaft and, through the links and levers within the head 2, to cause movement of the circuit breaker contact making member, to be presently described.

Within the tank 3 there is provided the usual cylindrical insulating liner 20 which forms a substantial sealing fit with the top of the tank 3, by means of a ring gasket or the like 2|.

Means is provided on the interior of the circuit breaker tank for dividing the circuit breaker into two separate communicating chambers.

This. means. comprises a verticallyfextending: centrally located barrier '22 ,1 of i wood? orother suitable insulating material, whichextends across the: tank making. a sealing fit with the liner: and projecting downwardly a' substantial distancefrom the base. plate l3.. Vertical insulating partitions 23; '24, 25 and: 26 extend. from the central barrier 22 to the liner. 2.0.. between adjacent phases and act as barriers to preclude all possibilities of arc-over between adjacent phases, as is apparent" from Figure. 3. Atithe top of the partitions 23-24 there is provided an arcuate wooden spacer 21 that extends from the insulating liner 20' to the central barrier 22. At the bottom ofthepartitions 25-26 there isan arcuate wooden partition 28 having three oversized openings 29, one for each. phase: The compartments formed by the partitions. 2526 communicate. at the top with rthcficircuit breaker head through the opening [4, and communicate at their bottom with the interior of the circuit breaker tank throughthe openings'29'.

Within the central insulating barrier 22 there are formed three vertically extending circular openings, one for each phase, indicated at 3|, through each of which extends an operating rod and dash pot arrangement to be presently described. In each vertically extending opening there is mounted an insulating tube or liner 32 closed at its bottom by a screw plug 33 having an opening 34 through which an insulating operating rod 35is slidable. vThe operating rod 35 is secured to a piston 35' at its upper end. At the upper end of the tube or liner 32 there is threaded a closure plug 38 which is provided. with a central opening. through which a tube .39 slides with a. sealing fit. The tube 39 is screw threaded tothe top of the piston 35. The piston 36 also has a connecting rod 40 joined thereto about a pivot pin 4!. A spring 42 extends from the bottom of the plug 38 to the piston for accelerating. the initial switch opening movement and reducing the amount of force required to start the opening movement. This spring also cushions theclosing operation. The spring extends into a circular groove 43 in the piston.

The barrier 22 and the tube or liner 32 are each provided with a large opening 44 above the piston and with a large'opening 45 below the H,

piston when the piston is in the position illustrated in Figure 1. The opening 45 is covered by the piston as the piston: approaches its switch open position. A restricted opening 46 is provided in the barrier 22' and tube or liner 32' below the lowermost limit of travel of the piston 35-.

The central barrier plate. 22 with the

vertical partitions

23, 24, 25 and 26", and the cover plate 21 and partition 28 are secured together as an assembly and then bolted or otherwise rigidly secured to the base plate I3 of the circuit breaker head so that thereafter this assembly constitutes a part of the circuit breaker head.

The switch operating rod 35 supports and operates a bridging member which is adapted to be moved into and out of bridging relationship to the contacts l2-l2 of the same phase. The contact making structure comprises two groups of U-shaped wires 50 and5l (Fig. 4) the wires c of each group being nested together, as indicated in Figure 1. The group of nested. wires are secured.- together in spaced relationship by tubular spacers 52, inner and outer clamping. plates 53,. andth-rough bolts 54 extending through the clamping: plates 53andthe spacentubes 52, as illustrated: in. Figure 4'. The bight portions of the U-shaped groups of wires are secured together in spaced relationship at their center by blocks 55, that receive the insulating operating rod 35 between them, and rectangular clamping plates 51 on the outside of the nested groups of wires 505-| Four through bolts 58 extend through the rectangular clamping plates and the blocks 56 to secure the assembly together. The U-chaped wires are free of one another above the clamping plates 53 so that the arm of each wire is freely flexible independently of the other arms. Each U-shaped wire comprises, preferably, a jacket of copper or the like and a core of material having, preferably, a higher elastic'ity than copper, such as ordinary steel. If a non-magnetic core-is desired then the core may be formed of non-magnetic steel alloy, or of bronze or the like. The groups of Wires 50 5l embrace each contact l2.-l'2" on opposite sides thereof, the contact serving to spread. the wires of the two groups slightly and by said spreading action to cause each wirev to exert a spring pressure against the contact. The outermost wire of the U-shaped group of wires is somewhat longer than the others so that all of the arcing will take place at the outermost wire.

Each contact stud I-2--l2' is of a generally triangular shape, as may be seen in Figure 4, so that when the wires ride up on the inclined surfaces 6i), during the switch closing operation, the spreading action of the wires will be gradual and the wires will act as a resilient cushion or spring to reduce any shock that might otherwise be incident to the switch closing operation.

The three. connecting rods 48 of the respective phases are interconnected at their top by a cross bar 63. A clevis 64 is secured to the cross bar 63 between the B and C phase and a similar clevis is similarly secured to the cross bar between the A and B phase. Operating beams are secured to the respective clevises and suitably interconnected, and connected to suitable linkages to a crank 66 on the shaft I! so that oscillation of the shaft [1 causes reciprocation of the connecting rods 40 to move the circuit breaker to its open or closed position. The provision of the pivot joints 4| eliminates the necessity for setting up the tubes 32 of the three phases in perfect alignment.

