US2678983A - Compressed gas circuit interrupter - Google Patents

Description

May 18, 1954 A. P. STROM COMPRESSED GAS CIRCUIT INTERRUP'IER Filed lay 16. 1950 I I7 J "I: -1 "'I ,4 46 L.

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3 SheetsHSheet 1' INVENTOR Albert P. Sirom May 18, 1954 A. P. STROM 2,673,983

cou azsssu GAS cmcurr INTERRUPTER Filed lay 16. 1950 3 Sheets-Sheet 2 e s 4| 6 s i -C l 5 19 U L1 L1 LP --59 F G Fig.4.

I l I l WITNESSES: INVENTOR f Albert P. Strorn.

A BY g. A: W @54 4 Patented May 18, 1954 UNITED STATES PATENT OFFICE COMPRESSED GAS CIRCUIT INTERRUPTER Albert P. Strom, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 16, 1950, Serial No. 162,369

16 Claims.

This invention relates to circuit interrupters in general, and, more particularly, to arc-extinguishing structures therefor.

A general object of my invention is to provide an improved compressed-gas arc-extinguishing structure of improved construction which will more efiectively interrupt the circuit therethrough than has heretofore been attained.

A more specific object is to provide an improved gas-blast extinguishing structure in which the extinguishing gas blast is more efiectively directed into the arcing region and in which the arc length is held to a minimum distance.

Still another object is to provide improved contact faces for an arc-extinguishing structure of the gas-blast type.

Still another object is to provide a contact construction in which the gas flow not only assists in extinguishing the are but carries the arc in a desired direction to the contact faces.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the accompanying drawings, in which:

Figure 1 is a vertical sectional view through a gas blast type of circuit interrupter embodying my invention, the contact structure being shown in the open circuit position;

Fig. 2 is a vertical sectional view through a modified type of arc extinguishing structure, the contact structure being shown in the closed oi-- cuit position and the valve partly open;

Fig. 3 is a plan View of the contact insert of Fig. 2;

Fig. 4 is; modified. type of contact insert which may be used in place of that of Fig. 3;

Fig. 5 is a modified type of contact construction which may be used in place of that of Fig. 2, the contacts being shown closed and the blast valve partly open;

Fig. 6 is a fragmentary vertical sectional view of a modified contact structure in. which segmental contact inserts are employed;

Fig. '5 is a. view of the contact insert of Fig. 1, taken along the line VII-47H cf Fig. 1;

Fig. 8 is a modified type of contact construction which may be used employing concentrically disposed cyiindrical tubes;

Fig. 9 is a plan view of the segmental contact insert of 6;

Fig. 10 is a plan view of a contact insert of Fig. 8 utilizing concentric tubes;

Fig. 1. is a plan view of the contact insert of i Fig. 12 is an embodiment of invention simi- 2 lar to that of Fig. 5 but showing modified type are catchers; and

Fig. 13 shows modified type are catchers.

In the study of air blast interrupters, it has been found that only short distances between electrodes are required to hold high restored voltages after the current is interrupted, providing a gas pressure of several atmospheres is maintained on the arc space following interruption. The construction of such interrupters, however, usually permits the arc to elongate so as to have a length much longer than this minimum distance necessary to hold the maximum restored voltage. Permitting the are to thus elongate is undesirable because the are energy that must be carried away by the air flow is practically directly proportional to the arc length, and, therefore, if the arc is longer than necessary clogging, that is stoppage of air flow by the expanding gas surrounding the arc, will occur at a lower current than if the arc is kept to its shortest possible length. The interrupting capacity oi the breaker is thus reduced if the arc is longer than necessary.

Other difficulties in conventional air blast interrupters are: (1) Low gas velocities in the approaches to the orifice, that sometimes permit high current arcs to move back out of the high velocity fiow at the orifice. (2) Location of the gas inlet valve far away from the interrupting orifice produces a time lag in air fiow through the orifice, so that air is not available until some time after the arc is drawn.

The construction which is more fully described hereinafter shows means of constructing gas blast circuit interrupters in such manner as to eliminate these objectionable features in conventional interrupters.

