US3575682A

US3575682A - Expulsion fuse and condenser in a horizontally slidable drawer

Info

Publication number: US3575682A
Application number: US857676A
Authority: US
Inventors: Harold H Fahnoe
Original assignee: S&C Electric Co
Current assignee: S&C Electric Co
Priority date: 1969-09-15
Filing date: 1969-09-15
Publication date: 1971-04-20
Anticipated expiration: 1988-04-20
Also published as: GB1260648A

Abstract

A drawer mounted expulsion fuse has a sealed plug-in connection to the midsection of a stationary tubular condenser housing provided with a deflector for directing the exhaust products from the fuse into a cooling and condensing device at each end of the housing.

Description

United States Patent Harold ll. Fahnoe Evanston, Ill.

Sept. 15, 1969 Apr. 20, 1971 S 8: C Electric Company Chicago, Ill.

Inventor App]. No. Filed Patented Assignee EXPULSION FUSE AND CONDENSER IN A HORIZONTALLY SLIDABLE DRAWER 15 Claims, 3 Drawing Figs.

US. Cl. 337/282 Int. Cl H0lh 85/38 Field ofScarch ZOO/149.1;

[56] References Cited UNITED STATES PATENTS 3,258,568 6/1966 Patterson et al. 3 37/249( X) 2,386,886 10/1945 Earle et a1 337/281 2,331,778 10/1943 Hill 337/282(X) 2,167,499 7/1939 Dickenson 337/282( X) 2,084,979 6/1937 Slepian ..200/l49. 1(UX) Prirhary ExaminerBemard A. Gilheany Assistant Examiner-Dewitt M. Morgan Attorney-Robert R. Lockwood ABSTRACT: A drawer mounted expulsion fuse has a sealed plug-in connection to the midsection of a stationary tubular condenser housing provided with a deflector for directing the exhaust products from the fuse into a cooling and condensing device at each end of the housing.

SHEET 3 OF 3 PATENTED APR20 I971 EXPULSION FUSE AND CONDENSER IN A IIORIZONTALLY SLIDABLE DRAWER This invention is an improvement over the constructions disclosed in Harner et al. US. Pat. No. 3,339,l 18, issued Aug. 29, 1967, and Fahnoe US. Pat. No. 3,391,368, issued July 2, 1968.

When an expulsion fuse is mounted in a drawer, such as the drawer shown in the above Harrier et al. patent, it is desirable to support the fuse from one end in cantilever fashion with the free expulsion end arranged to discharge into an exhaust control device. Since the fuse is supported only at one end when it is withdrawn, it is undesirable to mount the exhaust control device on the exhaust end of the fuse because of the weight of the exhaust control device. With the drawer mounted expulsion fuse, the space endwise of its discharge end is limited. It is not feasible to employ the condenser or exhaust control device of the Fahnoe patent for this application.

Among the objects of this invention are: To provide for supporting an expulsion fuse at one end in a horizontally movable drawer with the other exhaust end telescoped with a stationary contact sleeve which forms a part of an exhaust control device; to provide a seal between the exhaust terminal of the expulsion fuse and the contact sleeve to prevent flow therebetween of products incident to operation of the expulsion fuse; to direct the flow of the expulsion products transversely of the expulsion fuse with part flowing in one direction and another part flowing in the opposite direction; to cool and condense each part of the expulsion products at the respective end of an elongated housing to the midsection of which the contact sleeve is connected; and to support the exhaust control device endwise of the expulsion fuse.

According to this invention an expulsion fuse is mounted at one end in a horizontally movable drawer forplug-in connection at its exhaust end with a stationary contact sleeve that is carried by a stationary exhaust control device. Rings in the grooved surface of the exhaust terminal of the fuse formed of a material having a relatively low coefficient of friction provide a seal to prevent flow of exhaust products between the contact sleeve and the exhaust terminal. The exhaust control device ,comprises an elongated tubular metallic housing having exhaust product cooling and condensing means at each end with a contact sleeve midway the ends and the fuse arranged to discharge directly against a conical exhaust product deflector which directs the flow of the exhaust product in opposite directions into the respective cooling-and condensing means. A cradle carried by a stationary insulator positioned endwise of the expulsion fuse is secured to cars projecting from the housing. The exhaust product deflector, by directing the flow of the exhaust products in opposite directions, reduces the reaction against the insulator and neutralizes the reactions endwise of the housing with the result that a minimum of exhaust products are discharged from the ends of the housing and a minimum of space is required between adjacent phases and a minimum size of enclosure for single phase or polyphase installations can be used.