The circuit breaker is filled with insulating oil to a level above the bottom of the spacer 21 and, preferably, below the top thereof. The space below the spacer 21 is devoid of gas or other compressible media.

An explanation will now be given of the manner of operation of the circuit breaker thus far described. Upon downward movement of the connecting rod 40 the piston 35 causes downward movement of the operating rod 35 and downward movement of the U-shaped contact making members. At this time the top. of the piston is open at 44 to pressure on one side of the circuit breaker and the bottom of the piston is open at 45 to pressure on the opposite side of the circuit breaker. As the connecting. rod continues its downward movement, and. gains speed, the bridging member finally separates from the contacts l2l2' and two arcs are drawn in series for each phase. The expanding gas bubble formed by the are at the contact I2 causes the insulating oil. adjacent thereto to moveupwardly through the opening M. The expanding gas bubble formed at the contact l2 forces oil from the surrounding chamber outwardly through the openings 29. It is to be noted that the current is flowing through the two arcs in opposite directions. As a result the magnetic forces produced by the current flow will cause the two arcs to be bowed outwardly. The are at the contact I2 is thus bowed into the path of oil flowing upwardly through the opening 29. The upwardly moving stream of oil thus serves not only to cool the are bubble but also to force it upwardly, the moving oil assisting the natural buoyancy bubble to force the bubble upwardly and break the ionized path within the arc bubble between the contact and the contact making member. During the switch opening movement the downward motion of the piston 36 forces some of the oil from within the tube 32 outwardly through the

openings

45 and 46 directly into the arc stream thus further facilitating arc extinguishment. After a substantial switch opening movement the skirt of the piston 36 commences to cover the opening 45. As the opening 45 is being covered, the egress of oil from the tube or liner 32 is being progressively restricted so that when the entire opening 45 is covered the only possible avenue of escape of oil from the tube is through the restricted opening 46. This retards further descent of the piston 38 so that the piston and the mechanism moving therewith comes to a gradual stop.

Movable members having one end in the pressure chamber and the other end outside of the pressure chamber present areas which are acted upon by the excess pressure in the pressure chamber during the switch opening operation. The forces thus set up tend to oppose opening of the circuit breaker. In the construction thus far described these forces are balanced by providing counteracting areas on the piston members 36 that are acted upon by the pressure in the pressure chamber. The excess pressure in the pressure chamber exerts a downward thrust on the upper faces of the pistons equivalent to the up ward thrust of those members which have one end in the pressure chamber and the other end in the other chamber, thereby neutralizing the efiect of the upward thrust. If desired the areas at the top of the pistons 36 exposed to the pressure of the pressure chamber may be made larger than is necessary for counterbalancing purposes, whereby the excess thrust due to the pressure in the pressure chamber actually assists the switch opening movement.

Of the two arcs that are drawn in series for each phase, the are at the contact I2 is drawn inside the pressure chamber, and the are at the contact 12 is drawn outside of the pressure chamber. Thi is a distinct advantage over drawing both arcs in the pressure chamber. Only the are at the contact I2 is effective in setting up a movement of oil which is usefully employed in breaking the circuit. The movement of oil set up by the second arc, if it occurs inside the pressure chamber is detrimental. It would tend to build up within the pressure chamber an excess of pressure and tend to expel from the pressure chamber a quantity of oil with no useful effect. It would tend to oppose rather than assist the action of the first are in breaking the circuit. When only one are per phase is drawn inside the pressure chamber, lower pressures are involved and there is less turbulence of the oil in the pressure chamber.

It is to be noted that the insulating bushings 6 of the respective phases are centered in the base plate l3 and spacer 21 by a ring or collar secured to the bushing and which does not make a sealing fit with the base plate and the spacer. There is a small space between the collar and the base plate and between the collar and the spacer 21. As a result, any gases formed by the arc at the contacts I2 are free to ultimately escape from the pressure compartment into the space within the head of the circuit breaker.

To close the circuit breaker the mechanism is operated to raise the connecting rod 40, thus raising the piston 36 and the contact making structure until the contact making wires engage the contacts l2l2'. Thereupon further upward movement of the contacting making structure causes the contacts to ride on the triangular sides 60 of the contacts producing a spreading action of the contact making wires thus causing the wires to exert a spring pressure against the contacts.

It it is desired to inspect the contacts or contact making structure of the circuit breaker above described it is merely necessary to lower the tank 3 together with the liner 2%). When this is done it is apparent that the contacts and the contact making structure is fully exposed to view.

