US2762890A - Interrupter with barrier plates forming a u-shaped passage - Google Patents

Description

Sept. 11. 1956 P TAYLOR AL 2,762,890

INTERRUPTER WITH BARRIER PLATES FORMING A U-SHAPED PASSAGE Filed April 27, 1953 2 Sheets-Sheet l Sept. 11, 1956 P. L. TAYLOR ETAL 2,752,390

INTERRUPTER WITH BARRIER PLATES FORMING A U-SHAPED PASSAGE Filed April 27, 1953 2 Sheets-Sheet 2 United States Patent INTERRUPTER WITH BARRIER PIJATES FORMING A U-SHAPED PASSAGE Philip L. Taylor, Abington, and Joseph M. Ramrath,

Mattapan, Mass., assignors to Allis-Chalmers Manufactlli'lllg Company, Milwaukee, Wis.

Application April 27, 1953, Serial No. 351,261 8 Claims. (Cl. 200-150) This invention relates to circuit interrupters and more particularly to are extinguishing structures therefor.

More specifically this invention relates to a novel structure for efiecting the very rapid extinction of electric arcs drawn in circuit interrupters. This invention is applicable to the interruption of high voltage arcs such as those drawn in 287 kv. circuit but is also applicable on low volttage circuits.

Experience has demonstrated that a rapid lowering of the dielectric strength of an arc extinguishing fluid, such as oil, occurs after it impinges upon the arc stream. It is therefore desirable to eliminate such contaminated fluid as quickly as possible, and to subject the arc stream to the action of flesh fluid of high dielectric strength. The isolation or disconnection of a capacitance load by a circuit breaker in an alternating current system is subject to transient overvoltages, the magnitudes of which depend on the capacitance of the load, the voltage of the system, and the type of the circuit breaker. In isolating such a capacitance load, interruption at the first current zero in the arc of the leading current is readily eifected at a relatively small contact separation. In one-half cycle after the first current zero, the voltage of the source has reversed to its crest value, and approximately double this voltage appears across the circuit breaker contacts as a circuit recovery voltage. Whether or not restriking of the arc occurs depends on several factors, such as the type of the circuit breaker, including the speed and the magnitude of the separation of its contacts, the magnitude of the circuit recovery voltage, and the leading kv.-a. of the load. Y

These circuit conditionsare difficult if not impossible to control. Therefore, restriking in most breakers must be expected especially under severe operating conditions, and the circuit interrupting structures must operate efliciently under such conditions.-

In accordance with this invention, a new and improved circuit interrupting structure is provided in which an arc interrupter is immersed in arc extinguishing fluid. The interrupter comprises a pair of contacts comprising a movable contact and a stationary contact separable to draw an arc. An arc extinguishing device comprising a plurality of barrier plates is arranged adjacent the contacts and defines a passageway extending through the barrier plates axial-1y of the device. Means are provided for separating the contacts for establishing an are within the passageway. The arc extinguishing device is provided with a U-shaped guiding means comprising a flow passageway forming one leg of the guiding means, a plurality of nozzles arranged to direct substantially all of the fluid passing through the guiding means acrosss the arc passageway laterally thereof and forming the bight of the guiding means, and means defining a venting passageway forming the other leg of the guiding means leading from the nozzle. A piston operatively connected to the movable contact and movable therewith is provided for forcing fluid through the guiding means and out of the venting passageway to extinguish the arc.

2,762,890 Patented Sept. 11, 1956 It is, therefore, one object of the present invention to provide a new and improved circuit interrupter arranged to draw an arc in which the arc is subjected to un-ionized arc extinguishing fluid forcibly impelled into the arcing region at one or more points along the arc.

A further object of this invention is to provide a circuit breaker to elongate a pair of serially connected arcs in which the pressure generating arc is utilized in a new and improved manner to enhance the arc extinguishing action of the circuit breaker.

