US2793267A - Contact construction - Google Patents

Description

May 21, 1957 J J i s 2,793,267

CONTACT CONSTRUCTION Filed Sept. 29, 1955 2 Sheets-Sheet 1 W 5/ I: W

2 Shets-Sheet 2 Filed Sept. 29, 1 955 Unired States Patent "ice CONTACT CONSTRUCTION JohnJ. Mikos, Highland Park, lll., assignor to S & C

Electric Company, Chicago, 111., a corporation of Delaware This invention relates, generally, to the construction of electrical contacts and it has particular relation to the construction of line contacts for use in the housing of a bayonet type fuse cutout. It constitutes an improvement over the contact construction shown in U. S. Patent No. 2,591,949, issued April 8, 1952.

The bayonet type fuse cutout of the above patent employs a tubular porcelain housing provided with a line terminal contact assembly at each end for engagement by terminals of a fuse tube. Each such contact assembly includes a cylindrical contact sleeve and a surrounding retainer sleeve to which a line conductor fitting is secured. The latter has a cylindrical opening therethrough in alignment with openings in the porcelain housing through which line conductors can be inserted to be held in place by set screws extending transversely of the cylindrical opening in the line conductor fitting.

As a result of increase in load applied to this type of cutout and the use of aluminum line conductors in addition to copper, it has been found that there should be an increase in the area of contact engagement with the line conductors in order to reduce heating and increase the useful life of the device. Because of space limitations imposed by the porcelain housing, it has not been feasible merely to increase the size of the line conductor fittings and employ a larger number of set screws for clamping the line conductors in place. Other means were developed as will appear hereinafter.

Among the objects of this invention are: To increase the current carrying ability of the line terminal contact assemblies of a bayonet type fuse cutout without increasing the size of the porcelain housing on which such assemblies are mounted; to increase substantially the area of contact engagement with the line conductors; to receive difierent diameters of line conductor at the same time; to employ pressure bar's operated by pressure bolts for contacting the line conductors and clamping them in place in the line contact assemblies; to accommodate both copper and aluminum line conductors; to provide a universal connection between the pressure bar and the pressure bolt associated therewith; to form the universal connection by heading over the inner end of a pressure bolt within its pressure bar while permitting freedom of movement therebetween; to provide the universal connection by employing a pair of roll pins in a pressure bar to interengage a necked down inner end of its pressure bolt; and to form the terminal lug carrying the pressure bars and pressure bolts integrally with the retainer sleeve.

Other objects of this invention will, in part, be obvious and in part appear hereinafter.

This invention is disclosed in the embodiments thereof shown in the accompanying drawings and it comprises the features of construction, combination of elements and arrangement of parts that will be exemplified in the constructions hereinafter set forth and the scope of the application of which will be indicated in the appended claims.

Fateiited May 21, 1957 For a more complete understanding of the nature and scope of this invention reference can be had to the following detailed description, taken together with the accompanying drawings, in which:

Figure 1 is a view in side elevation of a bayonet type fuse cutout in which the present invention is embodied;

Figure 2 is a view, partly in side elevation and partly in vertical section, showing the application of one embodiment of the invention to a bayonet type fuse cutout;

Figure 3 is a view, partly in vertical section and partly in side elevation, showing in further detail how the first embodiment of the invention is employed in the cutout housing;

Figure 4 is a vertical sectional view of the fuse which forms the principal part of the bayonet member that is inserted in the housing shown in Figure 3;

Figure 5 is a horizontal sectional view taken generally along the line 5-5 of Figure 3 and showing only the lower line terminal assembly;

Figure 6 is a view, taken generally along the line 6-6 of Figure 3, and showing only details of construction of the lower line terminal assembly;

Figure 7 is a view, in side elevation, of one of the terminal lug assemblies;

Figure 8 is a longitudinal sectional view of a higher ampere rating housing for use with line terminal assemblies having a higher ampere rating than that for which the construction shown in the preceding figures is adapted;

Figure 9 is a horizontal sectional View taken generally along the line 99 of Figure 8 and showing only details of construction of the lower line terminal assemy;

Figure 10 is a vertical sectional view taken generally along the line 1010 of Figure 8 and showing only details of construction of the lower line terminal assembly; and

Figure 11 is a vertical sectional view taken generally along the line 11--11 of Figure 10.