I propose to utilize the double orifice type of interrupter since I believe it lends itself best to designs for short are lengths, and hence it is proposed to use this type with modifications. In order to prevent arcs from elongating and still maintaining an orifice of sufficient area to discharge the heat-expanded gas from arcs of very high currents, each of the orifices is modified from a single hole to a perforated surface which consists of about half of the area metallic, and the remainder of discharge passages, the individual discharge passages being narrow in width, so that are terminals of high current arcs would not be blown into the discharge passages.

With the foregoing principles in mind, reference may be had to the drawings, with particular attention being directed to Fig. l. The reference character I designate a cup-shaped relatively stationary contact having a plurality of discharge openings or passages 2 therethrough. The stationary contact I has a cylindrical wall portion 3 which is threadedly connected as at 4, to an apertured conducting plate 5. The plate 5 is secured by bolts 6 to the upper insulating wall 7 of the extinguishing structure 8. Preferably the top wall or plate I is circular and rests upon a cylindrically-shaped member 9 formed of insulating member.

It will be noted that the stationary contact I is perforated by the plurality of discharge passages 2, the contact face or insert consisting of a plurality of conducting bars I I more clearly shown in Fig. 7.

Cooperating with the stationary contact I is a movable tubular contact I2, also perforated and having a plurality of discharge openings 2 therethrough. Fig. '7 more clearly shows the construction of the movable contact face or insert I2, which again consists of a plurality of conducting bars II constituting a grating surface. The movable contact I2 is of tubular configuration and has an outwardly extending flange I3 integrally formed therewith. The flange I3 has a lost-motion connection I4 with a movable valve member I5, the latter cooperating with a valve seat I6 formed at the lower end of the stationary contact I. fingers I I are carried by the movable valve I 5 so that no arcing occurs between the valve faces I5 and I6.

In the closed circuit position, not shown, the valve faces I 5, I6 constitute main contact surfaces for conducting the line current through the interrupter, as more clearly explained hereinafter.

The valve member I5 is cylindrical in configuration and at the lower end thereof has a slotted wall portion I8. An actuating ring I9 is secured by screws 21! to the lower end I8 of the movable valve member I5. An operating lever 2I pivotally mounted at a stationary pivot 22 serves to move the valve member I5 to its closed position against the biasing action exerted by an opening accelerating compression spring 23. A toggle, generally designated by the reference numeral 24, is provided having links 25, 25, which when extended by an operating rod 2! serve to make the toggle 24 and move the valve member I5 upwardly to its closed position.

A compression spring 28 is provided to move the movable contact I2 to its closed. position wherein arcing portions 29, 30 make contacting engagement before the valve member I5 has been moved upwardly by the toggle 24 against the valve seat I G. If desired, a Sylphon bellows 3i may be provided to prevent leakage of the high pressure gas existing within the high pressure region 32 within the extinguishing structure 8 out past the sliding metallic surfaces.

Flexible conductors 33 electrically interconnect the movable tubular contact I2 with a ring 34, the latter having attached thereto a line terminal S5. The ring 34 is threadedly connected, as at 36, to a metallic bushing 31, the latter being threaded, as at 38, to the lower plate 39 of the extinguishing structure 8.

An inlet blast tube 48 enters the extinguishing structure 8 from any suitable external supply of compressed gas, preferably compressed air.

In the closed circuit position of the interrupter, not shown, the electrical circuit therethrough includes line terminal 4I, bolt 6, plate Preferably contact 5, stationary contact I, valve seat I 6, movable valve member I5, movable contact I2, fiexible conductors 33, ring 34 to line terminal 35. In the closed position the toggle 24 is extended, and the compression springs 28 and 23 are under compression. The compression spring 23 tends to open the movable valve member I5, and the compression spring 28 maintains contact pressure between the arcing ring portions 29, 3B of the contacts I, I2 respectively. Initially high pressure gas is present within the region 32, being fed therein by means of the conduit 49. The gas pressure may range from 50 pounds per square inch, or even lower, up to 300 pounds per square inch or higher, and the gas may be compressed air.