A still further object of this invention is to provide a new and improved circuit breaker in which low current arcs are subjected to a plurality of inwardly flowing streams of fluid under pressure which impinge on the arc to rapidly cool and extinguish it.

Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the accompanying drawings in which:

Fig. l is an elevational view partly in section of a circuit interrupter embodying the invention and shown in circuit closed position;

Fig. 2 is an enlarged sectional view through one of the interrupting devices shown in Fig. l and embodying the present invention;

Fig. 3 is an elevational view of the upper disk assembly shown in Fig. 2;

Fig. 4 is a top view of the disk assembly shown in Fig. 3;

Figs. 5 to 12, inclusive, are detailed views of the disks forming the assembly shown in Figs. 2 and 3;

Fig. 13 shows a modification of the disk shown in Fig. 11; and

Fig. 14 is a sectional view of the circuit breaker structure taken along the line XIVXIV of Fig. 2.

Referring to the drawing by characters of reference, Fig. 1 illustrates an oil circuit breaker unit of the high voltage type such as that used in power transmission systems. Unit 1 is suspended from one line terminal of the circuit interrupter in a suitable tank 2 and submerged in a suitable insulating arc extinguishing fluid, such as oil. A conducting bridging bar 3 serves to connect electrically the arc extinguishing unit 1 with an identical unit 4 in a manner well known in the art. Supported on a cover 5 of the tank 2 are a pair of terminal bushings 6 and 7 (partially shown), to the lower ends of which are secured arc extinguishing units 1 and 4. The cross bar 3 is actuated reciprocally in the vertical direction by an insulating lift rod 8 to open and close the contacts of the arc extinguishing units 1 and 4.

Fig. 2 illustrates the internal construction of the are extinguishing unit 1. Clamped to the lower end of a terminal bushing 6 is a conductive housing 11 which forms a conductive path between it and a movable pressure generating contact 16. Contact 16 is arranged in a pressure chamber 41. In the closed circuit position, as shown in Fig. 2, the pressure generating contact 16 engages a stationary or intermediate contact 13, the latter, in turn, engaging a lower extinguishing or interrupting rod shaped contact 14 secured to the extremity of the cross bar 3. Contact 14 is arranged in the pressure chamber 44. Contact 13 comprises two contact engaging surfaces. Contact 16 cooperates with one of the contact engaging surfaces to produce a first arc and contact 14 cooperates with the other of the contact engaging surfaces to produce a second are.

A plurality of rocking finger contacts 15 rest against the upper end of rod shaped pressure generating contact 16. Current is transferred from housing 11 to contact 16 through rocking finger contacts 15. This arrangement dispenses with braids of similar flexible conductors and also eliminates the necessity of the actuating means for the pressure generating contact 16 for carrying current. In other words, there is a complete and desirable segregation of the current carrying function and the contact operating or actuating function.

In the closed circuit position of the interrupting unit 1, asshown in Figs. 1 and 2, the electric circuit therethrough comprises the terminal stud (not shown) in bushing 6, housing '11, finger contacts 15, rod contact 16, intermediate contact13, movable interruptingcontact 14, conducting cross bar 3, movable interrupting contact 14', and the right hand arc extinguishing unit 4 as in housing 11 to the terminal stud '(not shown) in bushing 7.

Contact 16 is actuated by a lever 17 having an oblong hole 18 in one end thereof and adapted to. be rocked about a stud 19. A pin in rod 16 engages oblong hole 18 inlever 17. A cradle 20 is journaled to lever 17 by lowered and rocks about pin 21 relative to lever 17 simultaneously with its raising or lowering movement. The circuit breaker unit 1 may employ contacts 16 and 13 alone or in combination with spring actuated oil pump 12 for the interruption of line charging currents and such low .value of inductive currents as are not effectively interrupted by other types of devices.

7 A valve disk 27 is loosely mounted on rod 23 and biased againstthe piston 24 of pump 12 by a spring 23. Spring 28 is disposed between the valve disk 27 and a flange 29 secured to housing 11. The piston 24 is provided with a plurality of apertures 30 which form a passageway for oil flow under certain conditions between the upper and lower portions of the housing through piston 24. The apertures are controlled by disk 27.