Reference may now be had to the embodiment of the present invention illustrated in Figures 6 and '7. In this embodiment of the invention the circuit breaker is divided into two compartments by a horizontally extending bailie 13 of wood or other suitable insulation which makes a liquidtight substantially sealing fit with the insulating liner 20. Secured to the baffle and projecting upwardly therefrom are three tubes of insulation ll, 12 and 13 in staggered relationship, as illustrated in Figure 6. Each tube of insulation fits snugly into an opening at the bottom of the baffle 10. The bushings la, 61) and To extend through the closed top of the tubes 12, the tubes making a rather loose fit therewith to permit a slow egress of gases or the like from the tubes 12', when gases are generated therein. The contact structure at the bottom of the bushing 61) is within the tube 12, the tube being provided with inspection openings 14 closed by the short slidable tube 75 that may be slid upwardly on the tube 12 to uncover the opening (4 and expose the contact making structure for inspection. The contact making structure for each phase comprises two groups of U-shaped wires with the wires of each group nested together and adapted to embrace the opposite sides of the contact, in the manner illustrated in the switch previously described. Since the bridging members and the manner of making and interrupting the circuit for each of the three phases are alike, a description of the action on one phase will be suflicient. The arm 18 of the bridging member extends into the tube I2 and engages the contact at the bottom of the insulator bushing 6b. The arm 19 of the bridging members extends through a slightly oversized opening in the baffle 10 into engagement with the contact at the lower end of the bushing lb. The baiile 10 is provided with three nozzle like chutes 16a, 16b and 160, one for each phase. Each of these chutes opens at the bottom into the chamber below the baffle 10, which is the pressure chamber, and discharges at the top into the region of the adjacent arc.

The bridging members for three phases are secured together in any desired manner, as for instance, by means of upper and lower cross bars 82-B3 and supported by a pair of rods 84B4 located between the A and B phase and between the B and C phase. This construction is illustrated more fully in my pending application, Serial No. 186,177, filed January 21, 1938. V e

The interior of the circuit breaker above described is thus divided into two chambers. One of the chambers, which will hereafter be referred to as a pressure chamber, includes all of the space below the baflle 1-0 and also the. space within the three tubes 12. The second chamber, Whichis the arc extinguishing chamber, includes all of the space above the bafile except the interiors of the tubes 12.

During circuit interruption the downward movement of the bridging member opens the circuit at the contacts l2 and 12 causing two arcs to be drawn. The expansion of the gas bubble at the arc l2 creates a pressure within the pressure chamber thereby forcing cool oil from said chamber through the chutes such as 161) into the region of the arc at the contact l2. The are at the contact [2' is also being blown outwardly by the magnetic forces resulting from the flow of current in the arc at the contact l2 in the opposite direction to the flow of current at the contact I2. As a result the arc bubble is forced to the right, as seen in Figure 7, by the combined action of the magnetic force and the stream of cool oil flowing upwardly from the pressure chamber through the chute b. The are at the contact I2 is thus quickly extinguished, thereby causing interruption of the circuit and extinguishment of the arc at the contact I2. Thereafter the gases in the tube 12 as a result of the arc formation will slowly escape through the top of the tube.

It is to be noted that the tubes 12 and the are chute, for the three phases, are staggered, as is clear in Figure 6. This reduces the unbalanced forces which might otherwise skew the cross bars 82-83 carrying the contact making structures for the three phases due to the fact that one end of each contact making assembly is in the pressure chamber and the opposite end is outside of the pressure chamber.

Reference may now be had more particularly to Figures 8 and 9. In this circuit breaker the contact and contact making structure is the same as in the breaker of Figures 6 and '7. Here, however the bafiie 10 of Figure '7 has been entirely omitted. Instead the contact I2 has been surrounded by an oversized tube of insulation, indicated at 99, which constitutes a pressure chamber. This tube or pressure chamber has an opening in which is fitted a short tube 9!, constituting a nozzle, which opens adjacent the contact l2 so that oil discharged from the pressure chamber 80 through the nozzle 9| will be blown into the region of the arc at the contact l2. When this circuit is opened the expanding are formed at the contact I2 forces oil'from the tube 90 through the nozzle 9| to flow with great rapidity into the region of the are at the contact 12, since the tube 90 is full of oil and devoid of compressible media. The rapid movement of cool oil from the opening 9| into the arc at I2 causes quick extinguishment of the are at l2 and resulting circuit interruption. Non-condensing gases formed by the arc in the pressure chamber 90 slowly escape from said chamber through the top thereof, the chamber being provided with restricted openings at the top, or being made to fit around the bushing 61) with sufficient looseness to permit such esape of gas while at the same time preventing a rapid escapeof oil during circuit interruption. In this circuit breaker, as in the circuit breaker of Figures 6 and '7, the pressure chambers for the three phases are staggered on opposite sides of the longitudinal center line of the breaker thus minimizing any unbalanced forces on the switch operating mechanism. Also, the tubes of insulation around alternate contacts prevent arc-over between adjacent phases. It is also to be noted that the pressure in the pressure chamber acts upon the contact making structure to force the same downwardly, which is the direction of switch opening movement. At the place where the contact making member enters the arcing chamber 90 there is provided a comparatively close fit between the movable contact making structure and the arcing chamber to prevent any appreciable loss of oil fromthe arcing chamber through the space between the movable structure and the chamber wall. Thus the total unbalanced force on the movable contact making structure or bridging members is of a magnitude equal tothe difference of pressure on the two sides of the longitudinal center line of the breaker, due to the staggered arrangement of the arcing chambers 90.