In the drawings:

FIG. I is a perspective view of a fuse drawer in closed position and carrying fuses of the expulsion-type for plug-in connection with T-shaped exhaust control devices.

FIG. 2 is a top plan view, certain parts being. shown in section, of one of the fuses and exhaust control devices in assembled relation.

FIG. 3, sheet I, is a vertical sectional view taken generally along line 3-3 of FIG. 2.

FIG. 4 is a horizontal sectional view of the expulsion fuse.

FIG. 5 is a view, in end elevation, of the cylindrical exhaust terminal of the expulsion fuse.

FIG. 6 is a horizontal sectional view taken generally along line 6-6 of FIG. 3 and shows certain details of construction of the exhaust control device.

FIG. 7 is a view, in end elevation, of one of the covers or end plates for the exhaust control device.

In FIG. I the reference character 10 designates, generally, a fuse drawer for use particularly in the switchgear described in the above application. The fuse drawer I0 includes a metallic fuse panel 11 from which upper and

lower channel members

12 and 13 extend rearwardly to form a frame structure. Vertical support plates 14 interconnect the channel members 12 and I3. Insulating barrier plates 15 are provided in parallel spaced relation with respect to expulsion fuses which are indicated, generally, at 16. For a three-phase system, three expulsion fuses 16 are employed. Also extending rearwardly from the rear side of panel 11 are metallic brackets 17 from which insulators 18 project inwardly of the fuse drawer 10. Each of the insulators 18 has a metallic end cap 19.

Fuse terminal brackets 22 are mounted at the distal ends of the insulators 18 on the metallic end caps 19. Contact arms 23 extend laterally and inwardly from the fuse terminal brackets 22 to provide connections to switch blades which are arranged to connect the fuses 16 for energization into a loop circuit. Each of the expulsion fuses 16 includes a fuse tube 24 of insulating material having a cylindrical exhaust terminal 25 at its inner end for plug-in contact engagement with T-shaped exhaust control devices indicated, generally, at 26. The control devices 26 are mounted on metallic end caps 27 of stationary insulators 28 which are mounted on a rear panel of the switchgear (not shown).

In FIG. 4 the details of construction of one of the expulsion fuses 16 .are shown. Within the fuse tube 24 there is an expulsion fuse assembly that is indicated, generally, at 31. It includesa terminal stud 32 which extends through the end of the exhaust terminal 25 and is secured in place by nuts 33. To the inner end of the terminal stud 32 a strain wire 34 and a fusible element 35 are connected. They are located in a metallic exhaust chamber 36. The other ends of the strain wire 34 and fusible element 35 are connected to one end of an arcing rod 37 which is movably mounted in a bore 38 in a lining 39 of arc extinguishing material, such as boric acid. Adjacent the exhaust chamber 36, the bore 38 opens into an enlarged bore section 40. At the opposite end of the arcing rod 37 there is a contact button 43 that is arranged to be engaged by contact fingers 44 of an arcing rod sleeve 45. A garter spring 46 acts to bias the distal ends of the contact fingers 44 into good contact engagement with the cylindrical surface of the contact button 43. The arcing rod sleeve 45 extends from an arcing rod sleeve stop 47. A metallic collar 48 surrounds the contact fingers 44 to prevent spreading thereof when relatively heavy short circuit current flows therethrough. The metallic arcing rod sleeve stop 47 is connected to one end of a conducting tube 49 which extends along the inside of the fuse tube 24 to the left end where it has a press fit with a knurled head 50 of an end plug 51. A threaded stud 52 extends laterally from the end plug 51.

