US2421236A

US2421236A - Electric circuit interrupter

Info

Publication number: US2421236A
Application number: US492691A
Authority: US
Inventors: Ralph S Bennett
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1943-06-29
Filing date: 1943-06-29
Publication date: 1947-05-27
Anticipated expiration: 1964-05-27

Description

y 1947. R. s. BENNETT ELECTRIC CIRCUIT INTERRUPTER Filed June 29, 1943 2 Sheets-Sheet l Inventor Ralph S. Bennett,

u A I 1K I I I I I I I I r I I I I I I I I! His Attorney.

y 1947- Rls. BENNETT 2,421,236

ELECTRIC CIRCUIT INTERRUPTER Filed June 29, 1943 2 Sheets-'Shet 2 F7 .6. v. ,54 7/ I Invento%-:

Ralph S. Bennett,

y )VM 6? ,J AAQQ I Hi5 Attorne \mw, partly in section, of the Patented May 27, 194"! ELECTRIC CIRCUIT INTERRUPTER- Ralph S. Bennett, Pittsfield,

General Electric Company,

New Yor':

Mass, assignor to a corporation of Application June 29, 1943, Serial No. 492,691

Claims. 1

My invention relates to electric circuit interrupters and. more particularly to circuit interrupters of the rluid blast tym wherein pressure is utilized to effect a blast of arc-extinguishing or insulating liquid through a break in the cl"- cuit to be interrupted. Specifically, my invention is an improvement on U. S. Letters Patent 2,049,318, Prince, granted July 28, 1936, and assigned to the same assignee as the present application.

It is an object of my invention to provide a new andimproved fluid blast circuit interrupting means.

It is another object of my invention to provide a fuse cut out type of circuit interrupting device operating on the oil blast principle in which two arcs in series are produced substantially simultaneously so that the oil blast produced may become effective before the current and pressure have increased to dangerously high values.

Still. another object of my invention is to provide a fuse cut out typ of circuit interrupting device operating on the oil blast principle in which two arcs in series are produced substantially simultaneously upon the blowing of a single fusible element.

Further objects and advantages of my invention will become apparent as the following desorlption proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of my invention reference may be had to the accompanying drawings in which Fig.1 is an elevational view, partly in section, of a circuit interrupting device embodying my invention; Fig. 2 is a top circuit interrupter Fig. 1 with the cover of the casing removed; Fig. 3 is a side elevational view. partly in section, of a portion of the fuse carrier of Fig. 1; Figs. 4 and 5 the portion of the fuse carrier shown in Fig. 3, and Fig. 6 illustrates a modification of my invention.

Although my invention may have application generally in connection with fluid blast circuit interrupters, I have chosen to illustrate it specifically as applied to the well known form of oilfilled fuse cut out disclosed in United States Patents 1,195,790, 1,203,316, and 1,248,090.

As shown in the drawings the oil fuse cutout embodying my invention and generally indicated at H! comprises a cyindrical container or tank steel so as to be suflill, preferably formed of are exploded perspective views of ciently strong to withstand the pressures ge. ated therein under certain conditions. i is provided with a drain plug E2 in the portion thereof. The interior of tank it is erably provided with a liner l3 of suitable insu lating material. A suitable cover it preferably formed of cast iron is threadedly attached to tank I I as indicated at l5.

Bolted or otherwise suitably fastened to the cover H of oil fuse cutout i0 is a suitable ring 1'6 of insulating material which depends from. the cover so as to be almost wholly contained i l casing H. The insulating ring l8 supports flat stationary contacts l1. As best indicated in 2, these flat stationary contacts I! are self-align. ing by virtue or the pin and slot connections indicated at l8 and I9 respectively. Further more, each of these contacts is spring biased by means of a helical spring 20 tending to push fiat contacts ll toward the center of insulating l6. Two contacts H are provided which are mounted diametrically opposite one another with. respect to cylindrical tank II and each of these contacts is connected by suitable conductors 2i and 22 with an external electrical circuit through suitable entrance bushings 23, as shown in Fig. 1. Tank II is filled with a suitable dielectric, such as oil for example, to the level indicated in Fig. l.

The portion of the oil-filled cutout Ill described thus far may be substantially identical with the cutout disclosed in Patent 1,248,090 referred to above and forms no part of my present invention. Consequently, it has only been briefly de scribed since a detailed description thereof is available in the above mentioned United States Letters Patent.

