US2462708A - Circuit interrupter - Google Patents

Description

B. P. BAKER ET AL CIRCUIT INTERRUPTER Feb. 22, 1949.

5 Sheets-Sheet 2 Filed Jan. 19, 1945 WITNESSES-I h fnf/arap A4 66045.

ATTORNE:

Feb. 22,, 1949.

Filed Jan. 19, 1945 WITNESSES:

B. P. BAKER EI'AL CIRCUIT INTERRUPTER 5 Sheets-Sheet 3 I INVENTORS Ben 12ml?) 95a remand Fb. 22, 1949. B. P. BAKER ETAL 2,462,708

CIRCUIT INTERRUPTER Filed Jan. 19, 1945 5 Sheets-Sheet 4 WITNESSESZ |NVENTOR5 Bent 00w}; Ffiarer and Wm fbrop M. 166' 1'5.

AT'ToR'N @3122, 1949. B. P, BAKER ETAL 2,462,708

CIRCUIT INTERRUPTER Filed Jan. 19, 1945 5 Sheets-Sheet 5 I? INVENTOR5 Fer/ am //7 PBa/rer 0/10 h/infhrop M (sea 5.

BY I

ATTORNE I WITNESSES:

Patented Feb. 22, 1949 CIRCUIT INTERRUPTE-R Benjamin F. Baker, Turtle Creek,

M. Leeds, Wilkinsburg, inghouse Electric Corporation, East Pittsburgh, Pa, a corporation of Pennsylvania Application January 19, 1945, Serial No. 573,522

11 Claims. 1

This invention relates to circuit interrupters, in general, and, more particularly, to circuit interrupters of the liquid-break type.

An object of our invention is to provide an improved circuit interrupter in which improved operation is obtained both during the interruption of lov. and high currents.

A more specific object is to provide an improved circuit interrupter of the type establishing both a pressure-generating arc and an interrupting arc and to provide piston means associated therewith in a novel manner to assist in the interruption of low currents.

Another object is to provide an improved circuit interrupter in which a pressure-generating arc and an interrupting arc are established in an arc-extinguishing unit and to provide means for magnetically moving the pressure-generating arc laterally to increase the pressme formed thereat.

Further objects and advantages will readily become apparent upon a reading of the following s ecification taken in conjunction with the drawings, in which:

Figure 1 shows a complete circuit interrupter embodying our invention and shown in the closed circuit position;

Fig. 2 is an enlarged vertical sectional view of the right-hand arc-extinguishing unit of Fig. 1, the parts thereof being shown in an intermediate position during the opennig operation;

Fig. 3 is a fragmentary vertical sectional view taken substantially on the line III-III of Fig. 2;

Fig. 4 is a plan view in section taken along the line IV-IV of Fig. 2;

Figs. 5 through '7 show plate details used in the construction of the pressure-generating chamber associated with Fig- 2;

Fig. 8 is a plan view in section taken along the line VIII-VIII of Fig. 2;

Fig. 9 is a plan view in section taken along the line IX-IX of Fig. 2;

Fig. 10 is a plate detail used in constructing the interrupting chamber associated with Fig. 2;

11 is a vertical sectional View of a modified type of arc-extinguishing unit embodying another modification of our invention, the parts being shown in an intermediate position during the opening operation;

Fig. 12 is a vertical sectional view of still another modified type of arc-extinguishing unit embodying our invention, the parts being shown in an intermediate position during the opening operation;

Fig. 13 is a plan view in section taken along the line XIII-XIII of Fig. 11;

and Winthrop Pa., assignors to West- Fig. 14 is a plan view in section taken along the line XIV-XIV of Fig. 11;

Fig. 15 is a plan view in section taken along the line XV-XV of Fig. 12;

Fig. 16 is a plan view in section taken along the line XVI-XVI of Fig. 12;

Fig. 1'7 is a plan view in section taken along the line XVII-XVII of Fig. 12;

Fig. 18 is a sectional view taken along the line XVIII-XVIII of Fig. 12; and

Figs. 19 and 20 collectively illustrate a further modified type of arc-extinguishing unit.

Referring to the drawings, and more particularly to Fig. 1 thereof, the reference numeral I designates a tank filled to the level 2 with a suitable arc extinguishing fluid 3 in this instance, oil, and having a cover 4 from which depend two insulating bushings 5, 6 through which extend terminal studs I, 8. The terminal studs 1, 8 are threadedly secured to contact feet 9, it which support in position two serially related arc-extinguishin units H, l2. The arc-extinguishing units H, I2 are identical in construction.