Reference may now be, had more particularly to the switch illustrated in Figure 10. In this construction the circuit breaker tank is divided in two by a horizontal partition or baflie Ill-l. corresponding to the bailie 10 of Figure 7, and provided with an insulating tube 1.2 loosely surrounding the contact which generates the pressure developing arc. The essential difference between this construction and the construction illustrated in Figure 7 lies in the fact that the chute 16 has been omitted so that all of the oil which is set into motion by the pressure generating arc escapes from. the pressure chamber I02 by way of an opening 103 in the .bailie I'M. In this construction the are at the contact I2 is blown outwardly by the magnetic forces due to the current flow, as heretofore described, and the upwardly moving stream of cool oi-l flowing through the opening I03 tends to cool and blow out the arc which is formed at the contact [2. An insulating brace N15 is provided for supporting the top portions of the three tubes 12. The oil level in the circuit breaker extends slightly above the top of the tube 12,, and the top of this tube is arranged to permit the slow escape of gases therefrom which are formed during the circuit interruption. In the circuit breaker illustrated in Figure 10 themes-- sure generating arcs which are surrounded by the tubes 12 are arranged in staggered relationship, as inFigures -6 or 8. As a result the pressure generated during the circuit interruption is ineffective to exert undue bending stresses on the beam carrying the contact making members for the three phases, and the contacts at adjacent phases are separated by solid insulation of the tubes.

Reference may now be had to the circuit breaker illustrated diagrammatically in Figure 11. In this circuit breaker the top of the tank is closed by an insulating plate or barrier I I-5 which has three depending insulating tubes lI-G, one

for each phase, in staggered relationship as in --:construction illustrated in Figure 7. Th pressure chamber III is filled with oil up to the barrier H so that there are no gases or other compressible media within this chamber. During circuit interruption the are formed at the contact I2 causes a pressure to be generated within the pressure chamber I I1 thereby causing a rapid flow of oil from said chamber upwardly through the tube H6. This flowing oil serves to cool and extinguish the arc formed at the contact I2, which are has been bowed outwardly by the magnetic forces, as heretofore explained. One or more restricted openings is provided in the barrier H5 to permit the slow escape of gases formed in the pressure chamber as a result of the circuit interruption. In this breaker a lowering of the tank will expose the contact I2 for inspection or repair purposes. If the contact I2 is to be inspected then the tube IIB may be forced upwardly through the barrier H5 to expose that contact.

Reference may now be had to Figure 12. This figure shows a circuit breaker arrangement similar to that of Figure 11 except that the bridging member, indicated at I20, is not of a U-shape, as in the breakers previously described. In this construction the bridging member I extends through a slot I2I and insulating tube I22 that loosely embraces the contact I2. This tube is open at both the top and the bottom. The circuit breaker is filled with oil to a level slightly above the bottom of the barrier H5 so that the pressure chamber III is entirely devoid of gases or other compressible media. Upon circuit interruption the are formed at the contact I2 causes oil to flow from the pressure chamber through the opening I2I and the bottom opening in the tube, and upwardly through the tube I22 into cooling relationship to the arc that has been formed at the contact I2 and has been bowed outwardly by the magnetic forces. The upwardly moving cool oil thus serves to extinguish the arc and thus interrupt the circuit.

Reference may now be had to Figure 13 which shows a circuit breaker having a contact making member of an L-shape, that is, half of the contact making member is of the shape of the contact making member of Figure 7 and the other half is of the shape of the contact making member of Figure 12. In this construction the pressure chamber is formed by a horizontal insulating barrier I extending across the circuit breaker tank and provided with three upwardly extending tubes of insulation I3I, one for each phase, around the bushing that carries the contact which is to form the pressure generating arc. The barrier I30 is provided with three openings, one for each phase, through which the arm I32 of the contact making structure extends. A tube of insulation I33, slotted at the side to permit vertical movement of the bridging member therein, is provided for the contact making structure of each phase. Oil from the pressure chamber I35 which is set into motion by the expanding arc bubble formed at the contact I2, flows through the three openings I36, adjacent the region of the are formed at each of the contacts I2 and serves to cool and blow out those arcs. The pressure generating arcs for the three phases and the tubes I3I surrounding the corresponding bushings are staggered on opposite sides of the center of the circuit breaker to prevent the exertion of undue twisting stresses on the contact making members, and to afford solid insulation between contacts of adjacent phases.

Reference may now be had to the arrangement illustrated in Figures 14 and 15. This circuit breaker employs a movable contact making bridging member I20, as in Figure 12, which moves through a vertical slot in a tube I that extends downwardly from a barrier plate HI and a similar slot in a tube I42 that extends both upwardly and downwardly from the barrier plate I4 I. The oil level in this circuit breaker extends above the top of the tube I42. On opening of the circuit the pressure generated by the expanding arc bubble at the contact I2 forces fresh cool oil upwardly through the tube I40, past the region of the are at the contact I2, and into the portion of the circuit breaker above the barrier I4I. This serves quickly to cool and extinguish the arc formed at the contact I2, and thus interrupt the circuit.