It will be noted that in the closed circuit position of the interrupter there are two shunt circuits around the main contacts I5, I6. One circuit extends through the movable contact I2 and stationary contact I. The other circuit extends through the contact fingers Il, which in the closed position make engagement with the inner wall portion 42 of the stationary contact I. The arrangement is such that during the opening operation, the main contacts I5, It or cooperating valve members, separate prior to separation between the contact fingers I1 and the contact ing portion 42 of stationary contact I. Following separation of the secondary contact structure, including fingers I! and contacting portion 42, the tertiary or arcing contacts 29, 30 separate to actually draw an arc therebetween. The purpose of the three sets of contact surfaces is to avoid any burning at the main valve surfaces I5, I6, which would result in gas leakage past the valve seat I6.

During the opening operation, the toggle 24 is broken by rightward movement of the operating rod 21. This rotates the lever 2 I in a clockwise direction about pivot pin 22 thereby permitting the compression spring 23 to move the movable valve member I5 downwardly. During this time the stationary and movable contacts I, I2 make engagement because of the compression or" the compression spring 28. When the valve face I5 separates away from the valve seat It, compressed air within the region 32 flows upwardly between the conducting tubes 3', I2. The electrical circuit by-passes the main contacts I5, I5 by means of the fingers I1 and also by means of the contacting engagement between the contacts 29, 36.

Further downward movement of the movable valve member I5 causes separation to occur between the contact fingers I? and the contacting portion 42 of stationary contact I. The electri: cal circuit now extends through the arcing portions 29, 38 of contacts I and I2 respectively.

Continued downward opening motion of the valve member I5 causes the flange portion 43 thereof to strike the flange I 3 picking up the movable contact I2 and moving the latter downwardly with the valve member I5 thereby resulting in a separation betwen the arcing ring portions 29, 30. An are 4 1 is consequently established between the arcing rin portions 2 9, 3S and is struck by the upward blast of compressed gas passing through the annular space 45. The gas blast exhausts out through the discharge openings 2 in the directions indicated by the arrows.

The downward opening motion of the valve member I5 and movable contact I2 continues under the biasing action exerted by the compres sion spring 23 until a shoulder 4% of movable valve member I5 strikes the upper face ii of the bushing 31. This halt'sthe opening motion of the: movable parts of the interrupter. The gasblast passing upwardly within the annular'space 45 effects extinction of the arc 44 which may be carried tothe position 48. It will b observed'that'the are 48 is kept short since, because of thegrating' surfaces II, the ends of thearc are not allowed to loop through the discharge openings 2;

If desired a suitable shunting resistance B. may be employed in some instances, but if this is done, then preferably a disconnect switch 49 is employed to break the'residual currentpassing through the interrupter.

In some instances itmay be desirable toutilize contact having in place of the gratings l'l segmental discharge openings 50, as indicated more clearly in Figs. 6 and 9. These segmental dis charge openings are formed as a result of using a contact face 5! having segmental contact portions or bars 51s, as shown in Figs. 6 and 9.

Also it may be desirable in certain instances to utilize contact faces formed of concentrically positioned conducting cylinders 52, as more clearly shown in Figs. 8 and 10. The purpose of'having the contact surface perforated with a plurality of discharge openings, preferably having'a width of the order of or of an inch, is to keep the arc length short and to prevent the looping through the contacts I, I2. A mentioned previously, such elongation of the arc, or such looping of the arc through the contact, faces results in an increase in are energy which must be dissipated. This are energy, if excessive, heats the entering gas blast and creates a local high pressure condition which tends to clog the entrance of the incoming blast of gas. By keeping the are short and preventing any such looping, the are energy is kept to a minimum and unnecessary heating'of the blast of gas is'avoided;

Figs. 2, 3 and 4 illustrate a modification of my invention in which the contacts 55; 58 are stationary, the contact 55 being cup-shaped in configuration with the tubular contact 56 extending therein. The contact 56 is of cylindrical shape havin an elongated wall portion 51; the lower'end of which is thread-connected, as at 58, to an exhaust tube 59. The conducting tube 51 is also threaded, as at 60, to a sleeve 6|, thelatter'being threaded at 62 to a bushing 63. The bushing 63 is secured by bolts 64 to the lower'plate 33-of the extingui hing structure 65. A line terminal connection 66 is clamped between the sleeve 61 and a was. er 61, compression being exerted by the exhaust tube 59.