As shown in FIG. 2 the threaded stud 52 is arranged to be screwed into the metallic end cap 19. When the fuse drawer I0 is withdrawn, the fuse I6 is supported in a cantilever fashion by the threaded stud 52. The entire weight of the fuse 16, including the weight of the cylindrical exhaust terminal 25, is then supported only by the stud 52. The overall length of the fuse to may be of the order of 18 inches. Thus it is desirable to have a minimum of weight at its distal end to be supported by the threaded stud 52, when the fuse drawer 10 is opened. In addition to supporting the fuse 16 the threaded stud 52 acts as a terminal to provide a connection to the fuse terminal bracket 22 from which the contact arms 23 extend. An end plug retainer ferrule 53 overlies the end of the fuse tube 24 and the end plug 51 to assist in holding the latter in position and to provide contact engagement with the fuse terminal bracket 22.

For moving the arcing rod 37 through the bore 38 on blowing of the fusible element 35 and the strain wire 34, a coil compression spring 54 is provided. At its inner end it reacts against the arcing rod sleeve stop 47. At its outer end it reacts against a flange 55 on a spring insulator 56 which bears against a spring cap 57 to which one end of an arcing rod extension 58 is secured. The other end of the arcing rod extension 58 forms an integral part of the arcing rod 37. A filling of an epoxy resin 59 between the inner surface. of the fuse tube 24 and the outer surface of the lining 39 of arc extinguishing material and the outer surface of the conducting tube 49 provide an integral construction.

When the fusible element 35 and strain wire 34 blow as a result of an overload or short circuit, an arc is formed between the remaining ends of the strain wire 34 and the fuse element 35 or between the terminal stud 32 and the retreating end of the arcing rod 37. Since the arcing rod 37 no longer is restrained, it moves through the enlarged bore section 30 into the bore 38 under the influence of the coil compression spring 54. The end plug 51 effectively closes off the adjacent end of the conducting tube 49. The products incident to the are thus drawn and incident to evolution of gas from the arc extinguishing material 39 are required to flow outwardly through the metallic exhaust chamber 36 and to flow through arcuate exhaust openings 60, FIG. 5, in the outer end of the cylindrical exhaust terminal 25. Here it will be observedthat the exhaust openings 60 are provided on opposite sides of a bridge section 61 through which the terminal stud 32 extends. The products incident to the drawing of the arc are discharged into the exhaust control device 26 in which some back pressure may be developed. It is desired that none of the are products flows reversely over the cylindrical exhaust terminal 25 where it is plugged into the exhaust control device 26.

As shown in FIGS. 2 and 4 the exhaust terminal 25 has a reduced diameter cylindrical end section 63 that is arranged to telescope within a cylindrical interior surface 64 of an adapter or contact sleeve 65 which opens into the control device 26. The adapter or contact sleeve 65 extends through a I suitable opening in a wall 66 of an elongated tubular metallic housing 67 which forms a part of the control device 26. The adapter or contact sleeve 65 and the elongated metallic housing 67 provide a generally T-shaped configuration. Annular grooves 68 are formed in the reduced diameter end section 63 of the exhaust terminal 25 for receiving sealing rings 69 which are formed of a material having a relatively low coefficient of friction. For example they may be formed of tetraflurorethylene of which Teflon is an example. The sealing rings 69 are large enough in cross section to snugly engage the cylindrical interior surface 64 of the adapter or contact sleeve 65 and thus they prevent flow therepast of the are products which are discharged through the exhaust openings 60 into the tubular metallic housing 67.

In order to provide a good electrical connection between the exhaust terminal 25 and the adapter or contact sleeve 65 a contact sleeve extension 70 of a good conducting material, such as copper alloy, overlies the adapter or contact sleeve 65 and has contact fingers 71 which are urged by garter springs 72 into good contact engagement with a cylindrical contact section 73 of the exhaust terminal 25. A clamp nut 74, threaded on the adapter or contact sleeve 65, holds the contact sleeve extension 70 in good contact engagement therewith.