In Figures 16 and 17 I have shown still another arrangement whereby the pressure generated by one are is effective to force cool oil into the region of another are in series therewith to interrupt the circuit. In this diagram I have shown an ordinary circuit breaker wherein one contact of each phase is enclosed in a casing I of insulation which extends almost but not quite to the other contact. The bridging member I20 moves through a vertical opening I5I in the casing I50. The casing I50 constitutes a pressure chamber. This chamber is full of oil and devoid of any gases or other compressible media. Upon the formation of an are at the contact I2, upon downward movement of the bridging member I20, the expanding arc bubble forces oil from the pressure chamber I50, through the opening I5I, into the region of the arc formed at the contact I2, thus blowing that are outwardly and interrupting the circuit. The top of the pressure chamber I50 is provided with one or more restricted openings for permitting the slow escape of gases formed in the pressure chamber by the arc, but preventing any rapid escape of oil during circuit interruption.

Reference may now be had to the circuit breaker illustrated in Figure 18. This circuit breaker is a single phase breaker particularly adapted for interrupting high voltage circuits. The circuit breaker includes the usual tank 2 0I suspended from a circuit breaker head 202 and filled with insulating oil or other are extinguishing liquid insulation to a level appreciably above the contacts therein, to be presently described, and only slightly below the juncture between the tank and the circuit breaker head.

Inclined insulator bushings

203 and 204 extend into the breaker, through which conductors such as 205 extend. Each bushing has a contact structure and oil blast pressure chamber at the end thereof, indicated in general by the reference numeral 206, and illustrated more fully in Figures 19 to 1 inclusive. The contact structure includes a contact stud 2l0 screwed or otherwise secured to the conductor 205 in intimate current transfer relation. The contact 2l0 has a metal disc 2H threaded thereon, which disc is threaded at its outer periphery and receives an insulating cylinder 2I2, the inside of which constitutes the explosion chamber 201. The cylinder 2I2 is closed at its bottom by a metal disc 2I3 threaded into the cylinder and having a central bore in which is threaded a metal thimble 2I4. A hollow tubular contact 2I5 closed at its upper end and slotted at 2 I5 is slidable through the thimble 2I4 and is normally maintained in the position illustrated in Figure 21, when the circuit breaker is open. It is maintained in such position by gravicircuit breaker is open.

ty assisted by a coiled spring 2l6. i The spring bears at its lower end against a peripheral flange 2!! at the bottom of the floating contact 215. A rod, disc, or other projection 219 secured to the hollow tubular contact 2!5 limits the downward movement of the contact 2!5 to the position illustrated in Figure 21. At its upper end the contact 2 5 is adapted to engage the contact stud 2!!! to establish circuit connections therewith.

The two structures 226 for the respective incoming conductors of the circuit breaker are connected together by an insulating bar 220 which serves to brace the structure. This bar also acts as a guide for a vertically movable opcrating rod 22! (Fig. 18) that carries a metallic bridging member 222 at its lower end. The bridging member 222 has two similar sliding contact making members 223, one at each end. The construction of the slidingcontact making member 2 23 is illustrated more fully in Figures 19 to 21. This contactmaking member comprises a tube of copper that is closed at the bottom and is sli'dable through the bridging member 222 and connected therewith by a flexible braided or other conductor 224 that is soldered or otherwise secured to the bridging member and to the contact 223 to maintain electrical connections therebetween. A coiled spring 226 urges the contact 223 upwardly and maintains the contact in the position illustrated in Figure 21 when the The upper end of the tubular contact 223 is provided with a flat peripheral flange 22'! the top of which serves as a contact making surface.

To close the breaker illustrated in Figure 18 the operating rod 22! is moved upwardly from the dotted line position. The surface 22'! of the contact 223 ultimately engages the surface 2!! of the floating contact 2!5. diate position illustrated in Figure 20. Further 'upward movement of the bridging member 222 causes upward movement of the floating contact 2!5 and compression of the spring 2!6. The

top of the contact 2!5 ultimately engages the contact stud 2!!) thus establishing circuit connections. Continued further upward'movement of the bridging member 222 causes compression of the spring 226 without further upward movement of the contact 223 or the contact 2 !5. This continues until the bridging member reaches its full switch closed position, illustrated in Figure During circuit interruption the bridging member 222 is caused to move downwardly. The.

initial downward movement of the bridging member produces no effect upon the contacts until the bridging member has reached a position engaging the projection 228 of the contact 223. By that time the bridging member has attained a considerable velocity. Further downward movement of the bridging member causes a rapid downward movement of the contact 223. The contact 2!5 follows the contact 223 without disengagement of the two at the surfaces 2!!22!. This results in the formation of an are between the contact 2!5 and the contact 2), within the pressure chamber 2!2. The expanding bubble of gas within the pressure chamber'forces oil from the pressure chamber, through the openings 2!5 in the contact 2!5, as well as through the top opening at the tubular contact 215. This oil sets up a pressure within the continuous tube constituting the floating contact 2!5 and the contact 223. Should the This is the inter-mepressure become excessive that pressure will'be' eifective to force the contact 223 downwardly at a speed greater than the speed of the moving bridging member 222. Ultimately the surface 22! separates from the surface 2I'I. The separating movement may be the result of the pressure created within the explosion chamber 251 or it may be the result of the downward movement of the bridging member 222 after the downward movement of the contact 2!5 has been stopped-by the engagement of the projection 2I9 with the metal disc 2!3. Immediately upon separation of the contact making surfaces 2!!- 22'! a second arc is formed between these surfaces in series with the are between the contact 2!!) and the contact 2!5. Oilimmediately flows from the pressure chamber, by reason of the pressure created therein by the expanding. gas bubble, said oil flowing through the tubular contact 2!5 and out through the space between the separated contacts 2!5 and 223. This cool oil quickly blows out and extinguishes the last formed arc, thus interrupting the circuit and causing extinguishment of the first formed are within the pressure chamber.