The cover it of oil fuse cutout I0 is provided with a central opening 24 through which is in serted a fuse carrier generally indicated at 25. This fuse carrier comprises a metal cap 26 having ventilating or breathing openings 21 therein. A rectangular opening 26' is provided so that any handy lever may be inserted to assist in turning the fuse carrier. The top of this cap is provided with a hood 28. Cap 26 is provided with an annular flange 29 to suitably seat on an upturned flange 30 surrounding the opening 24 in cover M. A suitable gasket 3i may be in terposed between flanges 29 and 30 for sealing purposes. Cap 26 also includes a depending flange 32 extending into the opening 24 of cover it. A suitable plug such as 33, preferably formed of 9. treated wood, is provided with an upper portion of cylindrical form which" fits snugly into an opening or recess in depending flange 32 of cap and is pinned thereto by a. suitable pin or rivet 33'. This portion of wood plug 33 inserted in the lower portion of cap 26is provided with two flat sides such as 34 to provide breathing or vent ing passageways 35 from within the casing of cutout 16 to the exterior through the vent openings 21. As is disclosed in the above mentioned Patent 1,195,790 the cover 14 and the cap 26 are provided with suitable locking means so that flanges 29 and 30 may be maintained in sealing engagement with one another through gasket 31 when the fuse carrier 25 is in the position indicated in Fig. 1. This locking means is not shown in the drawing.

Fuse carrier 25 further includes supporting means for the movable contacts to be described hereinafter comprising a generally cylindrical member 36 of insulating material having an annular recess 36 provided in the upper portion thereof to accommodate wood plug 33. Suitably fastened. to the lower portion of movable contact supporting means are movable contacts i and Movable contact 31 has a downwardly extending portion 39 while contact 38 has an up-- wardly extending portion 46, both of which are suitably fastened to contact supporting member 36 by fuse link attachment screws 4 I. Flat headed screws 42 extend through

movable contacts

31 and 38 into member 36, thereby firmly supporting the

contacts

31 and 38 on member 36. These contacts are somewhat concave in form with respect to the portion thereof engaging member 36 and are adapted to make electrical contact with fiat contacts ll. Ihe circuit at contacts 3'! and I7 and contacts 38 and i1 is made and broken by rotating fuse carrier 25 in a manner clearly described in the above mentioned United States Letters Patent.

Surrounding the upper portion of movable contact support 36 is a guide supporting cylinder 44 formed of insulating material which in turn sup-- ports insulating guides 45 best shown in Figs. 3 and 4. Insulating guides 45 are attached to guide supporting member 44 by means of screws or other suitable supporting means 46 and 61. These screws are sufilciently long to also threadedly engage not only the openings 46 in cylinder 45 but also the openings 49 in the upper part of movable contact supporting member 36. Furthermore, the screws 61 are long enough to engage the openings 50 in wood plug 33 indicated in Fig. 4, thereby making the fuse carrier 25 in effect a unitary structure. The insulating guide members 45 which are preferably formed of insulating material are adapted to engage cooperating slots (not shown) in the cover member H adjacent opening 24 to insure that fuse carrier 25 is inserted only in a predetermined manner with the

contacts

31 and 38 thereof rotated to a position out of line with stationary contacts 11. After the fuse carrier 25 is fully inserted the guide members 45 are substantially free of the cooperating slots (not shown) in cover member l4 so that fuse carrier 25 may be rotated and

contacts

37 and 38 may then engage stationary fiat contacts ll. At the same time the locking means referred to above and disclosed in the above mentioned United States Letters Patent 1,195,790 comes into play to lock fuse carrier 25 in position so that flanges 29 and 30 are in sealing engagement with the gasket 3! therebetwe'en.