Reciprocally operable within the tank I and actuated by suitable mechanism, not shown, is an insulating operating rod I4 having rigidly secured to its lower end a conducting bridging member It at the opposed outer ends of which are upstanding portions !6, I1 forming the lower movable contacts of the interrupter. The bridging member l5 carries bumpers l8, [9, the purpose for which will appear more clearly hereinafter.

Referring to Fig. 2, which shows an enlarged vertical sectional view of the right-hand arcextinguishing unit E2 of Fig. 1, it will be observed that the contact foot it supports by bolts 28 a stationary contact housing 21 in which pivotally moves a relatively stationary contact 22 biased downwardly by a compression spring 23 and pivotally mounted at 24. Immediately below the housing 2! is a conducting plate 25 which supports an arcing horn 26. The conducting plate 25 also supports a check valve 27 which closes during high-pressure conditions within the pressure-generating chamber 28, but opens following a subsidence of pressure to permit accumulated gas to pass out of the pressure-generating chamber 28 through the check valve 21 following the completion of an opening operation of the interrupter.

The pressure-generating chamber 23 is iormed. by a plurality of suitably shaped insulating plates maintained in abutting relation by insulating tie rods 29 which extend axially through the unit l2 3 and have nuts 30 threadedly secured to their outer ends.

The insulating plates forming the pressuregenerating chamber 28 are of three types, as shown more clearly in Figs. 5 through 7. Immediately below the conducting plate 25 are positioned two insulating plates 3! having a configuration more clearly shown in Fig. 5. Each insulating plate 3i has apertures 32 formed therein for the accommodation of the tie rods 29 and a large cutout portion 33. Immediately below the plates 31 is a group of three plates, the outer two of which are designated by the reference numeral 3 3 and shown more clearly in Fig. 6. The plates 34 have cutout portions'35, 36 formed therein. Between the two plates 34 is a magnetic insert plate 3'! having a configuration more clearly shown in Fig. 7. The magnetic insert plate also has cutout portions 35, 36, but additionally has inserted therein a U-shaped member 33 composed of a suitable magnetic material such as iron. It will, therefore, be apparent that the two guard insulating plates 34 protect the magnetic insert 38 from contact with the pressure-generating are 39 which is drawn in the pressure-generating chamber 28 during the opening operation. Below the group of two insulating plates 4 and the'insert plate 31 is a plate 3| which is followed by a second group of the plates 34, 31.

The successive ,groups of plates 36, 31 form substantially V-shaped restricting means 340. disposed within the pressure-generating chamber 28. The spacing of these groups of plates 34, 31 as achieved by the plates 3! form a plurality of vent pasages 37a disposed along the V-shaped restricting means 34a.

Movable into engagement with the stationary contact 22 is an intermediate contact 4|. The intermediate contact 41 also moves into a piston chamber, generally designated by the reference numeral 42, and disposed intermediate the ends of the unit Q2. The intermediate contact 4! has an insulating cross-bar 43 rigidly secured to its lower end as shown in Fig. 3. At the opposed outer-ends of the cross-bar Q3 are two insulating operating rods M which are joined at their lower ends by a cross member 45 having a bumper 46 rigidly secured thereto. Encircling the lower end of each of the operating rods 45 and positioned between the bottom plate 37 of the unit [2 and the cross member d5 is a compression spring 48. The two compression springs 48 bias the operating rods M and hence the intermediate contact il downwardly. During the closing operation of the interrupter, the bumper l9 strikes the bumper :25 to raise the operating rods 44 and the intermediate contact lil until the intermediate contact H strikes the stationary contact 22, slightly raising the latter so that the requisite contact pressure therebetween is provided by the compression spring 23,

The volume of the operating rods 445 movable out of the piston chamber :12 during the opening operation is considerably less than the volume of the intermediate contact El movable into the piston chamber 52, the purpose for which will appear more clearly hereinafter.

Associated with the intermediate contact M is a relatively stationary contact 39 pivotally mounted at 5B and biased downwardly by a compression spring 5!. A conductor 52 electrically connects the intermediate contact 5! and the stationary contact 59. Another conductor 53 electrically connects the arcing horn 55 with the stationary contact 49. The piston chamber 42 is substantially enclosed with the exception of a passage 55 which joins the passage 56 leading from the pressure-generating chamber 28 to the interrupting chamber, generally designated by the reference numeral 51 and disposed adjacent the lower end of the arc-extinguishing unit l2. A valve 59 is provided in the passage 55, the purpose for which will appear hereinafter.

