US3711809A

US3711809A - Open type fuse

Info

Publication number: US3711809A
Application number: US00209876A
Authority: US
Inventors: C Baker; H Scherer
Original assignee: S&C Electric Co
Current assignee: S&C Electric Co
Priority date: 1971-12-20
Filing date: 1971-12-20
Publication date: 1973-01-16
Anticipated expiration: 1990-01-16

Abstract

The biased apart contact arms of an open type fuse mounting are interconnected by a liquid fuse having clips detachably secured to the ferrules at the ends of the liquid fuse tube and detachably secured to contacts at the distal ends of the contact arms, the fuse assembly remaining in place under tension after blowing of the fuse.

Description

United States Patent [191 Baker et al.

[ 1 Jan. 16, 1973 OPEN TYPE FUSE Inventors: Charles H. Baker, Evanston; Henry W. Scherer, Niles, both of 111.

Assignee: S & C Electric Company, Chicago,

Filed: Dec. 20, 1971 Appl. No.: 209,876

US. Cl ..337/l90 Int. Cl. ..H0lh 85/36 Field of Search.....337/190, 168, 178; 24/261 A,

24/261 B, 261 C, 3 D; 339/256 S, 256 C References Cited UNITED STATES PATENTS 1,716,894 6/1929 Lindgren ..24/261 B 998,551 7/1911 Robertson.... ..339/256 S 3,058,083 10/1962 Schneider ..339/256 S 2,324,044 7/1943 Triplett et a1 ..337/190 Primary Examiner-Harold Broome AttorneyRobert R. Lockwood [57] ABSTRACT The biased apart contact arms of an open type fuse mounting are interconnected by a liquid fuse having clips detachably secured to the ferrules at the ends of the liquid fuse tube and detachably secured to contacts at the distal ends of the contact arms, the fuse assembly remaining in place under tension after blowing of the fuse.

6 Claims, 7 Drawing Figures PATENTEUJAN 16 ms SHEET 1 [IF 2 OPEN TYPE FUSE This invention relates, generally, to circuit interrupters of the fuse type and it has particular relation to open type fuse cutouts such as disclosed in Triplett et al U.S. Pat. No. 2,324,044 issued July 13, 1943.

Open type fuse cutouts have come into wide spread use by electric power distribution systems. They comprise an insulator arranged to be mounted overhead in an upright position on a suitable support and provided with laterally extending contact arms at the ends in vertical alignment. Usually the upper arm is stationarily mounted and the lower arm is biased for movement away from the upper arm to hold in tension a fuse link interconnecting contacts at the distal ends of the arms. On the occurrence of a sufficient overload, this fuse link blows and its terminals are separated by the biasing action of the lower arm. The blowing of the fuse link often is accompanied by spewing of molten metallic particles in the space below the fuse cutout. In the event that these molten particles fall on flammable material, such as dry grass, brush and the like, there is the likelihood that a tire may be started which is highly objectionable.

Accordingly, among the objects of this invention are: To provide an open type fuse cutout construction which, on blowing, does not distribute molten metallic particles over the space therebelow; to arrange for employing as the fuse link a liquid type fuse; to provide for making detachable connections to the ferrules at the ends of the tubular housing of a liquid fuse; for this purpose to provide spring wire clips for surrounding and reacting endwise against the ferrules with flexible leads extending therefrom having abutments for overlying contacts at the distal ends of biased apart contact arms; and to construct each fuse clip with an integral extension, instead of the flexible lead, which includes an eye member or ring as a further integral extension.

In the drawings:

FIG. 1 is a view, in side elevation, of an open type fuse cutout embodying this invention.

FIG. 2 is a view, similar to FIG. 1 but showing how the fuse assembly remains in place after the fusible element has blown.

FIG. 3 is a view, in side elevation, of one of the clip means detachably connected to the ferrule of a liquid fuse forming a part of the fuse assembly.

FIG. 4 is a sectional view taken generally along line 44 of FIG. 3.

FIG. 5 is a view, partly in section and partly in elevation showing a typical liquid fuse construction.

FIG. 6 is a view in side elevation, of an alternate form of clip means.

FIG. 7 is an elevational view of FIG. 6 taken along line 77.