' During a circuit closing operation of the interrupter, the bridging contact member or bar 3 forces the operating rod 25 upward; Operatingrod 25 in its upward mover'n'ent rotates arcing contact lever 17 counterclockwise to cause contact 16 to engage the contactsurfaces of the fixed contact 13. Rod 25 in its upward movement to closed circuit position pushes rod 23 upward against the biasing'a'ction of the spring biased'pis'ton 24 of pump 12. The are interrupting unit 1 utilizes two groups of barrier plate assemblies and 36 of suitably shaped insulating plates .which'forrnpart of the walls of the paths through which the arcs' pr oduced by contacts 16, 13 and 14 are d flw it 7 Each interrupting unit is provided with two parallel cylindrical resistor assemblies 4-5. The upper'end ofeach resistor assembiyfesns' conductiv'ely connected. 'to an electrostatic shield 46." Shield 46' is conductively' connected tohousing 11 which in turn'is conductively connected to the lower terminal end of the breaker bushing 6. The lower end of each resistor assembly 45 is conductively connected to the lower electrostatic ,shield v47. Shield 47 is conductively connected to an'arcing electrode comprising a disk like member 48 through a conductive circuit comprising bolts 49, plate 50, bolts 51 and ring support 52.

V The lower end of the arc interrupting blast chamber 44 comprises an insulating nozzle 55 forming a fluid opening 56. The arcing electrode 48 is secured within chamber 44 between the lower end of the barrier plate assembly 36 and the opening 56.

When it is desired to open the electric circuit passing through the interrupter, or when oyerload conditions exist in the electric circuit controlled by the interrupter suitable operating mechanism (not shown) moves the insulating lift rod 8 to result in a downward movement of the conducting cross bar 3 and the movable contacts 14, 14'.

The downward movement of crossbar 3 causes insulating operating rod 25 to rotate lever 17 clockwise about the pivot stud 19 to draw an arc between contacts and 13. Substantially simultaneously therewith or with a slight delay the movable contact 14 separates from the intermediate 'or fixed contact 13 to draw an are between contacts 13 and 14. The downward movement of operating rod 25 causes the downward movement of piston .24 to move the oilwithin the pump cylinder '26. The

oil, now under. pressure within the pump cylinder 26 flows under pressure out of the cylinder 26 through passageway 37, through .the barrier plate stack 35 transversely of the longitudinal axis of the arc extinguishing unit 1, through the passageway 38 into chamber 39 and through orifice 40 to the inside of tank 2.

As shown in Fig. 2, an aperture may be provided through disk 69 and plate 81 which separates the upper grid assembly 35 from the chamber 44 and particularly from the lower grid assembly 36. This aperture 30 may be omitted if it is desired, to substantially completely isolate the upper chamber 41 from the'lower chamber 44.

If aperture 80 is provided in disk 69 and plate 81 then the are drawn between the contacts 16 and 13 may be called a pressure generating arc and the are drawn between contacts 13 and 14 an interrupting arc. With aperture 80 in disk 69 and plate 81, piston 24 causes a first flow of fluid under pressure through the passageway 37 and through the passageways extending across the barrier plates'of assembly 35. Piston 24 also causes a second flow of fluid under pressure through passageway 37, aperture 80 in disk 69 and plate 81, chamber 44 and into the barrier plate assembly 36. The first blast of fluid under pressure cools and extinguishes the pressure generating arc .and the second blast of fluid under pressure cools and extinguishes the interrupting arc.

During the interruption of low currents, the operating rod 25 moves downwardly at the same speed as the cross bar 3 to result in the lever 17 rotating clockwise about stud 19 to draw an arc between contacts 16 and 13. The rod 23 and piston 24 follow the downward movement of operating rod25. Valve disk 27 closes apertures 30 and moves'the oil in cylinder 26 into passageway 37. This action occurs during the interruption of low currents.

