US1728952A - Conductor terminal for bushings - Google Patents

Description

Sept. 24, 1929. Q AUS'HN 728,952

CONDUCTOR TERMINAL FOR BUSHINGS Filed July 29. 1922 A [AIVENTOR BY {fi E ATTORA/EY having an end cap 2 assembled therewit li atentesl t. 2

ARTHUR (Cl. AUSTEN, 15 QEEQ'ASQIGHQR, BY ASSEGNZEENQE,

THE @HEU BRASS oorrirarrr. 632m), A

JER$EY GUN TC! CGBJWRATIUN GE" son assumes Application filed July 28, Serial 130. 523,462

This invention relates to terminal construction for insulator bushings such as are used in connection with transformer housings and other installations where insulator bushings are used. The invention has for its object the provision of a terminal construction in which a low resistant electrical contact is secured, in which the bushing may he removed or installed Without disturbing the connections within the housing, which shall exclude moisture from the interior of the hushing and which shall contain other improved features or? construction and operation which shall appear hereafter.

The invention is exemplified hination and arrangement of parts sl the accompanying drawing and descrihed in the following specification. and it more particularly pointed out in the appended claims.

In the drawing Fig. l is elevation and part section view showing one einhodiment of the present invention.

Fig. 2 is a section on line 2-2 1. As illustrated in the drawing. the numeral 1 designates a bushing of dielectric rraterial h and provided with a gasket 3 and cement for forming a tight connection hetween end cap and hushin A conductor 5 extends thru the opening 6 in the bushing and has a square or other angular form 7 secured thereto by brazing soldering or other ap roved method of attachment The lug 7 orrns a continuation of the conductor 5 and has its outer end reduced and threaded as shown at 8,thus forming shoulder 9 at the inner end of the threaded portion. The endcap 2 has an upwardly extending flange 10 provided with an angular opening 11 therethru for receiving the angular portion of the lug 7. Above the opening 11 is a shoulder 12 having an opening for receiving the threaded end 8 of the conductor 5 by providing'an abutment for the shoulder 9 to limit the upward movement or the conductor. The nut 13 is threaded on the end 8 the conductor and is screwed down against the upper surface of the flange it) to clamp the portion 12 thereof hetwecn the shoulder downwardly extending flange 16 provided with a yielding gasket it? below the lower oi the tlange and the top surface of the cap- 2; this will permit the cap it to he screwed down until it is stopped by the hearing and at the same time will compress the gasket to form a tight joint. the cap is t -us tightened it will exert an upstress on the threads 8 us in sure close contact between the threaded surfaces on the conductor and terminal or the purpose of providing low resista'" trical connection between these parts. further insure close contact between the threaded surfaces, a helical spring 18 racy Le interposed hetween the closed end cap upper end of the threaded conduct-or 8. This spring will "exert pressure on the cap conductor drawing upwardly Q on the cap and pressing downwardly on the conductor, thus augmenting the action of abutment surfaces which hold the cap and conductor. The spring 13 will also serve the function of a lock washer for preventing loosening the cap on the conductor. A. 866GB d spring 19 may be interposed between the cap and the nut 13 to assist the spring 18 in a sirn way. A conductor lead 20 is provided with a lug 21 secured to the end a thereotin any approved manner, and having a tapered suriface 2Q For engagement with a corresponding surface on a screw clamp or [or 23 for connecting the lead the ter nal cap .i very good hearing or electrical contact can he obtained hetween the upper end of the conductor 8 and the Weather cap ll, as all the stress is taken up between the metal parts. This has the advantage, in that the below without being broken.

shrinking of the gasket Will not affect the electrical contact and, in addition, thermal expansion is not so likely to loosen the joint.

tion is prevented by the squared section 7 which engages ina suitable recess 11 in the cap. When the weather cap 14 is drawn down tightly the squared section 7 bears against the shoulder 12 in the cap 2. This prevents the lead from being drawn thru the bushing, and when the cap 14 is then tightened, pressure is exerted between the cap 2 and the cap 14 at the shoulder 15 and between the cap 2 and the lug 7 at 12. If a ground joint is provided, this will insure a tight fit, or a gasket may also be used.

A preferable method, however, is to install a metal gasket at the point 15 or a soft gasket at the point 17. If a tight joint is not necessary, these gaskets may be left out as the cap 14 provides a water shed so that water cannot drip into the transformer or device upon which the bushing is used. I This form of terminal has the advantage, in that, a flexible conductor 5 may be used. This type of terminal also has the advantage, in that, it may be applied to practically any bushing to which the form of cap shown in Q may be attached, as no. special recesses are required in the bushing. The cap 23 provides means for connecting the external lead 20. Electrical contact is insured by the lug 21 and the upper face or the cap at the-surface 25. This may be a fiat sur-- face or may be conical to provide increased contact area. To insure a good electrical contact, a thin layer of tin or a springing material such as wire gauze, or corrugated disk is used in the joint. Further electrical contact is provided at the surface 22. This contact surface is'increased by making same conical.