Referring now to FIG. 1 of the drawings it will be observed that reference character 10 designates, generally, an open type fuse cutout in which this invention is embodied. The fuse cutout 10 includes an insula tor 11 that is provided with a centrally located laterally extending mounting bracket 12 for positioning on a suitable support, such as a crossarm or like support. At

its ends the insulator 11 is provided with upper and lower contact supports 13 and 14 carrying, respectively, upper and

lower line terminals

15 and 16. Also mounted on the contact supports 13 and 14 are upper and

lower contact arms

17 and 18 which have contacts l9 and 20 at their distal ends. The

contact arms

17 and 18 are relatively biased apart through the provision of a coil spring section 21 that forms a part of the lower contact arm 18. The

contacts

19 and 20 preferably are provided with contact receiving grooves in which a fuse assembly, indicated generally at 25, can be detachably mounted.

It will be understood that the open type fuse cutout 10 comprising the insulator 11 and contact

arms

17 and 18 is typical of a mounting for the fuse assembly 25 and that other forms of this cutout mounting arrangement can be employed. The particular mounting disclosed is for illustrative purposes.

As pointed out hereinbefore, when the

contacts

19 and 20 are interconnected by a conventional fuse link, there is the likelihood, when the fuse element of the fuse link blows in response to an overload, that molten metallic particles will be distributed in the space below the fuse cutout 10. Under certain conditions these molten particles may fall on relatively flammable material,

such as dry grass, brush, etc., with the result that a fire may be started. When the fuse cutout 10 is located in a remote area, such an accidental fire may be undiscovered and cause considerable damage before it can be extinguished.

In accordance with this invention, instead of the conventional fuse link there is provided the fuse assembly 25 which includes a liquid type fuse that is indicated, generally, at 26. The liquid fuse can be constructed as disclosed in Conrad U.S. Pat. No. 2,134,470, issued Oct. 25, 1938. A particular construction is illustrated in FIG. 5 where it will be observed that the liquid fuse 26 includes a fuse tube 27 that provides a fuse housing and may be formed of transparent glass. Within the fuse tube 27 there is a filling of arc extinguishingliquid 28. The fuse tube 27 is provided with upper and lower metallic"

ferrules

29 and 30 of cylindrical configuration and suitably sealed to the ends of the fuse tube 27. The

inner ends

31 and 32 of the

ferrules

29 and 30 provide shoulders against which portions of fuse clips react in a manner to be described. Within the fuse tube 27 there is provided a fusible element 33 which is connected at its upper end to the upper ferrule 29. At its lower end the fusible element 33 is connected to a terminal 34 which, in turn, is connected by a flexible conductor 35 to the lower ferrule 30. A coil tension spring 36 reacts between the terminal 34 and the lower ferrule 30 to withdraw the terminal 34 into the liquid 28 when the fusible element 33 blows. This is accompanied by downward movement of a liquid director 37 which causes the liquid 28 to flow into the arc space for extinguishing the are. If sufficient pressure is generated within the fuse tube 27 on blowing of the fusible element 33, a vent cap 38 may be blown off to permit the are products to flow upwardly as illustrated in FIG. 2 of the drawings. However, since the are products are discharged upwardly and are enveloped in the arc extinguishing liquid 28 and gas evolved therefrom there are no molten metallic particles which are distributed in the vicinity likely inadvertently to start a fire in the manner above described.

It will be understood that the liquid fuse 26 is of conventional construction. In accordance with this invention upper and lower clip means, indicated generally at 40 and 41, of identical construction are employed for 7 generally at 42, having a diameter of 0.128" and formed preferably of phosphor bronze wire. The spring wire 42 is formed into a generally circular intermediate portion 43 having an unstressed diameter slightly less than the diameter of the

ferrules

29 and 30 so that it can grip them when applied thereto. One end section 44 extends at right angles to the intermediate portion 43 and has an arcuate end portion 45 the radius of which is somewhat less than the radius of the intermediate portion 43 so that it can overlie the respective

inner end

31 and 32 of the

respective ferrule

29 and 30 to the end that an endwise tension can be applied to the respective clip means 40 and 41. The arcuate end portion 45 has an out turned distal end 46 to facilitate application and removal of the clip means 40 and 41 to and from the respective ferrule. Each of the intermediate portions 43 has an other end section 49 extending at right angles thereto and into a metallic sleeve connector 50. Also extending into the metallic sleeve connector 50 is one end of a flexible lead 51. The connector 50 is deformed at 52 to hold the other end section 49 and the one end of the flexible lead 51 securely in place and in good electrical interconnection since the entire current flow must take place between the respective spring wire 42 and the flexible lead 51. At the outer end of the flexible lead 51 there is a metallic sleeve connector 53 for receiving the lead 51 as well as ends 54 of a key hole eye member 55 of wire. The metallic sleeve connector 53 is deformed unto the flexible lead 51 and ends 54 to provide a unitary construction. Formed integrally with the metallic sleeve connector 53 is a flange 56 which provides shoulder means for overlying the

contacts

19 and 20 at the distal ends of the

contact arms

17 and 18. It will be understood that the key hole eye members 55 are provided for receiving a prong of a switch stick that is used for applying and removing the fuse assembly to and from the

contacts

19 and 20 at the ends of the

contact arms

17 and 18.