During the interruption of high current arcs, the pressure created by the arc drawn between contacts 16 and 13 may prevent thedownward movement of the piston 24 and this, in turn, halts the downward movement of the rod :23. The cradle 20 then separates from rod 23.

When the pressure subsides within the barrier plate assembly 35 .oil under pressure within housing 26 flows out through barrier plate assembly 35 to flush the region where the arc occurred between contacts 16 and 13. This scavenging action raises the dielectric strength of the oil in the barrier plate assembly 35 ,and prevents restriking between contacts 16 and 13 which would prolong the arcing time .of the interrupter. It also prevents premature breakdown of the contact gap during and immediately following closing operation.

The are extinguishing device or grid assembly 35 defines an arc passageway 59 arranged axially of the assembly 35 and of the circuit interrupting structure. Upon separation of cooperating contacts 13 and 16, a pressure generating arc is drawn therebetween and is established within arc passageway 59. Assembly 35 defines a u shaped guiding means 60 comprising a fiow passageway 61 forrning one leg of the guiding means 60, a plurality of nozzles or flow passages 62 arranged to direct substantially all of thefiuid passing through the guiding means 60 acrosslthe arc passageway 59 laterally thereof and formingthe bight of the guiding means 64), and means. defining a. venting passageway 63 forming the other leg of the guiding means 60 heading from flow passages or nozzles 62. Flow passages 62 may be arranged across the arc passageway 59 in a single direction substantiallyperpendicular to the direction of movement of movable contact 16. Means other than the arcv drawn between cooperating contacts 16 and 13 such as piston pump 12 may be arranged adjacent one end of flow passageway 61 for positively forcing fluid through flow passageway 61, flow passages or nozzles 62, across arc passageway 59, and out the venting passageway 63 directly to the interior of tank 2.

The flow passageway 61, flow passages or nozzles 62, and the venting passageway 63 of guiding means 60 are formed by means of disks 65 to 72 which are shown respectively in Figs. 5 to 12. Disk 71 has substantially butterfly shaped cutout portions extending from the central aperture forming the contact or are passageway 59, with the openings into the flow passageway 61 and the venting passageway 63 being about the width of arc passageway 59.

To clarify the disclosure as to the passages and passageways, the disks in Fig. 3 are numbered to illustrate the sequence used in assembly 35. Each disk has four small apertures through which fastening members 73 extend and hold the assembly disks in proper relation. As shown in Fig. 3, the disks 66 and 71 are alternated through part of the stack assembly 35 so that a plurality of spaced flow passages or nozzles 62 force jets of fluid across the arc passageway 59.

Fig. 3 illustrates the preferred form of the present invention, in which the passages 62 are spaced apart the thickness of one plate or disk 66. However, other sequences of disk arrangement such as a sequence using two disks 66 and one disk 71 or two disks 71 and one disk 66 to form the spaced nozzles 62 may be used and are in- [tended to fall Within the scope of this invention.

The grid assembly 35 is particularly useful in circuit breakers used to isolate a capacitive load of such capacitance and voltage that the voltage gradient across the arc interrupting contacts of the circuit breaker exceeds the dielectric strength between these contacts.

Fig. 13 illustrates a disk lamination 83 which may be substituted for disks 71 in the stack illustrated in Fig. 3. The particular design of disk 83 and particularly the apertures forming parts of the passageways 62 will provide higher velocity, prolonged flow characteristic in the region of contact separation than its counterpart of Fig. 3, namely, disk 71.

For efiicient circuit breaker operation it is desirable to provide an arc extinguishing device adjacent the pressure generating are as well as the interrupting arc.