Referring first to the embodiment of the invention illustrated in Figures 1-7 and particularly to Figure 1. it will be observed that the reference character 10 designates, generally, a bayonet type fuse cutout constructed generally as disclosed in the above mentioned patent. The cutout 10 is arranged to be mounted on a cross arm 11, or the like, by a clamp bracket, shown generally at 12. The clamp bracket 12 is connected by an intermediate bracket 13 to a mounting bracket 14 which surrounds the central portion of a tubular porcelain housing 15 which is corrugated to provide increased creepage distance over its external surface as is well understood. Near the ends of the porcelain housing 15 are upper and lower line conductor openings 16 and 17 which extend transversely through the housing and permit the insertion of conductors from either side.

As shown in Figures 2, 3 and 4 of the drawings a handle 18 is mounted at the upper end of a bayonet type fuse, shown generally at 19, that is arranged to be inserted in the porcelain housing. The bayonet type fuse 19 is provided with upper and lower cylindrical contacts 20 and 21 at the ends of a fuse tube 22. The upper cylindrical contact 20 is threaded at 23 for receiving the handle 18. Within the fuse tube 22 i a spring and cable assembly, shown generally at 24, which extends from the upper cylindrical contact 20 and has a fuse link 25 connected thereto at its lower end. The fuse link 25 has a cone terminal 26 which engages a tubular projection 27 can semi-circular extension 28 from the lower cylindrical contact 21. The upper and lower cylindrical contacts 20 and 21 on the fuse tube 22 are arranged to have contact engagement with upper and lower line terminal assemblies 30 and 31 which are mounted at the respective ends of the porcelain housing 15, as shown more clearly in Figures 2 and 3 of the drawings. These line terminal assemblies 30 and 31 are provided with cylindrical contact sleeves 32 and 33 that are arranged to engage directly with the cylindrical contacts 20 and 21. Surrounding the contact sleeves 32 and 33 are cylindrical retainer sleeves 34 and 35 which are secured by cement 36 and 37 to the respective ends of the porcelain housing 15 as described in more detail in the patent above referred to. An insulating liner 38 in the form of a sleeve of insulation is interposed between the upper and lower line terminal assemblies 30 and 31 in order to protect the inner surface of the porcelain housing 15 from any are that might be drawn when the bayonet type fuse 19 is withdrawn under load and for assisting in extinguishing such arc.

It will be understood that the line terminal assemblies 30 and 31 are arranged to be connected to line conductors which are inserted through line conductor openings 16 and 17 in the porcelain housing 15. The present invention has to do particularly with the means for connecting these line conductors to these line terminal assemblies in such manner as to provide increased contact engagement and to accommodate conductors of aluminum as well as conductors of copper.

The details of the improved construction are illustrated more clearly in Figures 5, 6 and 7 of the drawings. As there shown a terminal lug assembly, indicated generally at 42, is provided. The same terminal lug assembly 42 is applied to both the upper and lower line terminal assemblies 30 and 31. Accordingly, it will be described only with reference to the lower line terminal assembly 31. The terminal lug assembly 42 comprises a terminal lug 43 that is formed preferably of an aluminum bronze alloy by a shell molding process. This alloy has high strength and is not subject to stress corrosion or to corrosion cracking. The shell molding process is used for reasons of economy, Sandcasting and subsequent machining can also be used but at a higher cost.

After formation, the terminal lug 43 is tin plated to accommodate aluminum as well as copper conductors. The terminal lug 43 has an arcuate portion 44 which fits around the intermediate portion of the cylindrical retainer sleeves 34 or 35 as the case may be and is secured thereto by rivets 45 which project also through the cylindrical contact sleeves 32 or 33.

