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Publication numberUS2673272 A
Publication typeGrant
Publication dateMar 23, 1954
Filing dateMay 15, 1951
Priority dateMay 15, 1951
Publication numberUS 2673272 A, US 2673272A, US-A-2673272, US2673272 A, US2673272A
InventorsCushing George B
Original AssigneeWestinghouse Electric Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Circuit interrupter
US 2673272 A
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Description  (OCR text may contain errors)

March 1954 G. B. CUSHING CIRCUIT INTERRUPTER 2 Sheets-Sheet 1 Filed May 15 1951 Fig.3.

Insulation Fig.l.

INVENTOR George B.Cushin G EJ WITNESSES:

March 23, 1954 B cusH N 2,673,272

CIRCUIT INTERRUFTER Filed May 15, 1951 2 Sheets-Sheet 2 Insulation A f A WITNESSES: INVENTOR 54 George B.Cu shing.

Patented Mar. 23, 1954 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER George B. Cushing, Turtle Creek, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 15, 1951, Serial No. 226,507

25 Claims. 1

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 fluid blast type of circuit interrupter which will be more easily inspected, and which will be more economical to manufacture and to service.

'A further object is to provide an improved circuit interrupter which will have reduced dimensions, and yet despite such reduced size, will have as equally effective operating characteristics as interrupters of the same type heretofore manufactured.

Still a further object is to provide an improved arc-extinguishing structure, the walls of which are of cylindrical form in which one or more venting inserts are provided. Preferably such inserts are mounted in apertures provided in the walls of the casingso that the insert may extend internally across the casing.

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

Figure 1 is a side elevational view, partially in vertical section, of an improved arc-extinguishing unit embodying my invention, the contact structure being shown in the partially open circuit position;

Fig. 2 is an end elevational view of the insert employed in the extinguishing unit of Fig. 1;

Fig. 3 is a side elevational view of the insert pictured in Fi 2;

Fig. 4 is a plan view in section, taken along the line IV-IV of Fig. 3;

Fig. 5 is a side elevational view of a .complete circuit interrupter, the tank being partly broken away to show the internal construction thereof, and the contact structure being shown in the closed circuit position; and

Fig. 6 is a plan view in section taken along the line VI-VI of Fig. 1.

Referring to the drawings, and .more particularly to Fig. 1 thereof, the reference numeral l designates a terminal bushing extending downwardly from the cover 2 of a tank 3, with particular attention being directed to Fig. 5, the latter showing a complete circuit interrupter of the type considered.

Extending interiorly through the terminal bushing I is a terminal stud 4 which is exteriorly threaded. The lower end of the terminal stud 4 is threadedly secured to, and clamped by, a contact foot :5, bolts 6 being employed to clamp the contact foot 5 to the lower end of the terminal stud 4.

Preferably, the contact foot 5 is an integral part of a cupshaped top dome casting I, the lower end of which is internally threaded, as at 8, to fixedly maintain in position an insulating cylindrical casing ID.

A relatively stationary pressure-generating contact H is pivotally mounted interiorly within the top dome casting I in any suitable manner, and cooperates with an intermediate contact H. to establish a pressure-generating arc l3 Within a pressure-generating chamber, generally designated by the reference numeral M.

The intermediate contact I2 is spring-biased downwardly, in the opening direction, and is moved upwardly in the closing direction against the spring pressure by a lower movable rodshaped interrupting contact I6. Preferably, the interrupting contact I6 is fixed to the end of a conducting bridging member I! (Fig. 5) which is vertically actuated in its opening and closing movements by an insulating operating or lift rod It. The operating rod l8 may be actuated by any suitable operating mechanism, which forms no part of my invention.

It will be observed that the diametrical opposite walls of the casing II] have mounting apertures [9 provided therein, within which is placed and. mounted a multi-orifice venting insert, generally designated by the reference numeral 20. The multi-orifice venting insert 20 is preferably molded out of any suitable insulating molding material so that it is an integral unit. Figs. 2-4 more clearly show the construction of the unitary multi-orifice venting insert 20. It will be noted that the venting insert 20 has two pairs of venting passages 21, which extend from a central passage 22 to the region exteriorly of the extinguishing unit 23, as more clearly shown in Figs. 1 and Also the venting insert 20 has a pair of inlet passages 24 which communicate between the central passage 22 and the interior 25 of the extinguishing unit 23. .Fig. 6 may be referred to in this connection.