Surrounding the stationary tube 51 is a movable ring-shaped' piston member 68. The piston member 68 a small gas passage 69 extending therethrough so that in the closed circuit position shown, compressed gas exists under pressure within. the regions andH. The; gas pressure maybe removed from the region H by anexhaust passage 12 exhausting to air, and which may be controlled by an electrically operated solenoid valve, not shown. Thus, exhausting of high pressure gas from the region 1| below the piston 58 through the exhaust passage 12 will cause rapid downward opening movement of the piston 68.

The piston 38 carries a movable valve sleeve 13 which cooperates with a stationary valve seat 14. Secured by screws to the movable valve sleeve 13 is a plurality of bridging contact fingers 16 which make engagement with the inner portion 11 of the'stationary contact 55.

Thus exhausting of high pressure gas out of iii) the region H through the exhaust passage 12- by; any suitable pneumatic control will result in the high pressure gas within the region 10 forcing the piston 68 and hence the fingers i6 and valve member 13 downwardly. The separation between the valve surfaces 13, 14 permits high pressure gas within the region Hi to pass upwardly past the fingers 16 within the annular space 18 to exhaust out through the apertures 2, in a manner indicated by the arrows. No arc, however, is drawn until separation of the contact fingers 76' from the inner contacting portion '51. When such separation between the fingers l8 and contacting portion 1! does occur, an arc is drawn therebetween which is blown upwardly by the upward flowing gas blast within the annular space 1' to the stationary contacts 55, 56 where are extinction takes place in a manner previously described. Also, the u netic forces assist upward travel of the ir ally drawn arc. This follows since the circuit looped upwardly from plate 5 to portion H and then down the finacre 76.

In some instances a shunting resistance R may be desirable, and'if it is, an externally operated disconnect switch 49 must be employed to break the residual current passing through the interrupter.

Fig. shows the particular contact insert which may be used. Again bars ll of conducting material may be employed so that the contacting approximately half the discharge area. In certain instances it may be desirable to utiiize a contact face or insert in which an apertured button it, as shown in Fig. 4, is employed in conjunction with the conducting. bars H. The contact button T5 may be better able to withstand the arcing than using merely the bars ll themselves.

A washer 83 is preferably employed to stop the downward opening travel of the piston 63, and as long as conduit ?2 remains open to atmosphere, the contact structure will remain open and gas will continue to exhaust out of the extinguisher 55 past the valve fees 73, 2'4.

Toclose the interrupter, the valve controlling the discharge conduit '12; not shown, is closed so that high pressure pass from the region T0 through the bleed opening 59 to the region it below the piston c3. When the pres-- sures within the regi ns "i9, 7! b come somewhat equalized, the coin-pr vsion cpl-i1 Bl will become operative to force the piston pwardiy closing the valve surfaces 74, 73 and making en merit between. the finger contacts 75 and the contacting portion ll. The interrupter is then closed.

Fig. 5 shows a modidcation of the interrupter of 2 which may be ipioyed in place of the contact structure or" i Referring to Fig. it wiil be noticed that have employed a pair of arc catch electrodes 84, onthe dischar chare p n 86, 81 of the s ionary contacts 38, 55. Inserts 82, shown in 1i, be used for the contacts 82' The re structure may be the same as shown in 2. A suitable spider structure SI, 92 may be employed to maintain the arcing electrodes 84, S5 in a position of presas that consequently inereiy tobe noted blis 3: upon separa- -l the contacting hing ti desci connection it will not us repeated. that the are initially portion 11 will be carried upwardly through the annular space 78 t the contacts 88, 39, where the ends of the arc will be carried by the blast of gas to the arcing electrodes 64, 85. The arc will then be in the position indicated at 94. The gas blast will engage the are 94 at the midportion thereof, and will flow in opposite directions through the discharge openings 88, 81 to deionize the arcing space and bring about extinction of the arc 94.

In certain instances it may be desirable to utilize the resistance R as mentioned heretofore.