In operation the fuse assembly 25, comprising the liquid fuse 26 and upper and lower clip means 40 and 41, is positioned on the

contact arms

17 and 18 as illustrated in FIG. 1 of the drawings. Prior to application of the fuse assembly 25 to the

contact arms

17 and 18, the clip means 40 and 41 are applied to the ferrules 29 and by forcing them into the respective intermediate portions 43 until the arcuate ends portions 45 are positioned behind the inner ends 31 and 32 of the

ferrules

29 and 30. This is accompanied by a cleaning action along the surfaces of the

ferrules

29 and 30 and the juxtaposed surfaces of the intermediate portions 43, end sections 44 and arcuate end portions 45. This arrangement is such that a pull of 30 pounds tension force applied to the clip means and 41 can be readily withstood.

FIG. 2 shows that the fuse assembly 25, except for the fusible element 33, remains in place after the fusible element 33 blows. The reason for this is that there is a direct mechanical connection between the clip means 40 and 41 through the

ferrules

29 and 30 and the fuse tube 27 which is independent of the presence or absence of the fusible element 33. While the vent cap 38 may be blown off and some of the liquidarc extinguishing material 28 discharged, experience indicates that there is no distribution of molten metallic parts sufficient to support combustion in the space below the fuse cutout 10.

FIGS. 6 and 7 show, generally at 60, an alternate form of clip means for detachable connection to the

ferrules

29 and 30 of the liquid fuse 26. The clip means 60 is formed of one piece spring wire to provide a fer- 61 and terminates in an arcuate end portion 63 that overlies the

shoulder

31 or 32 on the ferrules ,29 and 30, as the case may be, to hold the respective clip means 60 in place and against endwise detachment until it is moved out of this overlying engagement. An other end section 64 extends at right angles from the other end of the ferrule clamping section 61 and has a flattened portion 65 for engaging the

respective contact

19 or 20 of the spring biased apart contact arms 17 and The spring wire clip means 60 terminates in an eye member or ring 66 to receive the prong of a switch stick for manipulating the fuse assembly 25 in which is incorporated two of the spring wire clip means 60. The eye member or ring 66 is formed with a space 67 to receive a washer 68 which is slid around to the position shown in FIGS. 6 and 7 where one side bears against one end of the flattened portion 65. It is secured in place by welding, brazing or soldering as indicated at 69. The washer 56 forms a shoulder for overlying the

respective contact

19 or 20.

The application of the clip means 60 to the liquid fuse 26 is the same as described for the clip means 40 and 41 to complete the fuse assembly25 which then can be applied to and removed from the

contacts

19 and 20 of the

contacts arms

17 and 18 by manipulation of a switch stick. As before, the fuse assembly 25 remains in place, as shown in FIG. 2, after blowing of the liquid fuse 25.

We claim:

1. A fuse device comprising, an insulator; a pair of contact arms mounted at one end on said insulator in spaced relation, each arm having a contact at its distal end, and said arms being biased for movement part, and a fuse assembly interconnecting said contact arms including an insulating housing having ferrules at its ends interconnected by fusible means, and clip means detachably secured to each ferrule, each clip means including a conductor extending endwise from said housing and detachably connected to the respective contact of said contact arms and holding them under tension, said fuse assembly being characterized by remaining in place under tension after blowing of said fusible means.

2. The fuse device according to claim 1 wherein said clip means includes a spring wire having an intermediate portion around the respective ferrule and one end portion overlying an inner end portion of the respective ferrule.

3. The fuse device according to claim 2 wherein said conductor comprises a flexible lead secured at one end to the other end portion of said spring wire, and shoulder means is secured to the other end of said flexible lead for overlying the respective contact.

4. The fuse device according to claim 1 wherein said fuse assembly includes a liquid type fuse.

5. The fuse device according to claim 1 wherein said clip means comprises a single piece of spring wire l0 formed to provide said conductor integral with said clip

Claims

5. The fuse device according to claim 1 wherein said clip means comprises a single piece of spring wire formed to provide said conductor integral with said clip means and an eye member for receiving a prong of a switch stick.

6. The fuse device according to claim 5 wherein said conductor has a flattened portion for engaging the respective contact, and a washer is secured to said conductor between said flattened portion and said eye member for bearing against the respective contact.