Preferably, the venting insert 20 has a pair of ring-shaped end portions 26 which fit within the mounting apertures 19 of the casing H). The outer ends of the venting passages 2| extend laterally beyond the ring-shaped end portions 26 to cooperate with aretainer ring 21, more clearly shown in Figs. 1 and 6. Machine screws 28 fixedly secure the retainer ring 21 in position, and their interior ends 28a preferably main,-

tain in position a centrally apertured lower closure plate 29, through which the lower movable interrupting contact l6 moves during the opening and closing operations of the interrupter.

The operation of my improved arc-extinguishing unit will now be described. During the opening operation, suitable mechanism, responsive either to manual operation or to the existence of overload conditions existing in the circuit controlled by the interrupter, causes downward opening motion of the insulating lift rod l8 (Fig.

The downward opening motion of the lift rod [8 causes corresponding downward opening motion of the conducting bridging member H and the two interrupting contacts I6 disposed at the outer edges of the bridging member I1.

Referring to Fig. 1, the downward opening motion of the rod-shaped interrupting contact 16 will first permit the contact pressure spring, not shown, associated with the pressure-generating contact 5 l to permit slight downward travel of the pressure-generating contact ll. Further downward opening travel of the interrupting contact IE will be followed by the intermediate contact I2 due to the accelerating spring pressure, not shown, associated therewith. The consequent separation between the pressure-generating and intermediate contacts l I, [2 will cause the establishment of a pressure-generating arc l3, as shown in Fig. 1.

Continued downward opening motion of the interrupting contact IE will result in a separation between the intermediate and interrupting contacts [2, Hi, the intermediate contact 12 having been halted in its downward opening travel by a suitably disposed stop, not shown. This results in the establishment of an interrupting are 30 between the intermediate and interrupting contacts l2, H5 through the centrally disposed arcing passage 22 of the venting insert 20, as shown more clearly in Fig. l.

' Since liquid, such as oil 31, fills the tank 3 to the level 32 (Fig. 5) oil will completely fill the extinguishing unit 23, and the establishment of a pressure-generating arc l3 will generate pressure within the pressure-generating chamber 14 internally within the casing in. This pressure will be communicated downwardly through the region and will act through the inlet passages 24 in the manner indicated by the arrows of Figs. 1, 3, 4 and 6. Also oil will be forced downwardly through the top orifice 33 of the insert 20, and upwardly through the bottom orifice 34 of the insert 20, as more clearly shown in Fig. 1.

The orifices 33 and 34, together with the intermediate orifices 35, 36, the latter being disposed intermediate the venting passages 2| and the central inlet passage 24, all serve to direct fluid, in this instance oil, through the central arc passage 22 and into engagement with the interrupting are 30.

Following contact with the interrupting arc .30,.such liquid passes out of casing l0 through the two pairs of exhaust passages 2|, as indi- 'cated by the arrows in Figs. 1, 3, 4 and 6. Deionization and extinction of the interrupting are soon follows, and the circuit is interrupted. The interrupting contact [6 moves downwardly with the cross-bar l1 and lift rod l8 to the dotted line open circuit position, as indicated by the reference numeral 31 of Fig. 5, thereby introducing two serially related isolating gaps in the circuit. i

During the closing operation, it is merely nec' essary to cause upward movement of the operating rod [8, which raises the cross-bar l1 and the interrupting contacts [6. The latter enter the apertures 38 provided in the extinguishing units 23, pass along the arcing passages 22, pick up the intermediate contacts 12 and raise the latter into contacting engagement with the pressure-generating contacts II against the spring pressure associated with the intermediate contacts 12. The circuit is then closed. Obviously, in the closed circuit position of the interrupter the electrical circuit therethrough includes the terminal stud 4, extending through the left-hand terminal bushing I, the contact foot 5, pressuregenerating contact ll, intermediate contact 12, lower interrupting contact 16, conducting bridging member I! and through the right-hand extinguishing unit 23 in similar fashion to the right-hand terminal bushing 39 (Fig. 5).