Preferably the discharge passages between the bars I l are substantially to 1% Wide. The bars H may be substantially 1%" wide. The contact face may be 1% in diameter. The

The contact I" ace contact spacing may be 1%. of Fig. 4 was tried with discharge passages a, wide. Also preferably the cross-sectional area of the annular space it, or 45, is only slightly larger than the total discharge area of the orifices. Such an arrangement is superior to mounting the orifices in parallel flat plates because the air velocity for the latter case decreases inversely as the radius, whereas the velocity between the concentric tubes remains constant with distance from the orifice. With such high velocities in the approach regions, the arc will always tend to move toward the orifice even though it should strike elsewhere.

It will also be observed from the above constructions that with the tubular arrangement of the contacts it is also a simple matter to provide an air inlet valve very close to the discharge orifice, thereby practically eliminating any time lag in application of air pressure after the contacts part.

Fig. 12 shows a contact arrangement identical to that of Fig. 5 except that modified arc catchers or arcing electrodes 84a, 85a are employed. These arcing electrodes 84a, 85a are slightly smaller in diameter than the arcing electrodes 84, 85 of Fig. 5 and extend through the discharge openings 86, 81 flush to the inner sides of the contacts 88, 89, as shown in Fig. 12. The arcing electrodes 84a, 85a are provided respectively with discharge orifices 96, 9?, respectively, to permit some flow of compressed gas through the arcing electrodes 84a, 85a, themselves. If the discharge orifices 9B, 91 were not provided, the are 94 might remain in an area of flow stagnation along the axis between the orifices 89, 97 where the flow velocity approaches zero. This is desirable during the high current period of the half cycle since less are energy is produced, but as current approaches zero, deionization proceeds more slowly than if the are extended through the turbulent regions of the orifice discharge area 8B, 81.

By providing the arc catchers 84a, 85a with central holes 96, 91 through which a small part of the gas flow is discharged, it results that during high current the arc terminal will not enter the holes 96, 97 and the arc voltage correspondingly remains low during the high current portion of the half cycle. But as the current approaches zero during the half cycle, the central core of the are 94 can be discharged through the small holes 96, 5?, and the arc terminals are carried into the central holes 96, 9? provided in the arc catchers 84a, 85a, thereby lengthening the are 94 and subjecting it to a turbulent gas blast.

Another modification of such an arc catcher with slight restrictions in the discharge orifices 98, 99 is shown in Fig. 13 of the drawings. It will .be noted that the modified type of arcing elec- 8 trodes 84b, 85b have discharge orifices 98, 99 extending therethrough, as was the case in Fig. 12, but here there is a restriction at the points I00, llll.

By adding the slight restrictions I 00, "ll in the discharge orifices 98, 99 of the arcing electrodes 84b, 85b, respectively, the full length of the are up to these restrictions as current zero is approached is under high pressure and hence has greater dielectric strength. Again during the high current portion of the half cycle, the arc 94 remains between the electrodes 84b, 851) as shown in Fig. 13, and it is only near a current zero, that is during low instantaneous values of arcing current that the arc will stretch through the holes 98, 99 to have its terminal ends be disposed at the points I02, I03.

In all the constructions it is desirable to have a pressure drop of 10-25% of tank pressure in the concentric approach passage '13, 45 to the contacts, and the remainder -75% pressure drop available at the orifices. This provides high approach velocity and high pressure on the arc space. Also, the valve seats may be made of a compressible material such as rubber or plastic,

and the contact fingers l6 serve as main contacts.

The foregoing description shows how I have provided an improved compressed gas circuit interrupter in which are voltage and are energy are kept to a minimum, and a more efiective gas flow is provided to bring about rapid arc extinction. It will also be noted that use has been made of magnetic forces to assist in moving the arc along the direction of flow of the compressed gas stream. I have disclosed how several different types of contact structures may be employed, and I have also disclosed a novel disposition of the contact elements so as to most effectively utilize the gas blast Although Ihave shown and described specific structures, it is to be clearly understood that the same were merely for the purpose of illustration, and that changes and modifications may readily be made by those skilled in the art without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. A gas blast circuit interrupter including a cup-shaped relatively stationary contact having a discharge orifice therethrough, a cooperable tubular contact projecting within the first said contact prior and during arc extinction and spaced therefrom at least during a portion of the opening operation, the second said contact having a discharge orifice therethrough, a valve seat, a movable valve member surrounding the second said contact and cooperating with the valve seat to open an annular gas blast passage between the two contacts, means for establishing an are between the two contacts, and the infiowing gas blast between the two contacts extinguishing the arc.