The downward movement of contact 14 draws an arc in the barrier plate stack assembly 36 between contact 14 and the fixed contact 13. The arc drawn between contacts 13 and 14 breaks down a portion of the are extinguishing liquid which surrounds the arc saturating the barrier plate assembly 36. The barrier plate assembly 36 may be of the type shown and claimed in U. S. Patent No. 2,467,542, P. L. Taylor, April 19, 1949. This type of barrier plate assembly provides helical passages which produce a helical flow of liquid through the barrier plates and the contact passageway 32 formed therein.

Most of the disks shown in the barrier plate assembly 36 have three cutout sections 84, which sections are aligned in the stack to form longitudinal venting passages 85. As the contact passage 32 extends downward through the barrier plate assembly 36, vents 86 extending from the contact passageway 32 to the longitudinal venting passage 85 are provided at intervals as shown in Fig. 3. Venting passages 85 communicate with a plurality of exhaust ports 87 provided in the insulating shell 88 forming a part of the structure of unit 1.

- While the circuit breaker is opening the arcing surface 33 of the movable contact 14 passes the arcing electrode 48 before passing through nozzle 55. Part of the body of contact 14 moves through the nozzle during interruption of the power arc. Immediately after momentary interruption at a current zero the returning voltage between contacts 13 and 14 cause current to flow through the resistor assembly 45 because the voltage breaks down the gap between contact 14 and arcing electrode 48 (due to the short gap between the electrode 48 and the body of contact 14 as compared with the main interrupting gap between surface 33 and contact 13). The resistor assembly 45 is thereby inserted in series with the power circuit through an auxiliary are so that the resistance circuit now shunts the contacts 14, 16 and 13.

The magnitude of the arc current is correspondingly decreased by the resistance and the ditficulty of completely interrupting the current is greatly diminished, particularly in the case of circuits having high rates of increase of the recovery voltage and also in the case of capacitance switching. The ohmic value of the resistance 45 depends on the characteristics of the circuit to be controlled.

When the comparatively weak arc current through the resistor is finally extinguished by the cooling eifect of the oil, further downward movement of contact 14 serves to increase the oil gap for isolating the contacts from each other so that there is no danger of flashover or restriking of the arc.

Thus, an eflicient, simple and compact interrupting unit is provided that occupies practically no more space within the oil tank than conventional interrupting chambers and that is easy to inspect or repair. The resistor unit can be readily removed from the breaker and replaced independently of the chamber and the contacts therein so that complete disassembly of the chamber construction is unnecessary.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a circuit interrupter immersed in arc extingushing fluid, a stationary contact comprising two contact engaging surfaces, a first movable contact cooperating with one of said contact engaging surfaces to produce a pressure generating arc, a second movable contact cooperating with the other of said contact engaging surfaces to produce an interrupting are, a first arc extinguishing device comprising a plurality of barrier plates, said barrier plates of said first device defining an arc passageway extending axially from said one contact engaging surface through said barrier plates, a plurality of flow passages comprising substantially axially aligned inlet and outlet portions leading into and out of said are passageway laterally thereof, a flow passageway arranged transverse ly to and connected with said flow passages, and a venting passageway leading from and transversely of said flow passages, means for moving said first movable contact through said are passageway of said first device to extend said pressure generating are, means other than said are for forcing fluid through said flow passageway and said fiow passages into engagement with said pressure generating arc and through said venting passageway, a second arc extinguishing device comprising a plurality of parallelly arranged barrier plates defining a second arc passageway extending from said other contact engaging surface through said barrier plates of said second device, and means for moving said second movable contact through said second arc passageway, said second device cooling and extinguishing said interrupting are.