An important characteristic of the pressure chamber and contact making arrangement of the circuit breaker of Figure 18 is the impossibility of building up an excessive pressure in the oil blast chamber 231. Should the pressure exceed a predetermined value during the switch opening operation and before the tubular .contact 205 has moved to its limit of travel where the projection 2 9 engages the metal disc 2! 3, the pressure will be exerted against the contactv 223, which is closed at the bottom thus forcing it downwardly against the restraining pressure of its spring 225, thereby opening a gapbetween the surfaces 2!! and 22'!, through which gap the excess pressure is relieved. This action is similar to that of a safety valve. Furthermore, in case of a heavy flow of current this characteristic permits the gap outside of the oil blast chamber, that is, the gap between the surfaces 2!! and 22'!, to be formed and an arc drawn there, which are is subjected to the extinguishing action of the oil blast even before the gap inside the chamber has extended to its maximum permissible length. This characteristic tends to speed up the interruption of the circuit.

If the circuit breaker illustrated in Figure 18 is intended for carrying currents in excess of approximately 1200 amperes, the bridging member 222 may be provided with a contact which cooperates with another contact permanently electrically connected with the conductor 205, which last mentioned contacts shunt the arc extinguishing contacts previously described during the normal operation of the circuit breaker in its closed position. On commencement of the switch opening operation, that is, when the bridging member is moved downwardly from the position illustrated in Figure 19 to a point immediately preceding the engagement of the bridging member 222 with the projection 228, the shunting contacts are opened thus by-passing all of the current to the arcing contacts. Such an arrangement is illustrated in Figure 2 of the United States patent to William E. Paul, No. 1,904,519, of April 18, 1933, to which reference may be had.

In compliance with the requirements of the patent statutes I have here shown and described a few preferred embodiments of my. invention.

It is, however, to be understood that the invention is not limited to the precise constructions here shown, the same being merely illustrative of the principles of the invention. What I consider new and desire to secure by Letters Patent is:

1. In a switch, a tank adapted to contain an insulating liquid, means dividing the tank into two communicating sections, cooperating contacts arranged to form two arcs in series in said tank one in one section and the other in the other section with the current in the two arcs flowing in opposite directions and each in the electromagnetic field produced by the other to produce forces tending to blow at least one of the arcs outwardly, and means whereby the fluid under pressure created by one of the arcs is directed into the path of the other are and in an upward direction.

2. In a switch, a tank adapted to contain an insulating liquid, cooperating contacts separable in the liquid to draw an arc in a generally vertical direction, means for bowing the arc magnetically, and means including a second are for directing a blast of insulating liquid in the region of the first arc bubble in a generally vertical upward direction whereby the blast of liquid assists the natural buoyancy of the arc gas bubble to break the bubble between the contacts.

3. A circuit breaker of the type including a tank and circuit connection in the tank including means for interrupting the circuit by drawing two arcs in series with one of the arcs in such relation to the current path through the circuit connections that magnetic forces are produced tending to force that are in a direction at a substantial angle to the arc path, means dividing the tank into two communicating sections each containing one of the arcs, one of the sections being full of insulating liquid and devoid of substantially compressible media so that the gas bubble formed by the arc therein forces liquid into the other section, the arc in the other section being in the path of the resulting liquid flow.

4. A circuit breaker of the type including a tank and circuit connection in the tank including means for interrupting the circuit by drawing two arcs in series with one of the arcs in such relation to the current path through the circuit connections that magnetic forces are produced tending to force that arc in a direction at a substantial angle to the arc path, means dividing the tank into two communicating sections each containing one of the arcs, one of the sections being full of insulating liquid and devoid of substantially compressible media so that the gas bubble formed by the arc forces fluid into the other section, the arc in the other section being in the path of the resulting fluid flow, the two arcs being separated by substantially the entire body of insulating liquid within the tank, which body of insulating liquid is in the path of travel of liquid from one are to the other.

5. An electric circuit breaker comprising a container, means dividing the container into two communicating chambers, an insulating bushing extending into the container and terminating in a contact member in one of the chambers, a second insulating bushing extending into the container and terminating in a contact within the other chamber, a conducting bridging member extending between the chambers and bridging the contacts, said bridging member being movable out of engagement with the contacts to draw two arcs in series and located one in one chamber and the other in the other chamber, one of the chambers being full of an insulating liquid and devoid of gases so that the pressure generated by an arc in said one chamber forces liquid therefrom to flow into the other chamber, and the arc in said other chamber being in the path of the liquid flow.