Referring to Fig. 5, it will be observed that I show modified arc-extinguishing units 40 serially connected, and each unit 40 employing a pair of venting inserts 20, the latter being angularly displaced from each other, as shown in Fig. 5, to thereby insure a more uniform dissemination of the exhaust arc gases exteriorly of the extinguishing units 40. In other words, in order to prevent a possible external fiashover, it is desirable to prevent the exhause arc gases, which are of a low dielectric strength, from being too concentrated at any one point. Therefore, by angularly displacing the position of the venting inserts 20, as shown in Fig. 5, the arc gases 1 are more uniformly disseminated, and yet advantage may be takenof my improved insert construction for interrupting the higher voltages, where a longer length of interrupting are 30 may have to be interrupted.

Preferably, where only two venting inserts are employed for each extinguishing unit, the inserts are angularly disposed approximately degrees so that the vertical spacing between axes of the inserts can be less than the diameter of the end portions 26 without interference, and orifices can be spaced at regular intervals in the interrupting gap. Also, in addition to the retainer ring 21 for the lower venting insert 20, an additional retainer ring 4| may be employed on the top side of the upper venting insert 20, as shown in Fig. 5.

Heretofore, the multi-orifice structure associated with the interrupting arc 30 has been formed by the contiguous superpositioning of a plurality of fibre insulating plates, suitably configured. Reference may be had to United States Patent 2,467,760, issued April 19, 1949 to Leon R. Ludwig, Benjamin P. Baker and Winthrop M. Leeds, and assigned to the assignee of the instant application for a description of the general type of plates which were used.

Common practice, such as disclosed in this patent, employed fibre plates or I 6 inch thick, in quantity exceeding 30. These, together with special fibre plates, end plates and castings were bolted into a unit with insulated tie rods. Although such a construction has proved to be highly effective in extinguishing the arcs, yet it is obvious that the manufacturing cost is appreciable because large areas of the original fibre must be removed to provide oil channels, openings for tie rods, vent passages and clearance for the contacts. Moreover, a fibre Wall must be maintained between the high pressure region within the arcextinguishing stackand theoil external to the age-ra es stack; otherwise leakage will upset the controlled oil now. However, because of its laminar construction, no longitudinal tensile strength can be derived from this wall, and tie-rods must be provided for this function. It has generally been necessary to have an extremely large number of components which must be carefully manufactured and assembled. Replacement of the orifices can be accomplished only by complete disassembly, and the stack length is variable according to the moisture content of the fibre plates.

The design which I propose, and which is described above, is a multi-orifice structure em bodied in a heavy walled, high strength, insulating tube. The venting means 20, which I provide in the region of the interrupting gap 30, is maintained in position by a tubular retainer 21, which is slid on the bottom of the interrupter and attached by screws 28. Th cooperation between the upper edge of the retainer ring 21 and the lower side 42 (Fig. l) of the lower venting passage 2l prevents shifting and rotation of the venting means 20 after installation.

This multi-orifice venting insert '20, placed in a tube in the disclosed manner, possesses several advantages. First, the tube It) can be designed to contain the internal pressures, and yet can be relatively thin-walled because of its favorable circular shape. So designed, it also will withstand tensile stresses along its axis, eliminating any need for tie-rods, which were used in the construction set out in Patent 2,467,760. Additional space will accordingly be available for internal oil flow.

The venting means 20, which I have illustrated, makes possible the incorporation of multi-flow action in a tubular structure with several advantages. It is extremely simple, being a single molded insert installed in holes drilled on the diameter of tube I yet this simplicity incorporates all of the inlet channels and vent passages, commonly supplied in the interrupting gap of a multi-flow type of interrupter, as set out in the aforesaid patent.

There is little opportunity for leakage, the intersection of the tube [0 and venting means 20 being a simple curve which may, if desired, be sealed with an O ring type gasket. The tubular construction of the walls encasing th venting passages 2| in the venting insert 20 provides considerable resistance to pressures within chamber 25.

Internal forces within chamber 25 tending to expel the venting insert 20 from the arc-extinguishing unit 23 are balanced, giving zero net horizonta1 force. Replacement of the venting means 20 entails simply removal of retainer ring 21, attached with screws 28 and a complete new set of interrupting orifices 33-36, provided by a new insert 20, will return a heavily used extinguishing unit 23 to good as new condition. Functionally, space not required for venting is available as large cross-sectional oil flow channels; and the elimination of the tie-rows, previously'used, will permit the entire arc-extinguishing unit to have smaller external dimensions.