For receiving the line conductors the terminal lug 43 is provided with an oblong opening 46, Figure 7, which extends entirely therethrough and is positioned in alignment with the respective line conductor openings 16 or 17. As seen in Figure 7 the lower end of the oblong opening 46 is flat as indicated at 47, while the upper end is formed by arcuate surfaces 48 and 49. These surfaces have different radii as indicated at 50 and 51. The smaller radius 50 for the surface 48 is located with the center above the center for the larger radius 51. This locates the arcuate surface 48 between portions of the arcuate surface 45 and thus provides for receiving different diameters of conductors, such as the conductors 52 and 53, Figure 6, in intimate contact engagement. For example, the terminal lug assembly 42 is arranged to receive and provide intimate contact engagement with conductors ranging from a diameter of .128" to .328.

With a view to securing the conductors 52 and 53 in the respective terminal lug assembly 42 and providing intimate contact engagement therewith pressure bar 54 are employed. These pressure bars are formed preferably of copper and are tin covered preferably by hot tin dipping to accommodate aluminum as well as copper line conductors. The hot tin dipping of the pressure bars provides a relatively thick film of tin over the copper pressure bars 54 which is not easily pierced and which slides readily relative to the conductors because of the lubrieating action provided bythis method of coating. Each of the pressure bars 54 has a concave surface 55 for overlying substantially a semi-circular portion of the respective conductor 52 or 53.

As shown in Figure 6 each pressure bar 54 has a small diameter opening 56 on the side opposite the concave surface 55 provided with a shoulder 57 connecting it with a large diameter opening 53. A neck portion 59 of the pressure bolt 69 extends through the small diameter opening 56 and it has a headed over portion 61 within the large diameter opening 58. The neck portion 59 is inserted through the small diameter opening 56 and then a suitable peening tool is inserted through an opening 62 for heading over the portion 61 after the pressure bolt 60 has been threaded through a wall 63 which forms a part of the terminal lug 43. While the headed over portion 61 prevents detachment of the pressure bar 54 from the pressure bolt 66 after assembly, the construction is such that the pressure bar 54 is relatively loosely mounted on the pressure bolt 69 and thus a universal connection is provided therebetween which permits some degree of freedom of movement between the pressure bar 54 and the pressure bolt 60.

In operation'it will be understood that conductors 52 and 53 of different diameters can be connected to each of the line terminal assemblies 35 and 31 as may be desired. Of course two conductors of the same diameter can be so connected. In the event that only a single condoctor is to be connected to one or both of the line terminal assemblies 30 or 31 it would be inserted through the respective opening 16 or 17 in the porcelain housing 15 and then between both of the pressure bars 54 and the arcuate surfaces 48 and 49 to the end that both pressure bars 54 would have contact engagement therewith and thus provide a relatively great area of contact engagement therewith. The universal joint connections between the pressure bars 54 and the respective pressure bolts 60 permit the former to seat properly against the line conductor or conductors, as the case may be, and provide intimate contact engagement therewith.

In Figures 811 a higher ampere rating construction for the bayonet type fuse cutout is shown. Only the housing and line terminal contact assemblies are. illustrated, the bayonet member including the handle and the.

fuse being generally similar to the handle 18 and the fuse 19 described hereinbefore but of somewhat larger size.

As shown in Figure 8 a porcelain housing 65 is employed which corresponds to the porcelain housing 15 previously described. The porcelain housing 65 is provided with corrugations between its ends for increasing the creepage distance. Near its ends upper and lower line terminal assemblies 66 and 67 are provided corresponding to the line terminal assemblies 30 and 31 previously described. The line terminal assemblies 66 and 67 include cylindrical contact sleeves 68 and 69 that are surrounded by cylindrical retainer sleeves 70 and 71. In this instance the cylindrical retainer sleeves 7t and 71 are formed integrally with a terminal lug 72 by a.

shell molding process. Since the same construction is cracking or stress corrosion. process was used for reasons of economy although sand casting and machining can be used. 1

As shown in Figure 11 an oblong opening 73 is provided through each of the terminal lugs 72 in alignment f with line conductor openings 74 and 75 near the ends of the porcelain housing 65. As shown the upper and lower ends of the oblong openings 73 are generally semicircular. Movably'mounted within the oblong opening.