2. A gas blast circuit interrupter including a cup-shaped relatively stationary contact having a plurality of closely spaced discharge orifices therethrough, a cooperable tubular contact projecting within the first said contact prior and during arc extinction and spaced therefrom at least during a portion of the opening operation, the second said contact having a plurality of closely spaced discharge orifices therethrough, a valve seat, a movable valve m mber surrounding the second said contact and cooperating with the valve seat to open an annular gas blast passage between the two contacts, means for establishing'an are between the two contacts,=and the inflowing gas blast between the two contacts extinguishig the arc.

3. A gas blast circuit interrupter including a cup-shaped relatively stationary contact having .a. discharge orifice therethrough, a cooperable tubular contact projecting within the first said contact prior and during arc extinction and .spaced therefrom at least during a-portion of the tween the two contacts, the i flowin gas blast between the two contacts extinguishin the arc, and a pair of arcing electrodes at the exhaust sides of the discharge isages to which the ends of the arc may attach.

4. A gas blast circuit interrupter including a cup-sha d stationary contact having a discharge orifice theretlirough, a cooperable stationary tubular contact proj within the first said contact a substantial distance and spaced therefrom, the second said contact having a discharge orifice therethrough, avalve seat, a tubular movable valve surrounding the second said contact,

a movable piston carrying the rnovable'valve,

gas blast means for moving the piston, and rnovable bridging contact means carried by the movable piston and bridging the two contacts in the closed circuit position of the interrupter.

5. A gas blast circuit interrupter including a tubular stationary contact-having a plurality of discharge open ngs therethrough, an arcing portion jutting aw y from the arcing surface of the contact, cocperable movable contact extending within the first said contact prior and during arc extinction and havin a plurality of discharge openings therethrcugh, a second arcing portion on the second said contact also jutting away from the arcing surface, means for separating the contacts so that the arc is initially established with the ends thereof on the two arcing portions, and means for sending an annular blast of gas inwardly between the contacts and outwardly in opposite directions through the discharge openings.

6. A gas blast circuit interrupter including a tubular stationary contact having a plurality of discharge openings therethrough, an arcing portion juttin away from the arcin surface of the contact, a cooperable movable contact extending first said contact prior and during e on and having a plurality of discharge openings therethrough, a second arcing portion on the second said contact also jutting away from the arcing surface, and means for sending a blast of gas inwardly between the contacts and outwardly in opposite directions through th discharge openings, said last-mentioned means including movable gas blast valve means connected by a lost-motion connection to the said movable contact.

'7. A gas blast circuit interrupter including a pair of contacts spaced apart at least during a portion of the openin operation, each contact having a plurality of segmental discharge openings, means for establishing an are between the contacts, and means for forcing a blast of gas between the contacts and outwardly in opposite directions through the segmental discharge openings.

inwardly betw 8. A gas blast circuit interrupter including a pair of tubular contacts with end perforated arcing portions, one contact projecting inside of the other contact so that the endarcing portion of the outer contact shields the end arcing portion of the inner contact, said one contact projecting inside of the other contact prior and durin arc extinction, valve means surrcin din the inner contact for controlling flow 0" s between the tubular contacts, and the gas l owing radially the end arcing portions of the contacts otwardly in opposite directions throng veriorated arcing portions.

9. c cuit interrupter including a pair electrodes, one electro-zlepr w nin the other electrode prior and duri e of arc extinction, each electrode ha tin r B one discharge opening therethrough, means Ior s-e ling a blast of gas between the electrodes and o l; through the discharge openings, 10-25% drop or pressure occuring in the concentric approach region between the electrodes, and 9G75% drop of pressure available at th discharge openings.