In order to provide a fuse arrangement embodying the oil blast principle in which two arcs are produced substantially instantaneously and series with each other upon the blowing of a single fusible element, I have provided within contact supporting member 36 a metallic pressure chamber or reservoir 52 which comprises a cylindrical member 53 and

end members

54 and 55 each having an opening such as 56 and 5 respectively, therein. The metallic chamber 52 comprising

members

53, 56 and 55 is supported within cylindrical member 36 by annular insulating supporting means 58 and 55 which are fastened by suitable insulating screws 66 to member 36 provided with cooperating openings 61. A fuse link is provided generally indicated at 62 comprising a fusible element 63 having suitable terminals 64 at either end thereof connected to

flexible cable loops

65 and 65. Flexible cable loops 65 and 65' are adapted to be slipped over fuse links supporting screws 6| to support the fuse link 62 in the position shown in Fig. 1. Loop 65 is made less flexible than loop 65 as one means for controlling the length of the arc and thereby to generate more gas and thus to provide greater pressure in the one portion than in the other so as to aid in directing the blast in the dc sired direction. By making cable 65' less flexible than cable 65 the lower arc is permitted to grow longer faster than the upper arc and hence produce an upwardly directed oil blast. If desired, a suitable strain wire 66 may be connected in parallel with fusibl element 63 between terminals 64.

Upon the occurrence of predetermined current conditions fusible element 63 will melt and an arc will occur between terminals 64. However, due to the prorimity of the walls of reservoir chamber 52 to arcs, one to member 56 and the other to member 55, will. occur substantially simultaneously. Since the opening in member 58 is larger and shorter than the opening in member 59, the lower arc will tend to produce greater pressure and thus an oil blast from the reservoir chamber 52, which blast is forced through the upper arc to extinguish the same. Also, the opening 56 in member 54 is smaller than the opening 5'! in member 55 so that the lower arc will be longer and tend to produce greater pressure. Suitable Openings 6! are provided in member 36 to permit free escape of the oil blast to the upper oil level, whereas the blasting of fluid from the lower end of the lower opening 51 is restricted by the greater head of oil as provided by the vertical arrangement at openings 56 and 51 and reservoir chamber 52 on the vertically inserted fuse carrier 25. Where necessary, a further restriction of the blast from the lower end of opening 51 can be provided by the addition of suitable baffles or the like. Similarly, member 36 is provided with an opening 66 through which the flexible cable 65 may extend to engage electrically the contact 38. In order that guide supporting cylinder 46 will not interfere with the operation of oil blast openings 61 or opening 63 it is provided with

recesses

66 and 10. It should be underst )od that my invention is not limited to the specific means or combination of means for directing the fluid blast and the direction of said blast as herein described, since other means for accomplishing this will suggest themselves to those skilled in the art.

From th above description it will be obvious that the length of the fusible element 63 and the length of the pressure chamber 52 may be so adjusted that when the fusible element ruptures the arc will tend to jump at once from upper fusible terminal 64 to the edge of pressure chamber 52 surrounding opening 56 and from the edge "by the lower arc will blast. the fluid in pressure chamber 52 through the upper arcto extinguish it and thereby interrupt the circuit through fuse '-I have found it desirable to construct the mewtallic chamber or oil reservoir comprising mem- ;

bers

53, 54 and 55 of steel since steel affords appreciableresistance to current-flow, thereby tending to limitthe current belowthe values which might otherwise beattained. This is desirableandhelpful in extinguishing the arc.

In viewyof the detailed description included above, the operation of the fuse cutout operating on the oil blast principle embodying my invention will be obvious and no further discussion will be included here. It will be observed that the fuse carrier 25 embodying my invention may replace the fuse carrier of prior art fuses of the .type similar to cutout l0.

The metallic chamber or oil reservoir comprising members 53, .54, and 55 may be constructed to have short gaps between the respective members so as to produce short arcs at an advantageous position within the oil reservoir to produce a blast of fluid through both of the other arcs. In Fig. 6 I have illustrated the metallic pressure chamber of Figs. 1 and 5 with the parts thereof separated by insulating washers H and 12 which may be constructed of fiber or the like.

-In this way the oil in the reservoir may be used to the greatest possible extent.

While I have shown and described a particular embodiment of my invention, it will be obvious -.to those skilled in the'art that various changes and modifications may be made without departing from my invention in its broader aspects and I therefore aim in the appended claims to cover all-such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electric circuit interrupting device of the fluid blast type, an arc chamber of conducting material containing an arc-extinguishing liquid, means defining a pair of openings one at each end of said are chamber, and a fuse link including a fusible element having a single rupturable section extending through said openings so that said fusible element is in said are cham- :ber immersed in said liquid, said fusible element being so arranged that upon rupture of said fusible element two arcs in series are produced substantially simultaneously between said. fuse link and said first mentionedmeanswith one of said arcs producing a fluid blast to extinguish said other arc.