The interrupting chamber 57 is formed by a plurality of adjacently positioned suitably shaped insulating plates maintained in abutting relation by the tie rods 29. These plates are of four difierent types, as indicated more clearly in Figs. 8 through 10. The first type is herein called an insert plate and designated by the reference numeral 69 being shown more clearly in Fig. 8. The plate 65 has apertures 32 provided therein to accommodate the .tie rods 29. Also the insert plate 66 has a U-shaped member 6! inserted therein which is composed of a suitable magnetic material, in this instance, iron. The plate 60 also has a cutout portion 62 formed therein and a second cutout portion 63. Immediately above and below the insert plate 68 are two insulating guard plates as of identical shape as the insulating plate 69 with the exception that no magnetic insert 6i is employed. The guard plates 64 protect the insert 6| from the interrupting are 65 which is drawn between the stationary contact 69 and the lower movable contact [1.

Immediately above and below each group of two guard plates 64 and one insert plate 69 is a pocket insulating plate 65 having a configuration more clearly shown in Fig. 10. Each pocket insulating plate 66 has a cutout portion 61 provided therein, the periphery of which defines a plurality of pockets 68 which serve to retain additional liquid adjacent the are 65.

Between adjacent pocket insulating plates 66 is disposed an insulating vent plate 69 and having a configuration more clearly shown in Fig. 9. The vent plate 69 has a cutout portion 10 which vents at H to the region exterior of the unit l2. An insulating cylinder 12 surrounds the upper end of the arc-extinguishing unit l2 and not only provides support, but minimizes leakage out of the unit 12 between the several insulating plates. The cylinder l2 lends considerable strength to the unit [2.

The operation of the arc-extinguishing unit l2 will now be explained. In the closed circuit position of the interrupter, as shown by the full lines in Fig. 1, the electrical circuit therethrough comprises terminal stud 8, contact foot l0, housing 2|, bolt 20, coducting plate 25, stationary contact 22, intermediate contact 4!, conductor 52, stationary contact 49, movable contact l1, bridging member l5, through the left-hand arc-extinguishing unit H in an identical manner to the terminal stud 1.

When it is desired to open the electrical circuit through the interrupter, or in response to overload conditions existing in the circuit controlled by the interrupter, suitable operating mechanism, not shown, is actuated to cause downward movement of the operating rod l4. The downward movement of the operating rod M also causes downward movement of the bumpers l8, I9 and the movable contacts l6, ll. Consequently, considering only the right-hand arc-extinguishing unit l2, the downward movement of the bumper l9 permits the compression springs 48 to move the intermediate contact 4| downwardly away from the stationary contact 22 to draw a pressure-gencrating are 39. At the same time, the movable contact |l separates from the stationary contact 49 to draw an interrupting are 65 within the in! terrupting chamber 51. Assume that the current being interrupted by the unit I2 is high. In this event, the pressure formed in the pressure-generating chamber 28 will be considerable, and furthermore because of the high amperage passingthrough the pressure-generating are 3.9, the magnetic field associated therewith will be greatly distorted by the magnetic inserts 38 to conse quently cause a lateral motion of the pressuregenerating are 39 onto the arcing horns 26 and 54, and toward the right as indicated in Fig. 2. It is apparent that the are 39 is biased to the right by the magnetic inserts 38 more strongly during high-current conditions than during low-current conditions.

Consequently, during the interruption of high current, the pressure-generating are 39 will be strongly aiTected by the magnetic field to. move to the right and into the constriction 13 provided by the plates 34 and 31. The constriction 13 will tend to deionize the are 39 to effect the extinction thereof, and, consequently, there is considerable interrupting ability associated with the pressure-generating chamber 28. The pressure created at the pressure-generating are 38 will close the check valve 21 and act downwardly through the passage 56 to cause opening of the valve 59 and to pass downwardly into the interrupting chamber to tend to force the interrupting are 65 to the left toward the vents 1|.

During relatively high instantaneous values of arcing current, the magnetic inserts 6| will hold the interrupting are 65 toward the right away from the vents l However, during relatively low values of instantaneous arcing current, that is, near a current zero, the biasing force exerted by the magnetic inserts 6| toward the right will be decreased to permit the oil flow to carry the interrupting are 65 to the left toward the vents H to effect the extinction thereof. The oil disposed in the pockets 68 of the insulating pocket plates 66 will provide an additional readily available quantity of oil to be acted upon by the interrupting arc 65 to facilitate the deionizing thereof. The foregoing is assumed to take place during the intterruption of high currents passing through the interrupter.