FIGS. 3 and 6 show the details of construction of the exhaust control device 26. It will be noted that an exhaust product deflector 75 is located in the wall 66 of the tubular metallic housing 67 .in alignment with the opening through the adapter or contact sleeve 65 so that the are products flowing through the exhaust openings 60 in the exhaust terminal 25- directly impinge thereon. The exhaust product deflector 75 may be formed of a copper alloy and it has a cylindrical base portion 76 which extends through a suitable opening in the wall 66 of the metallic housing 67 and is suitably secured thereto. Extending inwardly from the base portion 76 is an integral conical section 77 which has an apex angle of 90". As a result the high velocity flow of arc products from the fuse I6 is redirected principally toward the opposite ends of the housing 67. Since the reactions due to the high velocity flow of arc products are equal and opposite, they tend to neutralize and to confine the resultant forces to tension of the walls 66 of the housing 67 which are of ample strength to resist such forces. Exhaust product cooling and condensingmeans, indicated generally at 78, are provided at the ends of the housing 67. They include helical coils 79 of heavy wire mesh which are wound around metallic studs 80 and between washers 81 at the inner ends of the studs 80 and covers or metallic end plates 82 at the outer ends. The covers or end plates 82 are located in grooves 83 near the ends of the housing 67 and the edges 84 thereof are turned over to hold the covers or end plates 82 in place. In FIG. 7 one of the covers or end plates 82 is shown. It is provided with a number of exhaust openings 85 which relieve the pressure that is generated within the housing 67 on blowing of the fuse 16.

In order to provide a rugged support for the exhaust control device 26 on the insulator 28, support means, indicated generally at 87 is employed. It comprises a channel-shaped cradle 88 as shown in FIG. 3. The cradle 88 is located in overlying relation and symmetrically with respect to the exhaust product deflector 75. ltsends 89 overlie cars 90 that are welded or otherwise secured to the outer surface of the wall 66 of the housing 67. Bolts 91 interconnect the ends 89 of the channel-shaped cradle 88 and the ears 90. Flat. head screws 92 extend through the bottom of the channel-shaped cradle 88 into the metallic end cap 27 on the insulator 28 to holdthe assembly including the control device 26 securely in place. Also this provides an electrical connection to the inner or distal end of the fuse 16 which is completed, for example, by a conductor rod extending through the insulator 28 and projecting rearwardly thereof for connection to a suitable load conductor.

According to the above Fahnoe patent an exhaust control device is mounted on the fuse housing and constitutes an endwise extension thereof. This arrangement provides a relatively heavy assembly and difficulty may be encountered in handling it. As disclosed herein before, the exhaust control device 26 is stationarily mounted on the insulator 28 and the fuse 16 is arranged to have plug-in contact engagement therewithwhen the exhaust terminal 25 is inserted into the adapter or contact sleeve 65 on movement of the drawer 10 to the closed position. This plug-in arrangement makes it possible to support the expulsion fuse 16 in cantilever fashion on the insulator 18 since only the weight of the fuse 16 need be taken into consideration.

When the fuse 16 operates or blows, the products incident to this operation flow through the dual exhaust openings 60 in the exhaust terminal 25 and are directed in opposite directions in the metallic housing 67 where they 'impinge upon the exhaust product deflector 75. Approximately one-half of the arc products are directed toward each of the exhaust product cooling and condensing means 78 thereby reducing correspondingly the volume of gas for each of them over that involved in the exhaust control device of the Fahnoe patent. Since the volume of are products applied to each of the cooling and condensing means 78 is reduced the exhaust control device 26 has a relatively long life and it can be used without replacement for many fuse operations. Because of the reduced mechanical reaction due to the opposing flows of the arc products in the control device 26, the mechanical reaction of the fuse 16 on the insulator 18, which supports it, is correspondingly reduced.

Iclaim:

I. An exhaust control device for an expulsion fuse comprising:

exhaust products from said expulsion fuse toward said ends of said housing.

2. The exhaust control device accordingto claim 1 wherei said exhaust product deflector is a conical metallic member secured to a wall of said housing.

3. The exhaust control device according to claim 2 wherein, the angle at the apex of said conical member is about 90 and said apex is symmetrical with respect to the path of said exhaust products to neutralize the reaction thereof endwise of said elongated housing and on a support for said elongated housing.