73 are two pressure bars 78 that are formed preferably of copper and are tin covered preferably by hot tin dipping in order to accommodate aluminum as well as copper line conductors as outlined herebefore for the pressure bars 54. Each pressure bar 78 has a concave surface for engaging line conductors 80 and 31 which, as shown in Figure 10, can be of different diameters. For example conductors ranging in diameter from .162" to .447 can be accommodated.

The pressure bars 78 are moved into good contact engagement with one or both of the line conductors by pressure bolts 82. The inner ends of the pressure bolts 82 are reduced in diameter as indicated at 83 and are provided with necked down or annularly grooved portions 84 for projecting into an opening 85 in the side of the respective pressure bars 78 opposite the concave surface 79 for interengagement with roll pins 86 which extend longitudinally of each pressure bar 78. The pressure bolts 82 are threaded through a wall 87 of the terminal lug 72 and then the pressure bars 75 are positioned on the reduced diameter ends 83. Thereafter the roll pins 86 are inserted through the respective pressure bars 78 to hold them inseparable with respect to the pressure bolts 82. At the same time a universal joint connection is provided therebetween which permits some freedom of movement of each pressure bar 78 with respect to its pressure bolt 82. This facilitates seating against the line conductor and provides intimate contact engagement therewith over a relatively large surface. At their outer ends the pressure bolts 82 can be provided with hexagonal heads 88 for receiving a socket Wrench and they also can be provided with slots 39 for receiving a screw driver.

In operation it will be understood that two conductors of different diameters can be connected to each terminal lug 72 as shown in Figure 10. Also two conductors of the same diameter can be so connected. In the event that a single conductor is connected to the terminal lug 72, it is positioned therein so that both of the pressure bars 78 can engage and clamp it in position.

Since certain further changes can be made in the foregoing constructions and different embodiments of the invention can be made without departing from the spirit and scope thereof it is intended that all matter shown in the accompanying drawings and described hereinbefore .6 shall be interpreted as illustrative and not in a limiting sense.

What is claimed as new is:

l. A contact construction for mounting at the end of a tubular porcelain insulator or the like for receiving a cylindrical terminal of a bayonet type fuse and connecting the same to line conductors extending through transverse openings in said insulator, said contact construction comprising, in combination, cylindrical contact means for engaging internally said cylindrical terminal and adapted externally to be secured in said insulator; and a terminal lug assembly including a terminal lug mounted externally on said cylindrical contact means and having a generally oblong opening therethroug'n aligned with said openings in said insulator, two pressure bars freely slidably mounted in said oblong opening and each having a concave contact surface along one side for engaging a conductor between it and the opposite side of said oblong opening, and a pressure bolt threaded in said terminal lug and having a universal connection to each pressure bar for clamping said conductor between said contact surface and said opposite side of said oblong opening.

2. The invention, as set forth in claim 1, wherein the terminal lug is tin plated and the pressure bar is hot tin dipped to accommodate copper and aluminum conductors.

3. The invention, as set forth in claim I, wherein the opposite side of the oblong opening is formed by two arcuate surfaces of different radii with the surface having the smaller radius being directly opposite the concave contact surface on the pressure bar and intermediate two sections of the larger radius surface.

4. The invention, as set forth in claim 1, wherein the universal connection between the pressure bar and the pressure bolt is formed by a pair of roll pins extending in parallel spaced relation lengthwise of the former and interengaging a necked down portion on the latter.

References Cited in the file of this patent UNITED STATES PATENTS

Images