2. In an electric circuit interrupting device of the fiuid blast type, a fuse carrier, an arc chamber of conducting material supported on said carrier, means defining a. pair of openings one at each end of said are chamber, a fuse link including a fusible element supported by said carrier and extending through said openings with said fusible element in said are chamber, said fusible element and said arc chamber being so arranged that upon rupture of said fusible element two arcs in series are produced substantially simulblast type comprising an arc chamber containing an arc-extinguishing liquid, and a fusible element having a single rupturable section immersed and arranged to rupture in said liquid in said chamber. said chamber and said fusible element being so arranged that upon rupture of said fusible ele- .ment two, arcs in series are producedsubstantially simultaneously, and means for at least partially confining the. escape of the fluid blast caused by one of said arcs to produce a fluid blast to extinguish said other arc.

- 4.- An electric circuit interrupter of the fluid blast type comprising an arc chamber containing an arc-extinguishing liquid, and a fusible element immersed and arranged to rupture in said liquid in said chamber, said chamber and saidfusible element being so arranged that upon rupture of said fusible element two arcs in series are produced substantially simultaneously, and means for increasing the arc gas pressure created by one of said arcs to provide a fluid blast to extinguish said other arc.

. with electrically conductive material, and a single circuit opening means immersed and arranged to draw an arc in said liquid in said chamber, said electrically conductive lining and said circuit opening means being so arranged that upon the drawing of the arc, two arcs in series are produced substantially simultaneously with. one of saidarcs producing a fluid blast from the reservoir portion of said chamber to extinguish said other arc.

6. An electric circuit interrupter of the fluid blast type comprising an arc chamber containing an arc extinguishing liquid, an electrically conducting member in said chamber, and a single circuit opening means immersed and arranged during a circuit opening operation to produce an arc in said liquid in said chamber, said electrically conducting member and said circuit opening meansbeing so arranged that upon I the production of said arc, two arcs in series are produced substantially simultaneously with one of said arcs producing a fluid blast to extinguish said other arc.

7. An electric circuit interrupter of the fluid blast type comprising an arc chamber containing an arc-extinguishing liquid, said are chamber comprising means defining two relatively small openings with an enlarged liquid containing reservoir therebetween, and a circuit opening means immersed and arranged to draw an arc in said liquid in said chamber, said chamber and said circuit opening means being so arranged that upon the drawing of the arc, two arcs in series are produced substantially simultaneously in said two small openings of said chamber with one of said arcs producing a fluid blast from said reservoir to extinguish said other arc.

8. An electric circuit interrupter of the fluid blast type comprising an arc chamber containing an arc extinguishing liquid, said are chamber comprising means defining two relatively amazes small openings with an enlarged liquid containing reservoir there between, said openings dii iering dimensionally from each other, and a cirrig means immersed and arranged to aw in said liquid in said chamber, said chamber and said circuit openng means being so arranged that upon the drawing of the arc, two arcs in series are produced substantially simultaneously in said two small openings of said chamber with one of said arcs producing a fluid blast from said reservoir to extinguish said other arc.

9. An electric circuit interrupter of the fluid blast type comprising an arc chamber containing an arc extinguishing liquid, said arc chamber comprising means defining two relatively small openings with an enlarged liquid containing reservoir therebetween, a circuit opening means immersed and arranged to draw an arc in said liquid said chamber, said chamber and said circuit opening means being so arranged that upon the drawing of the arc, two arcs in. series produced substantially simultaneously in said two small op nin s of said chamber, and means for produca dfierential in the relative pressures genmeans, a vertically removable carrier for said circuit opening means mounted in said cas nl. a cylindrical arc chamber supported in said carrier, an arc extinguishing liquid in said casing and in said chamber, and means defining a pair of vertically spaced openings one at each end of said chamber so the head of said liquid above the lower 01' said openings is greater than above the other of said openings, said circuit opening means being immersed and arranged to produce an arc in said liquid in said chamber, said chamber and said circuit opening means being so arranged in said carrier that upon the production of said are two arcs in series are produced substantially simultaneously in said'two openings with the arc in said lower opening producing a fluid blast through said upper opening to extinguish said other arc in said upper opening.

RALPH S. BENNETT.

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

UhI'lED STATES PATENTS Number Name Date 2,049,318 Prince July 28, 1938 Re. 20,450 Hill July 20, 193'! 2,185,039 smith Dec. 26, 1939 2,337,872 Craig Dec. 28, 1943