During the interruption of low currents passing through the interrupter, the pressure generated within the pressure-generating chamber 28 by the pressure-generating are 39 Will correspondingly be low. Consequently, there may not be suflicient pressure formed by the are 39 to effect a rapid extinction of the interrupting are 65 by adequate oil fiow. This is a hazard which is present. during the interruption of charging currents or low value magnetizing currents. To remedy this defect, we have provided the piston chamber 42 into which the intermediate contact 4| moves. This contact displaces considerably greater volume than the operating rods 44 which move out of the piston chamber 42 during the opening operation. The net result is a displacement of oil out of the piston chamber 42 through the passage 55 to cause. closure of the valve 59 and to effect a passage of oil downwardly into the interrupting chamber 51 where the interruption of the are 65 takes place in a manner as previously described. It is to be observed that during the interruption of low currents the pressure-generating are 39 remains with its terminals positioned on the contacts 22 and 4| and does not transfer to the arcing horns 26 and 54. It is only during the interruption of high currents that lateral motion of the are 39 onto the arcing horns 26 and 54 takes place.

The valve 59 is provided to be sure that oil displaced out of the piston chamber 42 will go into the interrupting chamber 51 and will not circulate back into the pressure-generating chamber 28.

It will be apparent that the downward speed of the intermediate contact 4| will be about the same both during the interruption of high currents as during the interruption of low currents because of the approximate balance of pressure on the two sides of the contact 4|. Following interruption of the circuit through the interrupter, the movable contact I! moves downwardly out of the unit I2 to provide an isolating gap in the circuit. The check valve 21 opens to permit accumulated gas within the pressure-generating chamber 28 to pass therethrough and out of the unit |2 through a vent 14 provided in the contact foot I9. As a result, fresh oil of high dielectric strength is thereby permitted to enter the unit I2 in preparation for the next opening operation. During the closing operation, the movable contact I! moves upwardly to pick up the bumper 46 raising the intermediate contact 4| so that engagement is made between the contacts 22 and 4|, and between the contacts I! and 49 to re-establish the electrical circuit through the interrupter.

Fig. 11 shows a modified type arc-extinguishing unit 1'! of slightly different construction. A modified type of intermediate contact 18 is employed having a pin 19 passing .therethrough and having a flange 88 integrally formed at its lower end. A compression spring 8| is disposed between the bottom plate 82 of the unit 11 and the flange 88. The intermediate contact 18 makes sliding electrical connection with a contact 83, the latter being electrically connected by a conductor 84 to a conducting plate 85 which supports the stationary contact 49. Surrounding the intermediate contact 18 is an insulating cylindrical piston member 86 having a flange 81 integrally formed at its lower end. A compresion spring 88 is disposed about the piston member 88 and has its nular corrugations 89.

The pressure-generating chamber 28 is formed by a plurality of insulating plates 90 having a configuration more clearly shown in Fig. 13. Each plate 90 has apertures 32 formed therein to accommodate the tie rods 29 and also has an enlarged cutout portion 9|. The cutout portions 9| of the several plates 99 align to form the pressuregenerating chamber 28 in which the pressuregenerating are 39 is established between the stationary contact 22 and the intermediate contact 18.

The pressure generated at the pressure-generating are 39 forces oil out of the pressure-generating chamber 28 through the passage 56 through the valve 59 (during high current interruption) and downwardly into the interrupting chamber 51.

In this embodiment of our invention, the interrupting chamber 51 is formed by a plurality of insulating plates having a configuration more clearly shown in Fig. 14. The plates are of four different types. The first type is designated by the reference numeral 92 and is clearly shown by the full lines in Fig. 14. The plate 92 has a cutout portion 93 which forms. a plurality of pockets 94. The plate 92. also has a vent passage 95. The second type of plate used in the'interrupting chamber 51 of Fig. 11 is identical to the plate 92 previouslydescribed but it is inverted so that the vent passage 95 is positioned on the opposite side of the intermediate contact I8. This plate may be designated by the reference numeral 96.

A third type of plate is designated by the reference numeral 9'! and has a cutout portion 98 which'communicates with a widened portion 99, the latter also, in turn, communicating with a restricted portion I99, as more clearly shown in Fig. 14. The fourth type of plate is designated by the reference numeral l 9! and has a configuration substantially the same as the configuration of the insulating plate 92 with the exception that the vent passage 95 is omitted.

The foregoing insulating plates are stacked to form the interrupting chamber 51 in Fig. 11 in the following order: plate 91, plate 96, plate 91, two plates IUI, plate 97, plate 92, plate 9'1, two plates IIII, plate 91, plate 96, plate 91, two plates till and finally bottom insulating plate 82. All of the foregoing plates have apertures 32 provided therein to accommodate the tie rods 29. Also, all of the above-mentioned plates have apertures I92 which align to form a passage through which slidably moves the intermediate contact I8.