Where higher voltage applications require additional multi-flow orifices, the venting means 20 can be installed in multiple, as indicated in Fig. 5, successive units 20 being oriented on other diameters around tube II). By this means, the vented gas can be distributed around the interrupter to reduce the hazard of external flashover. Also spacing between adjacent venting means 7.0 can be smaller than the diameter of the ends 6 of these components. The distribution of vented gas would be particularly desirable in a low oil content type of breaker where the gases are restricted by the closely encasing tubing.

The venting means 20 could also be applied to an impulse type of interrupter, where a piston substitutes for the pressure-generating arc l3 in raising the internal pressure of the interrupter and thereby causing oil flow. Thus certain features described in my invention make it particularly well adapted to low oil content breakers of either the self-generated gas blast or impulse type.

The foregoing description of two embodiments of my invention show how I have constructed a multi-fiow type of interrupter in a tube with means of venting the tubular constructed interrupter to give multi-fiow characteristics. Also my improved interrupter gives improved interrupting performance by providing larger section oil channels with no increase in over-all size. The foregoing construction permits easy replacement of interrupting orifices, and the inserts can readily be formed of a suitable molding material.

Although I have 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 therein by those skilled in the art, without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. A circuit interrupter including a casing, means establishing an arc within the casing, interrupting passage structure for extinguishing the are, a venting insert having an exhaust passage constituting at least a portion of said interrupting passage structure and exhausting fluid from the arc away from th interrupting passage structure and out of the casing, the side Wall of the casing having an aperture to assist in supporting the insert, and the insert being laterally removable from the side wall of the casing.

2. A circuit interrupter including a casing, a pair of mounting apertures provided diametrically in the side walls of the casing, means for establishing an arc within the casing, interrupting passage structure for extinguishing the arc, a venting insert having exhaust passages therein constituting at least a portion of said interrupting passage structure and exhausting fiuid from the arc and out of the casing, the venting insert being mounted in the apertures and extending diametrically across the casing, and the venting insert being laterally removable from the side wall of the casing.

3. A circuit interrupter including a casing, means establishing an are within the casing, interrupting passage structure for extinguishing the arc, a plurality of venting inserts having exhaust passages and constituting at least a portion of said interrupting passage structure, each venting insert exhausting fluid from the arc out of the casing, a pair of apertures provided in the side wall of the casing angularly displaced to mount the venting inserts, and each venting insert being laterally removable from the side Wall.

of the casing.

4. A circuit interrupter of the liquid break type including a tubular casing, means for establishing a pressure-generating arc and a serially related interrupting are within the casing, the side walls of the casing adjacent the interrupting are having apertures provided therein, and a venting insert laterally removable from the side wall.

of the casing extending between the apertures internally across the casing.

. '5. A circuit interrupter of the liquid break type including a tubular casing, means for establishing a pressure-generating arc and a serially related interrupting are within the casing, the side walls of the casing adjacent the interrupting are having apertures provided therein, a plurality of venting inserts laterally removable from the side wall of the casing extending between the apertures internally across the casing, and each insert being angularly displaced with respect to the adjacently disposed insert to disseminate the ex haust arc gases.

6. A circuit interrupter including a casing, means establishing an are within the casing, a multi-orifice insert having one or more exhaust passages therein for exhausting fluid away from the arc and out of the casing, the side wall of the casing having an aperture to assist in supporting the multi-orifice insert, and the multi-orifice insert being laterally removable from the side wall of the casing.

7. A circuit interrupter including a pressure chamber, a longitudinal casing defining at least a part of said pressure chamber, means for estab lishing an are within the longitudinal casing, a pair of mounting apertures provided diametrically in the side walls of the casing, a multi-crifice insert having one or more exhaust passages therein for exhausting fluid away from the are and out of the casing, the multi-orifice insert extending interiorly across the casing between said apertures, and the multi-orifice insert being laterally removable from the side wall of the casing.

8. A circuit interrupter including a cylindrical casing, means establishing an are within the casing generating pressure therein, a plurality of multi-orifice inserts laterally removable from the side wall of the casing, the side walls of the casing having apertures provided therein so that the multi-orifice inserts may extend internally across the casing, and each multi-orifice insert being angularly displaced with respect to the adjacently disposed multi-orifice insert to disseminate the exhaust arc gases.