As all stress necessary to make good clectrical contact or to make tight joint is confined at the top of the bushing a conductor 5 either rigid or solid may be used with a suitable insulating covering which may extend well up into the bushing and Tlhis-covering reinforces the bushing and tends to prevent electrical discharge Where the conductor leaves the lower end 0 5 the bushing, particularly if the oil level is low or the bushing is installed above oil level. The insulating covering may permit the use of a shorter and cheaper bushing, as the covering is very effective in preventing a discharge to ground or other conductors for surges of high magnitude and short duration. If the covering to be broken at the lower end of the bushing, thi covering would be difficult to insulation.

make and still insure a suflicient degree of With the bushing terminal as shown, a fiber tube or varnished cambric coverings may be used which are inexpensive and easily installed.

This type'of terminal is generally used where a high degree of tightness is not essential to prevent leakage of oil or air, but where it is highly important to keep out rain. This condition is found in general practice where the oil level in the transformer or conservator is not abovethe top of the bushing.

I claim:

1'. A dielectric bushing having a metallic fitting secured thereto, a conductor in said bushing, means for clamping said conductor tosaid fitting and a terminal cap for said conductor threaded on the projecting end thereof and bearing against said fitting.

2. A dielectric bushing, a metallic fitting secured to said bushing, a conductor extending through said fitting, a nut for clamping said conductor to said fitting and a terminal member threaded on said conductor and bearing against said. fitting so that the force of said conductor and terminal member caused by tightening said terminal member will be transmitted to said fitting.

3. A dielectric bushing having a metallic fitting rigidly fixed to one end thereof, a conductor having an end portion thereof passing through an opening in said fitting and having a shoulder engaging said fitting for limiting outward movement oi' said conductor through said fitting, the minimum diameter of said opening being greater than the maximum diameter of said end portion to permit passage of said end portion through said opening Without relative rotation of said fitting and conductor, a terminal cap threaded on the projecting portion of said conductor and having bearing against said fitting to draw said conductor to the position to which it is limited by said shoulder, and a gasket interposed between said terminal cap and litting at a position removed from said hearing, and forming a tight joint to close the opening in said bushin i. A dielectric bushing having metallic fitting secured thereto, a conductor extending freely through said bushing and fitting, means on said fitting for limitin movement of said conductor therethrough, terminal member threaded on said conductor to hold said conductor against said limiting means and a spring interposed between said conductor and terminal member and exerting opposite forces on said conductor and terminal member to provide close contact between. their threaded surfaces.

5. A dielectric bushing hav'in a metallic fitting secured thereto, a conductor extending loosely through said bushing and fitting, a shoulder for limiting outward movement of said conductor relative to said fitting, a

terminal member threaded on said conductor and bearing against said fitting to exert outward force on said conductor thus insuring close connection between the threaded surfaces of said terminal member and conductor, and a spring interposed between said terminal member and conductor for augmenting the force tending to hold said threaded surfaces in close connection.

6. A dielectric bushing having an opening therethrough, a metallic fitting secured to said dielectric bushing, a conductor having a threaded portion extending through said fitting, a nut for clamping said conductor to said fitting and a terminal member threaded on said conductor and bearing against said,

fitting to exert force on said-conductor, said terminal member having clearance to permit rotation thereof independently of said nut.

7. A dielectric bushing having a metallic fitting secured thereto, a conductor assing through said bushing, means for clamping said conductor to said fitting, a terminal cap threaded on the projecting portion of said conductor and bearing against said fitting, a

spring interposed between said cap and the end of said conductor tending to move said conductor and terminal cap relative to each other to produce close contact between their threaded surfaces, and a second spring interposed between said terminal cap and clamping means for augmenting the action of said first mentioned spring.

8. A dielectric bushing having a metallic cap secured to the top thereof, a conductor extending through said bushing and having an angular portion fitting a similarly shaped opening in said cap and an imperforate cover threaded on said conductor and bearing on said cap to form a seal for said bushing and to provide electric contact with said conductor, the stress produced by said bearing being entirely confined to the capand parts mounted thereon.

In testimony whereof I have signed my name to this'specification on this 25th day of July, A. D. 1922.

1 ARTHUR O. AUSTIN.

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