The operationpf this embodiment of our invention will now be explained. In the closed circuit position of the interrupter, the electrical circuit therethrough comprises terminal stud 8, contact foot I0, bolt 29, housing 2|, bolt 29, conducting plate 25, stationary contact 22, intermediate contact 78, contact 83, conductor 94, conducting plate 95, stationary contact 49, movable contact I1 through the conducting bridging member I through'the other arc-extinguishing unit 11 in like manner to the other terminal stud l. During the interruption of high amperage currents, the pressure-generating are 39 forms sufiicient pressure within the pressure-generating chamber 28 to open the valve 59 and to force oil downwardly into the interrupting chamber 51, in which the oil flow biases the interrupting are 65 toward the left in the direction of the vents 95. During relatively high instantaneous values of arcing current, that is, during the peak of the alternating-current wave, the cross-sectional area of the interrupting are 95 is too large to permit the oil flow to carry it toward the left into the restricted portions I99 provided in the insulating plates 91. It is only during relatively low instantaneous values of arcing current, that is, near a current zero, when the cross-sectional area of the interrupting arc 65 is sufficiently small to permit the oil flow to carry it toward the left into the restricted portions I99. When this occurs, the interrupting are 65 engages fresh oil disposed in the pockets 94 and is subjected to a deionizing blast of oil as the oil passes out of the interrupting chamber 5'! through the vents 95. Extinction soon follows, and the electrical circuit through the unit 71 is interrupted.

During the interruption of low amperage curents, the pressure generated within the pressuregenerating chamber 28 is not sufiicient to provide an adequate oil fiow to eifect a rapid extinction of the interrupting are 65. In this event, the cylindrical piston member 86, moving downwardly independently of the intermediate contact I8, moves into the piston chamber 42 under the biasing action of the compression spring 88 to displace oil therefrom, which oil flows through the passage 55 to close the valve 49 and to pass downwardly into the interrupting chamber'5'l where extinction of the interrupting are 65 takes place in a manner as previously described.

It will be observed that in this embodiment of our invention, the downward motion of theintermediate contact '58 is not impeded by the piston 86, and consequently the pressure-generating arc 39 is very rapidly drawn. During the closing operation, the bumper I9 picks up the intermediate contact I8 to raise the pin I9 which engages the cylindrical piston member to cause the charging of the latter. It will be observed that the annular corrugations 89 provided on the inner wall of the piston member 89 retains a plentiful supply of oil adjacent to the pressure-generating are 39 as the latter is quickly lengthened by the rapid downward movement of the intermediate contact I8. Consequently, considerable interrupting ability is provided at the pressure-generating arc 39.by the provision of the annular corrugations 89.

Fig. 12 shows a modified type of arc-extinguishing unit generally designated by the reference numeral I55. In this embodiment of our invention, the pressure-generating are 39 is established between a pivotally mounted pressure-generating contact H16, the latter being pivoted at I91 to a bifurcated bracket I98 secured by bolts I99 to the contact foot ID of the unit I95, and. the intermediate contact H9. The left-hand end of the contact I is bifurcated at III and has slots H2 disposed therein through which passes a pin H3 carried by an insulating operating rod II4 biased downwardlyby a compression spring H5. The compression spring I I5 has its upper seat in a recess H6 formed in the contact foot Ill.

The operating rod H9 is engaged by a bumper I9 secured to the bridging member I5 and having a resilient dashpot arrangement, generally designated by the reference numeral I I8, to provide the requisite contact pressure between the contacts I06, H0 and also between the contacts H9 and II. In other words, the compression spring H9 associated with the dashpot H8 provides the requisite contact pressure for the several contacts.

The pressure-generating chamber 28 is formed by the abutting relation of three types of insulating plates. The first type is designated by the reference numeral I2I and is more clearly shown by the full lines in Fig. 15. The second type of plate is herein called a magnetic insert plate I22 and is also shown by the full lines in Fig. 15. Inserted in the insert plate I22 is a U-shaped member I23 composed of a suitable magnetic material, such as iron. On either side of each insert plate I22 is an insulating guard plate I24 and having a configuration identical to the configuration of the magnetic insert plate I22 with the exception that no magnetic insert I23 is employed. Again the function of the insulating guard plates I24 is to protect the insert I23 from the effect of the pressure-generating are 39 as it is magnetically moved laterally within the pressure-generating chamber 28 and to'form substantially V-shaped restricting means 34a.

Preferably an arcing horn I 25 is associated with the intermediate contact III) to facilitate the rightward movement of the are 39. A passage I26 interconnects the pressure-generating chamber 28 with the interrupting chamber 51 of the plate I21 and is more clearly shown by the full lines in Fig. 16. The vent plate I21-has an enlarged cutout portion I28 which vents at I29 to the region exterior of the unit I05. The second type of plate is designated by the reference numeral I30 and has an enlarged cutout portion I3I which communicates with a restricted portion I32, the latter, in turn, communicating with a slightly enlarged region I33. The third type of plate is herein called an insulating pocket plate I34 and is shown by the dotted lines in Fig. 16. The pocket plate I 34 has an enlarged cutout portion I 35 which provides a plurality of pockets I36.