2. In a circuit interrupter immersed in arc extinguishing fluid, a stationary contact comprising two contact engaging surfaces, a first movable contact cooperating with one of said contact engaging surfaces to produce a pressure generating arc, a second movable contact cooperating with the other of said contact engaging surfaces to produce an interrupting are, a first arc extinguishing device comprising a plurality of barrier plates, said barrier plates of said first device defining an arc passageway extending axially from said one contact engaging .7 surface through said barrier plates, a plurality of fiow passages momprising substantially axially aligned inlet and outlet portions arranged to direct substantially all of =theflu id passing through saidpassages into and out of said are passageway in a single direction substantially perpendicular :to the direction of movementof said first movable contact, -a flow passageway arranged transversely to and connected with said flow passages, and a venting passageway leading from and transversely of said flow passages, means for moving said first'movable contact through said are passageway of said first devic to extend said pressure generating are, means other than said arc for forcing fluid through said flow passageway and said flowpassages into engagement with said pressure generating are, a second arc extinguishing device comprising a plurality of parallelly arranged barrier plates defining a second arc passageway extending from said other contact engaging surface through said barrier plates of said second device, and means for moving said second movable contact through said second are passageway, said second device cooling and extinguishing said interrupting are.

3. In a circuit interrupter immersed in are extinguishing fluid, a stationary contact comprising two contact engaging surfaces, a first movable contact cooperating with one of said contact engaging surfaces to produce a pressure generating are, a second movable contact cooperating with the other of said contact engaging surfaces to produce an interrupting are, a first arc extinguishing device comprising a plurality of barrier plates, said first device defining an arc passageway extending axially from said one contact engaging surface through said barrier plates, means for moving said first movable contact through said are passageway of said first device to provide a gap between said first contact and said first contact engaging surface, guiding means within said first device and surrounding said first movable contact and said gap fordefining a plurality of nozzles to direct substantially all of the fluid passing through said gap in a single direction substantially perpendicular to the direction of movement of said first movable contact, said nozzles comprising a plurality of flow passages comprising substantially axially aligned inlet and outlet portions leading into and out of said are passageway, said guiding means defining a flow passageway arranged transversely to and connected with said flow passages and means defining a venting passageway leading from and transversely of said flow'passages, means other than said are for positively forcing fluid through said guiding means and into engagement with said pressure generating are, a second are extinguishing device comprising a plurality of parallelly arranged barrier plates defining a second arc passageway extending from 'said other contact engaging surface through said barrier plates of said second device, and means for moving said second movable contact through said second arc passageway, said second device cooling and extinguishing said interrupting are.

4. In a circuit interrupter immersed in arc extinguishing fluid, a stationary contact comprising two contact engaging surfaces, a first movable contact cooperating with one of said contact engaging surfaces to produce a pressure generating are, a second movable contact cooperating with the other of said contact engaging surfaces to produce an interrupting arc, a first arc extinguishing device comprising a plurality of barrier plates, said first device defining an arc passageway extending axially from said one contact engaging surface through said barrier plates, means for moving said first movable contact through said arc passageway of said first device to provide a gap between said first contact and said first contact engaging surface, U-shaped guiding means arranged within thebarrier plates of said first device and surrounding said first movable contact and said gap comprising a flow passageway forming one leg of said guiding'means, apluralit'y of nozzles comprising substantially 'axially aligned inlet and outlet portions arranged to'direct substantially all of-the fluid passing through said guiding means' through said gap in a single direction substantially perpendicular to the direction of movement of said first movable contact forming the bight-of :said guiding means, and means defining aventing'passageway forming theother leg of said guiding means leading'from said nozzles, means other than said are for positively forcing fluid through said flow passageway and said, guiding means and into engagement with said pressure generating are, a second arc extinguishing device comprising a plurality of parallelly arranged barrier plates defining a second arc passageway extending from said other contact engaging surface through said barrier plates of said second device, and means for moving said second movable contact through said second arc passageway, said second device cooling and extinguishing said interrupting are.