4. The exhaust control device according to claim 1 wherein means are provided on said elongated housing in alignment with said exhaust product deflector for supporting said exhaust control device on insulating support means.

5. The exhaust control device according to claim 4 wherein said support means includes cradle meanssecured to said elongated housing.

6. A circuit interrupter comprising:

an expulsion fuse having an exhaust terminal at one end,

and

an exhaust control device at said one end including:

a housing extending transversely of said exhaust terminal having an opening in awall intermediate its ends,

means interconnecting said exhaust terminal and said opening opposite a wall of said housing against which exhaust products of said expulsion fuse can be discharged, and

exhaust product cooling and condensing means at each end of said housing, and

an exhaust product deflector in said housing in alignment with said exhaust terminal for deflecting the exhaust products from said expulsion fuse toward said ends of said housing.

7. The circuit interrupter according to claim 6 wherein:

said exhaust tenninal has a cylindrical external surface, and

said means interconnecting said exhaust terminal and said housing comprises a contact sleeve having a cylindrical interior surface for telescopically receiving said exhaust terminal.

8. The circuit interrupter according to claim 8 wherein:

a mounting terminal is secured to the other end of said expulsion fuse to support it in cantilever fashion on insulating support means, and

means are provided on said housing for mounting said exhaust control device on insulating support means.

9. In combination:

an expulsion fuse arranged to discharge at one end,

means mounting the other end of said expulsion fuse on a horizontally movable drawer,

a contact sleeve mounted on a stationary insulator for connection to and receiving said discharge end of said expulsion fuse when said drawer is closed,

an elongated housing extending transversely of said contact sleeve and having an opening in a wall intermediate its ends such that said expulsion fuse on blowing discharges into said housing through said opening against an opposite wall,

exhaust product cooling and condensing means at each end of said housing, and

an exhaust product deflector in said housing in alignment with said one end of said expulsion fuse.

10. The combination according to claim 9 wherein sealing means between said discharge end of said expulsion fuse and said contact sleeve prevent flow therebetween of products incident to operation of said expulsion fuse. i

11. The combination according to claim 9 wherein: said contact sleeve is carried by said elongated housing is supported by said stationary insulator, and

12. The combination according to claim 11 wherein: means are provided on said elongated housing in alignment with said exhaust product deflector supporting said housing relative to saidstationary insulator.

13. The combination according to claim 16 whereln said support means includes cradle means secured to said 0 elongated housing.

14. A circuit interrupter comprising: an expulsion fuse having an exhaust terminal at one end,

and an exhaust control device at said one end including:

a housing extending transversely of said exhaust tenninal, means interconnecting said exhaust terminal and said housing intermediate the ends of said housing, exhaust product cooling and condensing means at each end of said housing, said exhaust terminal having a cylindrical externally grooved surface, said means interconnecting said exhaust terminal and said housing comprising a contact sleeve having a cylindrical interior surface for telescopically receiving said exhaust terminal, and sealing ring means in said grooved exhaust terminal to prevent flow of products incident to operation of said expulsion fuse between said exhaust terminal and said contact sleeve. 15. In combination: an expulsion fuse arranged to discharge at one end, means mounting the other end of said expulsion fuse on a horizontally movable drawer,

I a contact sleeve mounted on a stationary insulator for connection to and receiving said discharge end of said expulsion fuse when said drawer is closed,

an elongated housing extending transversely of said contact sleeve such that said expulsion fuse on blowing discharges into said housing intermediate its ends,

exhaust product cooling and condensing means at each end of said housing,

an exhaust terminal at said one end of said expulsion fuse,

and

sealing means comprising one or more sealing rings of a material having a relatively low coefficient of friction in the grooved exterior of said exhaust terminal.

gg g UNITED STATES PATENI OFFICE CERTIFICATE OF CORRECTION Patent NO. 3,575,682 Dated April 20, 1971 Inventordi) Harold H. Fahnoe It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 12 after "housing" insert and said elongated housing Column 6, line 13 for and" substitute period( Column 6, line 17 for "16" read l2 Signed and sealed this 15th day of February 1972.