The plates are positioned in the upper portion of the interrupting chamber 51 so that two pocket plates I34 are positioned between two plates I30. The vent plates I21 are positioned between adjacent insulating plates I30.

The lower portion of the interrupting chamber 51 is formed by three types of insulating plates more clearly shown in Figs. 17 and 18. The first type of plate I31 is herein called a magnetic insert plate and is more clearly shown in Fig. 18. This plate has a concave portion I38 to accommodate the operating rod H4 and the dashpot H8. This plate also has a magnetic insert I39 positioned therein. Otherwise, this plate has a configuration identical to that of plate I 30 previously described. Immediately above and below each insert plate I31 is an insulating guard plate I40 having a configuration identical to the insert plate I31. Separating adjacent groups of insert and guard plates I31 and I40 are pocket insulating plates I4I having a configuration identical to the pocket plates I34 previously described with the exception that the plates I 4| have the concave portion I38 removed therefrom. The pocket plates I4I are more clearly shown by the full lines of Fig. 17.

The operation of this embodiment of our invention will now be explained. In the closed circuit position of the interrupter, the electrical circuit therethrough comprises contact foot I0, bracket I08, pin I01, contact I06, intermediate contact H0, and lower movable contact I1. During the opening operation, the bumper I9 and the movable contact I1 move downwardly, thereby permitting the compression spring II5 to force the operating rod II4 downwardly, pivoting the contact I06 in a counterclockwise direction about the pivot I01, thus separating the contact I06 from the intermediate contact III! to establish a pressure-generating are 39. Substantially at the same time that separation of the contacts I06 and H takes place, the movable contact I1 separates from the contact II 0 to draw an interrupting are 65. The reaction of the magnetic inserts I23 0n the pressure-generating are 39 biases the pressure-generating are 39 toward the right into the restriction I 42 provided by the plates I22 and I24. As a result, considerable interrupting ability is possessed by the pressure-generating chamber 28, the arcing horn I25 facilitating the lateral motion of the are 39. The pressure generated at the pressure-generating are 39 forces oil to flow in the direction indicated by the arrows in Fig. 12 to carry the interrupting are 65 toward the vents I 29. Not only is the interrupting are 65 biased toward the vents I29 by the oil flow passing through the passage I26, but also the magnetic inserts I39 bias the interrupting are 65 to the right. Asa result,

the are 65 moves very rapidly to the right having its upper terminal moving along the arcing horn I43 and having its lower terminal run down the side I44 of the movable contact I1. The net result is that the are 65 lengthens at a far greater speed during low instantaneous values of arcing current than the speed of separation of the contacts I1 and H0. The relatively short gap then existing between the contacts I1 and I I0 is then scavenged by the oil fiow moving through the passage I26.

Figs. 19 and 20 illustrate a further embodiment of our invention which is similar to that disclosed in Fig. 11, except that the interrupting chamber I45 is modified to incorporate improved interrupting characteristics as set forth in a patent application by Leon R. Ludwig, Winthrop M. Leeds and Benjamin P. Baker filed November 11, 1942, Serial No. 465,244, now U. S. Patent 2,l06,e69, issued August 27, 1945, and assigned to the assignee of the instant application. This patent also covers some other features of our improved constructions.

More specifically, the interrupting chamber I46 comprises a plurality of suitably formed insulated plates which are of four different types. The first type is designated by the reference numeral I 46 and is herein designated as an orifice plate. This plate has a cutout portion I41 provided therein, as shown more clearly in Fig. 20, and a second opening I48 provided therein which relatively closely surrounds the lower contact I'I. Between adjacently positioned orifice plates I 46 are vent plates generally designated by the reference numeral I99 which comprise two plates I50, I50a disposed in the same horizontal plane and illustrated more clearly in Fig. 20.

Between the two vent plates I49 are disposed inlet plates designated by the reference numeral I5I and having a configuration more clearly shown in Fig. 20, wherein the cutout portion I41 communicates with an enlarged inlet portion I52. Adjacent the lower end of the modified interrupting structure are a plurality of plates which form recesses I53 adjacent the vertical path of movement of the movable contact I1.

The operation of this embodiment of our invention is the same as that previously described in connection with Fig. 11, except that in the interrupting chamber I46, the fluid passes inwardly toward the interrupting are 65 through the inlet portions I52 after having passed downwardly through the passage 56 and through the valve 59. After the inwardly flowing fluid has struck the interrupting are 65, it passes through the openings I48 provided by the orifice plates I48 in intimate contact with the interrupting are 65 to exhaust out of the arc extinguishing unit through the vents I54 as indicated by the arrows I55 in Fig. 20.