9. A circuit interrupter of the liquid break type including a. tubular casing, means for establishing a pressure-generating arc and a serially related interrupting are within the casing, the side walls of the adjacent the interrupting are having apertures provided therein, and a multiorifice insert extending between the apertures internally across the casing and laterally removable from the side wall of the casing.

10. A circuit interrupter of the liquid break type including a tubular casing, means for establishing a pressure-generating are and a serially related interrupting arc within the casing, the walls of the casing adj acent the interrupting are having apertures provided therein, a plurality of laterally removable multi-orifice inserts extending between the apertures internally across the casing, and each multi-orifice insert being angularly displaced with respect to the adjacently disposed multi-orifice insert to disseminate the exhaust arc gases.

11. A circuit interrupter including a cylindrical casing, means including a movable contact for establishing an are within the casing generating pressure therein, a removable venting insert having at least a pair of opposed exhaust passages and one or more inlet passages provided therein, said insert having a centrally-disposed arc passage to accommodate the movable contact, and the walls of the casing having apertures provided therein so that the insert may extend internally across the casing with the opposed exhaust passages exhausting through the apertures.

12. A circuit interrupter including a pressure chamber, a longitudinal casing defining at least part of said pressure chamber, apertures provided diametrically in the walls of the casing, a removable venting insert extending internally or the casing between the apertures, and said venting insert having at least a pair of opposed exhaust passages provided therein to exhaust in substantially opposite directions out of the apertures.

13. A circuit interrupter including a cylindrical casing, means establishing an are within the casing generating pressure therein, a plurality of each insert having at least a pair of opposed exhaust passages provided therein, the exhaust passages exhausting in substantially opposite directions out through the apertures, and eachinsert being angularly displaced with respect to the adjacently disposed removable insert to disseminate the exhaust arc gases.

14. ,A circuit interrupter of the liquid break type including a tubular casing, means for establishing a pressure-generating arc and a serially related interrupting arc within the casing, the walls of the casing adjacent the interrupting are having apertures provided therein, a removable venting insert having at least a pair of exhaust passages provided therein extending between the apertures internally across the casing, and the exhaust passages exhausting in substantially opposite directions out through the apertures.

15. A circuit interrupter including a cylindrical casing, means including a rod-shaped movable contact for establishing an arc within the casing generating pressure therein, a removable vent-' ing insert having a centrally disposed passage provided therein for accommodating movement of the rod-shaped contact, said venting insert also having one or more exhaust passages and at least a pair of inlet passages, the walls of the casing having apertures provided therein so that the venting insert may extend internally across the casing, and the exhaust passages exhausting in substantially opposite directions out through the apertures.

16. A circuit interrupter including a cylindrical effect the latters extinction, a removable vent-. ing insert having a centrally disposed passage.

for accommodating motion of the movable interrupting contact, said venting insert having at least a pair of opposed exhaust passages and at least a pair of cooperating inlet passages, and the walls of the casing having apertures provided therein so that the venting insert may extend internally across the casing.

17. A circuit interrupter of the liquid breal i' type including an arc-extinguishing imit immersed in liquid, the unit including a cylindrical casing, contact means including a rod-shaped. movable interrupting contact for establishing a pressure-generating arc and a serially related interrupting are within the casing, a removable venting insert having a centrally disposed passage therein to: accommodate motion of the rod" shaped movable interrupting contact, said venting insert also having at least a pair of opposed exhaust passages and at least a pair of cooperating inlet passages, and the walls of the casing having apertures provided therein so that the insert may extend internally across the casing.

18. A circuit interrupter including a casing, means establishing an arc with-in the casing, a multi-orifice insert having one or more exhaust passages therein for exhausting fluid away from the arc and out of the casing, the side wall of the casing having an aperture engaged by the multi-orifice insert to assist in supporting the multi-orifice insert, the multi-orifice insert being laterally removable as a unit from the side wall of the casing, and a space on each side of the multi-orifice insert between the insert and the inside wall of the casing.

19. A circuit interrupter including a casing, means including a rod-shaped contact movable longitudinally of the casing for establishing an are within the casing, a multi-orifice insert having one or more exhaust passages therein for exhausting fluid away from the are and out of the casing, said multi-orifice insert having an arc passage extending longitudinally of the casing and in which the movable rod-shaped contact moves, the side wall of the casing having an aperture to assist in supporting the multi-orii'lce insert, the multi-orifice insert being laterally removable from the side wall of the casing, a space on each side of the multi-orifice insert between the insert and the inside wall of the casing, and one or more inlet passages leading from the space in the casing to the arc passage.