(SEAL) Attest: 4

EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents

Claims

1. An exhaust control device for an expulsion fuse comprising: an elongated housing having an opening in a wall intermediate its ends, means for interconnecting the exhaust end of said expulsion fuse and said opening opposite a wall of said housing against which products of said expulsion fuse can be discharged, exhaust product cooling and condensing means at each end of said housing, and an exhaust product deflector in said housing in alignment with said interconnecting means for deflecting the exhaust products from said expulsion fuse toward said ends of said housing.

2. The exhaust control device according to claim 1 wherein said exhaust product deflector is a conical metallic member secured to a wall of said housing.

3. The exhaust control device according to claim 2 wherein the angle at the apex of said conical member is about 90* and said apex is symmetrical with respect to the path of said exhaust products to neutralize the reaction thereof endwise of said elongated housing and on a support for said elongated housing.

5. The exhaust control device according to claim 4 wherein said support means includes cradle means secured to said elongated housing.

6. A circuit interrupter comprising: an expulsion fuse having an exhaust terminal at one end, and an exhaust control device at said one end including: a housing extending transversely of said exhaust terminal having an opening in a wall intermediate its ends, means interconnecting said exhaust terminal and said opening opposite a wall of said housing against which exhaust products of said expulsion fuse can be discharged, and exhaust product cooling and condensing means at each end of said housing, and an exhaust product deflector in said housing in alignment with said exhaust terminal for deflecting the exhaust products from said expulsion fuse toward said ends of said housing.

7. The circuit interrupter according to claim 6 wherein: said exhaust terminal has a cylindrical external surface, and said means interconnecting said exhaust terminal and said housing comprises a contact sleeve having a cylindrical interior surface for telescopically receiving said exhaust terminal.

8. The circuit interrupter according to claim 8 wherein: a mounting terminal is secured to the other end of said expulsion fuse to support it in cantilever fashion on insulating support means, and means are provided on said housing for mounting said exhaust control device on insulating support means.

9. In combination: an expulsion fuse arranged to discharge at one end, means mounting the other end of said expulsion fuse on a horizontally movable drawer, a contact Sleeve mounted on a stationary insulator for connection to and receiving said discharge end of said expulsion fuse when said drawer is closed, an elongated housing extending transversely of said contact sleeve and having an opening in a wall intermediate its ends such that said expulsion fuse on blowing discharges into said housing through said opening against an opposite wall, exhaust product cooling and condensing means at each end of said housing, and an exhaust product deflector in said housing in alignment with said one end of said expulsion fuse.

10. The combination according to claim 9 wherein sealing means between said discharge end of said expulsion fuse and said contact sleeve prevent flow therebetween of products incident to operation of said expulsion fuse.

12. The combination according to claim 11 wherein: means are provided on said elongated housing in alignment with said exhaust product deflector supporting said housing relative to said stationary insulator.

13. The combination according to claim 16 wherein said support means includes cradle means secured to said elongated housing.

14. A circuit interrupter comprising: an expulsion fuse having an exhaust terminal at one end, and an exhaust control device at said one end including: a housing extending transversely of said exhaust terminal, means interconnecting said exhaust terminal and said housing intermediate the ends of said housing, exhaust product cooling and condensing means at each end of said housing, said exhaust terminal having a cylindrical externally grooved surface, said means interconnecting said exhaust terminal and said housing comprising a contact sleeve having a cylindrical interior surface for telescopically receiving said exhaust terminal, and sealing ring means in said grooved exhaust terminal to prevent flow of products incident to operation of said expulsion fuse between said exhaust terminal and said contact sleeve.

15. In combination: an expulsion fuse arranged to discharge at one end, means mounting the other end of said expulsion fuse on a horizontally movable drawer, a contact sleeve mounted on a stationary insulator for connection to and receiving said discharge end of said expulsion fuse when said drawer is closed, an elongated housing extending transversely of said contact sleeve such that said expulsion fuse on blowing discharges into said housing intermediate its ends, exhaust product cooling and condensing means at each end of said housing, an exhaust terminal at said one end of said expulsion fuse, and sealing means comprising one or more sealing rings of a material having a relatively low coefficient of friction in the grooved exterior of said exhaust terminal.