The interrupting structure has been found to give excellent interrupting ability with very low dissipation of are energy and a corresponding low arc voltage.

Certain broad features of our invention are described and broadly claimed in a patent application filed September 18, 1942, Serial No. 458,- 778, by Winthrop M. Leeds and Benjamin P. Baker, now United States Patent 2,372,589, issued March 27, 1945, and a patent application filed January 9, 1943, Serial No. 471,847, new U. S. Patent 2,412,857, issued December 17, 1946, by Benjamin P. Baker, all of the foregoing applications being assigned to the assignee of the instant application.

From the above disclosure, it will be apparent that we have provided an improved circuit interrupter which utilizes the pressure created at a pressure-generating arc to effect the extinction of the interrupting arc during relatively high amperage currents, and which utilizes a novel piston arrangement to efiect the extinction of the interrupting arc during the interrupting of low currents when the pressure generated at the pressure-generating arc is not sufiicient to provide an adequate oil flow. The piston may be an integral portion of the intermediate contact, or if may be independently movable therefrom to enable the pressure-generating arc to be more rapidly lengthened. We have also disclosed how the pressure-generating arc may be magnetically moved laterally to not only increase the pressure formed thereat, but also to increase the interrupting ability in the pressure-generating chamber.

Although we have shown and described specific structures, it is to be clearly understood that the same are 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.

We claim as our invention:

1. In a circuit interruptor, an arc-extinguishing unit, a substantially enclosed first chamber disposed adjacent one end of the unit, a piston chamber disposed intermediate the ends of the unit, an interrupting chamber disposed adjacent the other end of the unit, means comprising an intermediate contact for establishing a pressuregenerating arc within the first chamber, means for establishing an interrupting are within the interrupting chamber, and piston means associated with the intermediate contact and movable into the piston chamber during the opening operation of the interrupter, the piston means being charged by closing movement of the intermediate contact but independently movable therefrom during the opening operation of the interrupter.

2. In a circuit interrupter, an arc-extinguishing unit, a substantially enclosed first chamber disposed adjacent one end of the unit, a piston chamber disposed intermediate the ends of the unit, an interrupting chamber disposed adjacent the other end of the unit, means comprising an intermediate contact for establishing a pressuregenerating are within the first chamber, means for establishing an interrupting are within the interrupting chamber, and piston means associated with the intermediate contact and movable into the piston chamber during the opening operation of the interrupter, first passage means interconnecting the first chamber and the interrupting chamber and bypassing the piston chamber, and second passage means interconnecting the piston chamber and the interrupting chamber.

3. In a circuit interrupter, an arc-extinguishing unit, a substantially enclosed first chamber disposed adjacent one end of the unit, a piston chamber disposed intermediate the ends of the unit, an interrupting chamber disposed adjacent the other end of the unit, means comprising an intermediate contact for establishing a pressuregenerating are within the first chamber, means for establishing'an interrupting are within the interrupting chamber, piston means associated with the intermediate contact and movable into the piston chamber during the opening operation of the interrupter, first passage means interconnecting the first chamber and the interrupting chamber and bypassing the piston chamber, second passage means interconnecting the piston chamber and the interrupting chamber, and valve means disposed in the first passage means.

4. In a circuit interrupter, an arc-extinguish ing unit, a pressure-generating chamber disposed adjacent one end of the unit, substantially V-shaped restricting means disposed within the pressure-generating chamber, an interrupting chamber disposed adjacent the other end of the unit, means comprising a pivotally operable movable contact cooperable with an intermediate contact to establish a pressure-generating are within the pressure-generating chamber, a movable contact cooperable with the intermediate contact to establish an interrupting are within the interrupting chamber, and means for magnetically moving the pressure-generating arc laterally into the restricting means to increase the pressure formed thereat.

5. In a circuit interrupter, an arc-extinguishing unit, a substantially enclosed first chamber disposed adjacent one end of the unit, a piston chamber disposed intermediate the ends of the unit, an interrupting chamber disposed adjacent the other end of the unit, means comprising an intermediate contact for establishing a pressure-generating are within the first chamber, means for establishing an interrupting are within the interrupting chamber, and piston means comprising an independently movable cylinder surrounding the intermediate contact and movable into the piston chamber during the opening operation of the interrupter, the cylinder having one or more annular corrugations to be moved adjacent the pressure-generating arc.