6. A circuit breaker of the type including a tank and circuit connections in the tank including means for interrupting the circuit by drawing two arcs in series with one of the arcs in such relation to the current path through the circuit connections that magnetic forces are produced tending to force that arc in a direction at a substantial angle to the arc path, an enclosure in the tank surrounding only one of the arcs, and means including the enclosure for creating a flow of insulating fluid in the region of one of the arcs by the pressure produced by the other are.

7. In a circuit breaker of the liquid-break type, a tank containing insulating liquid, a pressure chamber in said tank and filled with said insulating liquid and vented at the top to permit the restricted escape of the gaseous products of a circuit interruption, a switch contact in the chamber, a contact making member engaging the contact and including means retractible through the chamber within the tank for separating the contact making member from the contact and drawing an arc whereby the pressure produced by the are within the chamber assists in the retraction of the means and thus facilitates the switch opening operation, and said chamber having a liquid discharge opening spaced from the region of the are and from the part of the chamber through which the retractible means extends, said opening discharging liquid from the chamber into the tank, and means for drawing a second arc in said tank but outside of the chamber, said second are being in series with the first arc and in the path of the discharging liquid.

8. In a circuit breaker of the liquid-break type, a substantially tubular arcing pressure chamber having a filling of insulating liquid and vented at the top to permit the restricted escape of the gaseous products of a circuit interruption, a switch contact in the chamber, a contact making member engaging the contact and including means retractible through the chamber for separating the contact making member from the contact and drawing an arc whereby the pressure produced by the are within the chamber assists in the retraction of the means and thus facilitates the switch opening operation, and said chamber having an opening for the escape of liquid therefrom upon the development of pressure therein, the opening being spaced from the region of the arc and from the part of the chamber through which the retractible means extends, and means for forming an are outside of the chamber in series with the are within the chamber and adjacent the said chamber outlet.

9. In a circuit breaker of the liquid-break type, a container for liquid insulation, a closure barrier dividing the compartment into two sections each containing insulating liquid, said barrier having an opening therein for permitting the flow of liquid from one section into the other, circuit interrupting contacts in the path of flow of fluid through the barrier, a second set of circuit interrupting contacts, and a tubular member extending from the barrier into one of the sections and loosely surrounding one of the sets of contacts so that one arc is drawn in the tube, and the other are is drawn outside of the tube.

10.. In acircuit breaker'of the liquid-break type, a tank, and an arcing pressure chamber within the tank and comprising a substantially tubular body containing insulating liquid and closed against the rapid movement of liquid-from the same at the ends thereof and having a-discharge opening in the tubular wall adjacent the lower end thereof and discharging into the tank.

'11. A circuit breaker including "a container, liquid insulation in thecont'ainer, bush-ings extending downwardly into the-liquid in the container, conductors extending through the bushings and terminating in switching contactsin the insulating liquid, a conducting bridging member bridging the contacts and movable downwardly out of bridging engagement to draw-two arcs in series, a horizontal barrier across the container and dividing the same into two communicating compartments with one compartment devoid of compressible media, a tube sealed to thebarrier and extending vertically therefrom into one of the compartments, said tube opening into at least one of the compartments and loosely surround ing one of said arcs, the other are being entirely outside of the tube.

12. A circuit breaker including a container, liquid insulation in the container, bushings extending downwardly into the-liquid in the; container, conductors extending through the bushings and terminating in switching-contactsin the insulating liquid, a conducting bridging member in bridging relation to the contacts and movable downwardly out of bridging engagement to draw two arcs in series, a horizontal barrier across the container and dividing the same into, two communica-ting compartments with thelower compartment devoid of compressible media, a tube sealedto the barrier and extending'vertica lly upward therefrom into one of the compartments, said tube opening at the bottom into the other compartment and beingsubstantiallyfclosed at the top and loosely surrounding one. of said arcs, the other are being entirely outside of the tube, and the are that is outside of the tube being above the barrier and adjacent the path of flow of insulating liquid through the barrier by the pressure developed by the arc in the tube.

13. A circuit breaker including a container, liquid insulation in the container, bushings extending downwardly into the liquid in the container, conductors extending through the bushings and terminating in switching contacts in the insulating liquid, a conducting bridging member in bridging relation to the contacts and movable downwardly out of bridging engagement to draw two arcs in series, a horizontal barrier across the container and dividing the same into two communicating compartments with the lower compartment devoid of compressible media, a tube open at both ends and sealed to and extending vertically of said barrier and providing a communicating passageway between the compartments and loosely surrounding one of said arcs, the other are being entirely outside of the tube.

14. A polyphase circuit breaker including a container, liquid insulation within said container, means for drawing a plurality of arcs in said container, there being at least two arcs in series per phase, means dividing the container into a pressure section and another section, in communication, at least one are per phase being located in the pressure section and at least one are per phase being in said other section.

15. A polyphase circuit breaker including a container, liquid insulation within said container,

means for drawing a plurality of arcs in said container, there being at least two arcs in series per phase, means dividing the container into a pressure section and another section, in communication, :atleast'one arc per phase being located mine-pressure section and at least one are per phase bein-g' in said other section, the pressure sectionbeing full of insulating liquid and substantiallydevoid of compressible gases whereby expandingarc gas bubblesin the pressure section force liquid therefrom into the other section,- and each of the arcs in said other section being in the path of moving insulating liquid which is set into motion by the pressure created by the arcs in the pressuresection.