20. A circuit interrupter including a cylindrical casing, means establishing an are within the cylindrical casing, a multi-orifice insert having one or more exhaust passages therein extending out of the casing for exhausting fluid away from the arc and out of the casing, the side wall of the cylindrical casing having an aperture to assist in supporting the multi-orifice insert, and the multi-orifice insert including its one or more exhaust passages having transverse dimensions no greater than the dimensions of the aperture and being laterally removable from the side wall of the casing through the aperture.

21. A circuit interrupter including a cylindrical casing of insulating material, means establishing an arc within the cylindrical casing longitudinally thereof, a multi-orifice insert of insulating material having one or more exhaust passages therein for exhausting fluid away from the arc and laterally out of the cylindrical casing, the side wall of the cylindrical casing having an aperture to assist in supporting the multi-orifice insert and through which the fluid exhausts, the multi-orifice insert being laterally removable from the side wall of the cylindrical casing, and a space having the shape of a segment of a circle on each side of the multi-orifice insert between the insert and the inside wall of the cylindrical casing.

22. A circuit interrupter including a casing, means including a movable rod-shaped contact for establishing an are within the casing, a multiorifice insert having one or more exhaust passages therein for exhausting fluid away from the arc and out of the casing, said multi-orifice insert having a central arc passage in which the movable rod-shaped contact moves, the side wall of the casing having an aperture into which one end of the multi-oriiice insert extends to assist in supporting the multi-orifice insert, said rodshaped contact being movable to a position entirely out of the multi-orifice insert, and the multi-orifice insert then being laterally removable from the side wall of the casing through said aperture.

23. A circuit interrupter including a pressure chamber, a longitudinal casing defining at least part of said pressure chamber, apertures provided diametrically in the walls of the casing, a removable venting insert extending internally of the casing between the apertures, said venting insert having at least a pair of opposed exhaust passages provided therein to exhaust in substantially opposite directions out of the apertures, the whole venting insert which extends between the two apertures being laterally removable from the side wall of the casing through one of the apertures, and a retaining means disposed externally of the casin and engaging a portion of the venting insert to assist in retaining the same in a fixed position in the casing.

24:. A circuit interrupter including a, casing, means establishing an are within the casing, a mu1tiorifice insert having one or more exhaust passages therein for exhausting iiuid away from the arc and out of the casing, the side wall of the casing having an aperture to assist in supporting the multi-orifice insert, the multi-orifice insert being laterally removable from the side wall of the casing through the aperture, and a retaining member disposed externally of the casing and engaging a portion of the multi-orifice insert to assist in retaining the same in a fixed position in the casing.

25. A circuit interrupter including a casing, means including a movable rod-shaped contact for establishing an are within the casing, a multiorifice insert having one or more exhaust passages therein for exhausting fluid away from the arc and out of the casing, said multi-orifice insert having a central arc passage through which the movable rod-shaped contact moves, the side wall of the casing having an aperture to assist in supporting the multi-orifice insert, the multiorifice insert being laterally removable from the side wall of the casing, and at least one end of the central arc passage being relatively open during the are drawing process to permit fluid in the casing adjacent the multi-orifice insert to flow into the arc passage.

GEORGE B. (BUSHING.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,470,611 Friedrich May 17, 1949 2,477,837 Strom Aug. 2, 1942 FOREIGN PATENTS Number Country Date 450,405 Great Britain July 16, 1936

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2470611 *Jan 25, 1947May 17, 1949Westinghouse Electric CorpCircuit interrupter
US2477837 *Aug 25, 1944Aug 2, 1949Westinghouse Electric CorpCircuit interrupter
GB450405A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2821608 *Dec 8, 1954Jan 28, 1958Westinghouse Electric CorpCircuit interrupters
US2900478 *Mar 27, 1956Aug 18, 1959Westinghouse Electric CorpCircuit interrupter
US4665286 *Mar 3, 1986May 12, 1987Emerson Electric Co.Motor starting and automatic reversing switch
Classifications
U.S. Classification218/115, 200/306
International ClassificationH01H33/70, H01H33/75
Cooperative ClassificationH01H33/75
European ClassificationH01H33/75