6. In a circuit interrupter of the liquid break type, an arc extinguishing unit, a pressure-generating chamber disposed adjacent one end of the unit, a piston chamber positioned intermediate the ends of the unit, an interrupting chamber disposed adjacent the other end of the unit, a relatively stationary pressure-generating contact disposed adjacent the said one end of the unit within the pressure-generating chamber, a relatively stationary interrupting contact disposed intermediate the ends of the unit within the interrupting chamber, two movable contacts movable in the same direction and substantially simultaneously separable from the two relatively stationary contacts to establish a pressure-generating arc within the pressure-generating chamber and an interrupting are within the interrupting chamber, at least a portion of the movable contact separable from the relatively stationary pressure-generating contact acting as a piston by moving into the piston chamber, and passage means connecting the piston chamber with the interrupting chamber, and other passage means bypassing the piston chamber and connecting the pressure-generating chamber with the interrupting chamber.

7. In a circuit interrupter of the liquid break type, an arc extinguishing unit, a pressure-generating chamber disposed adjacent one end of the unit, a piston chamber positioned intermediate the ends of the unit, an interrupting chamber disposed adjacent the other end of the unit, a relatively stationary pressure-generating contact disposed adjacent the said one end of the unit within the pressure-generating chamber, a relatively stationary interrupting contact disposed intermediate the ends of the unit within the interrupting chamber, two movable contacts movable in the same direction and substantially simultaneously separable from the two relatively stationary contacts to establish a pressure-generating are within the pressure-generating chamber and an interrupting are within the interrupting chamber, at least a portion of the movable contact separable from the relatively stationary pressure-generating contact acting as a piston by moving into the piston chamber, passage means connecting the piston chamber With the interrupting chamber, other passage means bypassing the piston chamber and connecting the pressure-generating chamber with the interrupting chamber, and valve means positioned within the said other passage means to prevent circulation of liquid back into the pressure-generating chamber during low current interruption.

8. A circuit interrupter including an arcex tinguishing unit, means defining a pressure-generating chamber disposed adjacent one end of the unit, substantially V-shaped restricting means disposed Within the pressure-generating chamber, means defining an interrupting chamber disposed adjacent the other end of the unit, means estab lishing a pressure-generating are within the pressure-generating chamber, means establishing an interrupting are within the interrupting chamber, and means for magnetically moving the pressure-generating arc laterally into the restricting means to increase the pressure formed thereat.

9. A circuit interrupter including an arc extinguishing unit, a substantially enclosed first chamber disposed adjacent one end of the unit, a piston chamber disposed intermediate the ends of the unit, an interrupting chamber disposed adjacent the other end of the unit, means comprising an intermediate contact for establishing a pressure-generating are within the first chamber, means establishing an interrupting arc within the interrupting chamber, piston means associated With the intermediate contact and movable into the piston chamber during the opening operation of the interrupter, first passage means interconnecting the first chamber and the interrupting chamber and by-passing the piston chamber, second passage means interconnecting the piston chamber and the interrupting chamber, and means for magnetically moving the pressuregenerating arc laterally to increase the pressure formed thereat.

10. A circuit interrupter including an are extinguishing unit, a substantially enclosed first chamber disposed adjacent one end of the unit, a piston chamber disposed intermediate the ends of the unit, an interrupting chamber disposed adjacent the other end of the unit, means comprising an intermediate contact for establishing a pressure-generating are within the first chamber, means for establishing an interrupting are within the interrupting chamber, piston means associated with the intermediate contact and in cluding an independently movable cylinder surrounding the intermediate contact and movable within the piston chamber during the opening operation of the interrupter, first passage means interconnecting the first chamber and the interrupting chamber and by-passing the piston chamber, and second passage means interconnecting the piston chamber and the interruptin chamber.

11. A circuit interrupter including an are extinguishing unit, means defining a pressure-generating chamber disposed adjacent one end of the unit, substantially V-shaped restricting means disposed within the pressure-generating chamber, one or more vent passages disposed along the substantially V-shaped restricting means, means defining an interrupting chamber disposed adjacent the other end of the unit, means establishing a pressure-generating are within the pressure-generating chamber, means establishing an interrupting arc within the interrupting cham ber, means for magnetically moving the pressure-generating arc laterally into the restricting means to increase the pressure formed thereat, and fluid passage means interconnecting the pressure-generating and interrupting chambers and including said one or more vent passages.

BENJAMIN P. BAKER. WINTHROP M. LEEDS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,151,551 Ishiwata 1- Mar. 21, 1939 2,158,846 Balachowsky May 16, 1939 2,271,989 Prince Feb. 3, 1942 2,292,547 Sadler 1. Aug. 11, 1942 2,372,589 Leeds et al. Mar. 27, 1945 2,406,469 Ludwig et al. Aug. 27, 1946

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