16. A polyphase circuit breaker including a container, liquid insulation within said container, means for drawing a plurality of arcs in said container, there being at least two arcs in series periphase, means-dividing the container into a pressure section and another. section, in communi'oati'on, at leastone arc per phase being located in. the pressure section and at least one arctperiphjase beinglin said other section, the meansidivilding the container into the two sections. being of insulation. and so'arranged that adjacent aricsiofaadjacent phases are indifferent ones'ofthel twIorsections.

' 17; A: polyphase circuit breaker including a container, liquid insulation within said container, means for drawing .a plurality of arcs in said container; there being at least two arcs in-series per phase, means dividing the container into a pressure section andlanother section, in communication, at least Zone are .per phase being locatedin ,the pressuresection and at least one arc-per; phase being inrsaid other section, the means dividing: the: container into two sections including a central; vertical barrier between the arcs of the:- same phaseQwith one surface. of the barrier in the high pressure. section-. an'd' an opposite surface thereof in the'otherTsectionf l8-.E,An electric..fcircuit breaker comprising a container;,means.for drawing two arcs in series in the container and spaced from one another on opposite sides of a vertical line through the container, means dividing the container into a pressure section and another section, said dividing means including a vertical barrier between the arcs, said barrier terminating above the bottom of the container and having a horizontal insulator extending from the bottom of the barrier toward the container wall, the space on one side vertically of said horizontal insulator being the pressure section and on the other side vertically of said horizontal insulator being the other section, insulating liquid filling the pressure section and insulating liquid in the other section, said horizontal insulator having an opening for the fiow of liquid between the sections, one of the arcs being in the pressure section and remote from the said opening whereby the pressure generated by that are forces insulating liquid to fiow from the pressure section through. said opening into the other section, the other arc being in the path of said flowing liquid.

19. An electric circuit breaker comprising a container, means for drawing two arcs in series in the container, means dividing the container into a pressure section and another section, said dividing means including a vertical barrier between the arcs, said barrier terminating above the bottom of the container and having a horizontal insulator extending from the bottom of the barrier toward the container wall, the space on one side vertically of said horizontal insulator being the pressure section and on the other side vertically of said horizontal insulator being the other section, insulating liquid filling the pressure section and insulating liquid in the other section, said horizontal insulator having an opening for the flow of liquid between the sections one of the arcs being in the pressure section and remote from the said opening whereby the pressure generated by that are forces insulating liquid to flow from the pressure section through said opening into the other section, the other are being in the other section and in the path of said flowing liquid.

20. An electric circuit breaker comprising a container, means for drawing two arcs in series in the container, means dividing the container into a pressure section and another section, said dividing means including a vertical barrier between the arcs, the space on one side of the vertical barrier being the pressure section and the space on the other side being the other section, insulating liquid filling the pressure section and insulating liquid in the other section, means forming a cylinder below the top of the level of insulating liquid in the container and having a piston movable therein, the part of the cylinder on one side of the piston opening into the pressure section and the part of the cylinder on the other side of the piston opening into the other section.

21. An electric circuit breaker comprising a container, means for drawing two arcs in series in the container, means dividing the container into a pressure section and another section, said dividing means including a vertical barrier between the arcs, the space on one side of the vertical barrier being the pressure section and the space on the other side being the other section, insulating liquid filling the pressure section and insulating liquid in the other section, means forming a cylinder below the top of the level of insulating liquid in the container and having a piston movable therein, the part of the cylinder on one side of the piston opening into the pressure section and the part of the cylinder on the other side of the piston opening into the other section in the region of the arc in the other section.

22. An electric circuit interrupter comprising a tank containing insulating liquid, a pair of spaced switch contacts, and bridging means connecting the contacts and movable out of bridging relation thereto to interrupt the circuit, an insulating barrier wall between the contacts, operating means extending through the barrier and connected to the bridging means for operating the same, and means associated with the operating means within the barrier and forming a dash pot retarding the opening movement of said bridging means at a predetermined point.

23. In a circuit breaker of the liquid-break type, means forming a pressure chamber, a filling of insulating liquid therein, a contact making member movable therein to draw an arc in the chamber, a pressure relief safety valve for said chamber in series with the contact making member, said safety valve being movable outside of the chamber and drawing an arc outside of the chamber in series with the first named arc and in the path of flow of liquid through the safety valve, and means including the safety valve for moving the contact making member to the switch closed position.

24. In a circuit breaker of the liquid-break type, means forming a pressure chamber, a filling of insulating liquid therein, a contact making member movable therein to draw an arc in the chamber, a pressure relief safety valve for said chamber in series with the contact making member, said safety valve having a movement outside of the chamber and drawing an arc in series with the first named arc and in the path of flow of liquid through the safety valve, and switch actuating means for opening th safety valve to draw the second are independently or the pressure in the pressure chamber.

ALLEN M. ROSSMAN.