5. In a circuit interrupter immersed in arc extinguishing fluid, a first arcing chamber, a second arcing chamber, a stationary contact arranged to extend within 'both'of said chambers and comprising a contact engaging surface in each chamber, a first movable contact cooperating with said contact engaging surface in said first chamber to produce a pressure generating are, a movable contact cooperable with said contact engaging surface in said second chamber'to produce an interrupting arc, a first arc extinguishing device arranged in said first chamber and comprising a-plurality of barrier plates arranged transversely of said pressure generating are, said first device defining a first arc passageway extending from said one contact engaging surface through said barnier plates, U-shaped guiding meanswithin said plates of said first device comprising a flow passageway forming one leg of said guiding means, aplurality of nozzles arranged to direct substantially all of the fluid passing through comprising substantially axially aligned inlet and outlet portions extending into said first passageway on opposite sides thereof and said guiding means across said are passageway laterally thereof, said nozzles forming the bight of said guiding means, and means defining .a enting passageway forming the other leg ofsaid guidingmeans leading from said nozz-les, means for moving said first movable contact through said first passageway of said first device to extend said pressure generating arc, a piston operatively'connected to said first movable contact and movable therewith for causing a flow of fluid through said guiding means, across said are passageway of said first device and through said venting passageway to cool'and extinguish said pressure generating arc, a second arc extinguishing device arranged in said second chamber and comprising a plurality of barrier plates arranged transversely of said interrupting arc to cool and extinguish said interrupting arc.

-6. In a circuit interrupter immersed in arc extinguishing fluid, a pair of cooperating contacts comprising a movable contact and a stationary contact, an arc extinguishing device comprising a plurality of barrier plates arranged adjacent said contacts, said device defining an arc passageway extending axially of said device and through said plates, means for separating said contacts for establishing an arc within said are passageway, U- shaped guiding means within said plates comprising a flow passageway forming one leg of said guiding means and a venting passageway forming the other leg of said guiding means, and a plurality of nozzles forming the bight of said guiding means, said nozzles comprising substantially axially aligned inlet a-nd outletportions, said portions being arranged on opposite sides of said are passageway and arranged to-direct substantially all of the fluid passing through said guiding means in a single direction across said are passageway laterally thereof, and a piston operatively connected to the "movable contact and movable therewith forcing fluid through said guiding means and out of said venting passageway to extinguish said arc.

'7. In a circuit interrupter immersed in arc extinguishing fluid, a pair of cooperating contacts comprising a movable contact and a stationary contact, an arc extinguishing device comprising a plurality of barrier plates arranged adjacent said contacts, said device defining an arc passageway extending axially of said device and through said plates, means for separating said contacts for establishing an are within said are passageway, U-shaped guiding means within said plates comprising flow passageway forming one leg of said guiding means and a venting passageway forming the other leg of said guiding means and a plurality of nozzles forming the bight of said guiding means, said nozzles comprising substantially axially aligned inlet and outlet portions, said portions being arranged on opposite sides of said are passageway and arranged to direct substantially all of the fluid passing through said guiding means in a single direction across said are passageway laterally thereof, and means other than said are arranged adjacent one end of said flow passageway for forcing fluid through said guiding means and out of said venting passageway to extinguish said are.

8. 'In a circuit interrupter immersed in are extinguishing fluid, a pair of cooperating contacts comprising a movable contact and a stationary contact, an arc extinguishing device comprising a plurality of barrier plates arranged adjacent said contacts, said device defining an are 10 passageway extending axially of said device and through said plates, means for separating said contacts for establishing an are within said are passageway, U-shaped guidin-g means within said plates and surrounding said movable contact comprising a flow passageway forming one leg of said guiding means and a venting passageway forming the other leg of said guiding means and a plurality of nozzles forming the bight of said guiding means, said nozzles comprising substantially axially aligned inlet and outlet portions, said portions being arranged on opposite sides of said are passageway and arranged to direct substantially all of the fluid passing through said guiding means in a single direction across said are passageway laterally thereof, and means other than said are arranged adjacent one end of said flow passageway for forcing fluid through said guiding means and out of said venting passageway to extinguish said are.

References Cited in the file of this patent UNITED STATES PATENTS 2,445,442 Leeds et al July 20, 1948 2,621,273 Friedrich et al Dec. 9, 1952 2,669,629 MacNeill et al. Feb. 16,1954

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