10, A gas blast circuit interrupter including a pair of cooperable contacts having discharge passages therethrough, means for establishing an are between the two contacts, means ior establishing a radially infiowing blast of gas between the two contacts and then in opposite directions out through the two discharge passages, and a pair of arcin lectrodes extending within the discharge passages to which the ends of the arc may attach, andat least one of the arcing electrodes having a discharge orifice therethrough.

ii. A gas blast circuit interrupter including a pair of cooperable contacts having discharge past-herethrough, means for establishing an are between the two contacts, means for establishing a radially inflowing blast of gas between the two contacts and then in opposite directions out through the two discharge passages, and a pair of arcing electrodes extending within the discharge passages to which the ends of the arc may attach, and both arcing electrodes having discharge orifices therethrough.

12. A gas blast circuit interrupter including a pair of substantially coaxial cup-shaped members having cooperable arcing electrodes at least at the interior ends thereof, each electrode having a discharge orifice therethrough, one electrode projecting within the other electrode prior and during the time of arc extinction, the cooperable arcing electrodes being spaced apart at least during a portion of the opening operation, a valve seat, a movable valve member surrounding the interior cup-shaped member and cooperating with the valve seat to open an annular gas blast passage between the members, means for establishing an are between the cooperable arcing electrodes, and the infiowing gas blast between the arcing electrodes passing in substantially opposite directions outwardly through the discharge orifices to effect extinction of the established arc.

13. A gas blast circuit interrupter including a pair of coaxial cup-shaped electrodes, each electrode having at least one discharge opening therethrough, one electrode projecting within the other electrode prior and during the time of arc extinction, means for sending a blast of gas between the electrodes and out through the discharge openings, 10-25% drop of pressure occurring in the concentric approach region between the electrodes, and -75% drop of pressure available at the discharge openings, a valve seat associated with the outer end of the outer cup-shaped electrode, a blast valve surrounding the interior cup-shaped electrode and cooperating with the aforesaid valve seat to control the passage of a blast of gas between the cup-shaped electrodes and outwardly through the discharge openings, and the blast of gas effecting extinction of the arc between the electrodes.

14. A gas blast circuit interrupter including a pair of substantially coaxial cup-shaped members having cooperable arcing electrodes at least at the interior ends thereof, each electrode having at least one discharge opening therethrough, one electrode projecting within the other electrode prior and during the time of arc extinction, means for sending a blast of gas between the cupshaped members and out through the discharge openings, 10-25% drop of pressure occurring in the concentric approach region between the cupshaped members, and 90-75% drop of pressure available at the discharge openings.

15. A gas blast circuit interrupter including a pair of substantially coaxial cup-shaped members having cooperable arcing electrodes at least at the interior ends thereof, each electrode having at least one discharge opening therethrough, one electrode projecting within the other electrode prior and during the time of arc extinction, means for sending a blast of gas between the cup-shaped members and out through the discharge openings, 10-25% drop of pressure occurring in the concentric approach region between the cup-shaped members, and 90-75% drop of pressure available at the discharge openings, a valve seat associated with the outer cupshaped member, a. blast valve cooperating with the aforesaid valve seat and surrounding the inner cup-shaped member to control the passage of the blast of gas between the cup-shaped members and out through the discharge openings.

16. A fluid-blast circuit interrupter including a pair of contacts spaced apart at least during a portion of the opening operation, means for establishing an are between the contacts, at least one of the contacts having a grating-like contact face including a plurality of spaced radially extending conducting bars with radially extendin discharge openings therebetween, the inner ends of the conducting bars being close together to prevent looping of the terminal of the are within the contact, the conducting bars being immovable with respect to each other and extending in the plane of the contact face, and means for forcing a blast of fluid between the contacts and interiorly of said one contact through the discharge openings to effect extinction of the arc.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,961,475 Clerc June 5, 1934 1,987,885 Whitney et al. Jan. 15, 1935 2,427,195 Cox et a1. Sept. 9, 1947 2,440,995 Wilcox May 4, 1948 2,481,996 Grunewald et a1. Sept. 13, 1949 2,551,772 Thibaudat May 8, 1951 2,561,192 Forwald July 17, 1951 2,588,933 Latour Mar. 11, 1952 FOREIGN PATENTS Number Country Date 418,737 Great Britain Oct. 30, 1934 602,966 Great Britain June 7, 1948 916,754 France Oct. 26, 1946

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