US1977808A - Pothead terminal - Google Patents

Description

Oct. 23, 1934.

Filed Jan. l2. 1932 2 Sheets-Sheet. l4

ATTO R N EYS Oct. 23, 1934.

E. F. Wl SALISBURY ROTHEAD TERMINAL 2 Sheets-Shee Filed Jan. l2, 1932 l Il x.

ATTORNEYS Patented Oct. 1934 i UNITED STATES PATENT OFFICE 'to Anaconda Wire &

Cable Company, New

York, N. Y., a corporation of Delaware Application January 12, 19:2, serial No. 586,168

4 Claims.

'I'his invention relates to improvements in terminals for electric conductors and in particular to what is known in the art as a pothead terminal.

The invention will be fully apparent from the v following detailed description when read in connection with the accompanying drawings and will be pointed out with particularity in the appended claims.

In the 'drawingsz- Fig. 1 is a longitudinal vertical section through a pothead embodying the invention;

Fig. 2 is a detail view illustrating the manner of assembling parts ofthe pothead terminal of Fig. 1;

Fig. 3 is a horizontal section taken on line 3-3 of Fig. 1;

Fig. 4 is a vertical section similar -to Fig. 1, but illustrating a modification of the invention.

Referring in detail to the drawings, represents any fixed structure, to which a pot or casing 12 is secured by means of bolts 14. The lower extremity of the pot 12 is of substantially hollow frusta-conical form, as indicated at 16 andit has an axial aperture 18 at its extremity of a diameter siimciently large to permit the entrance of the enlarged parts secured to the end of the terminal to be hereinafter referred to.

At the top of the body, there is formed a flange 20 having a counter-sunk portion, in which is seated a gasket 22 formed of cork, or the like.

A shoulder 24 formed on an insulator l26 is seated on the gasket 22. This insulator has a downwardly extending skirt portion 28, which makes a loose fit with the bore 30, at the upper part of tion 24 and also extending fora short distance upwardly there is a pad 32 formed of fabric, or other suitable resilient material.

For detachably securing the insulator 26 to the body or casing, I provide a two part base ring, indicated as a whole at 34. This ring, as best shown in Fig. 3, includes two substantially semicircular parts 36 and 38, which aresecured to one another by transversely extending screws 40. Each of these rings, is provided with a plurality of lugs 42 adapted to receive the ends of bolts 44 which pass through the flange 20 of the pot or casing, thus drawing the shoulder 24 of the insulator rmly against the gasket 22 seated on the flange of the pot or casing 12. l

The insulator 26 is provided with an axially extending, interior chamber 46 having a diameter sufllciently large to permit the free passage of the enlarged pothead terminal to be presently referred to.

the pot or casing. Surrounding the shoulder por-V (cl. 17a-asa) An electric conductor 48usua1ly in the form of a stranded cable has secured to its terminal portion 50 a stem member, indicated as a whole at 52. This member has an interior socket 54 into which the extremity of the terminal portion 50 of the cable is securely fastened, the joint usually being made permanent by soldering. The lower extremity of the stem 52 is in the form of an enlarged head 56 having screw threads on the exterior thereof, which engage threads 58 formed 55 on the interior vof a tube or sleeve 60, formed of bakelite, ber, or similar dielectric material.

The cable 48 is wrapped with a plurality of layers of suitable insulating material in any manner well known in the art. This insulator wrapping being indicated at 62. Over the insulation, there is an outer lead sheath 64. The upper extremity of this sheath is flared outwardly, as indicated at 66, so as to form a seat for the tapered or beveled end of the sleeve 60. The sleeve 60 in its working position is screwed down over theenlargement -56 of the stem 52, so as to seat the beveled portion 68 firmly against the flared part 66 of the sheath. so as to form a hermetical seal. The sleeve 60 is provided with 80 a removable tapered closure plug 70, through which a suitable insulating compound can be inserted after the parts are assembled. This insulating compound, is indicated at 72, in Fig; 1.

, After filling up the void between the interior 35 of lthe sleeve 60 and the exterior of the cable and its wrapping, the tapered plug '70 is nrmlyl screwed home, thus hermetically sealing the terminal portion 50 of the cable.

The'stem 52 above referred tois provided with 90 a flange 74 of non-circular form. As illustrated, this flange is square in plan and it is seated against a similarly shaped gasket or washer 76, bothJ the flange and the gasket being accommodated in a square recess 78 eformed in the in- 95 terior'portion of the insulator. The shank 80 qi.' the stem 52 extendsv freely throughV an enlarged axial opening 82 ofthe insulator body and has Dardelet self-1ocking threads 84 formed thereon. .These threads engage the interior threads formed on the hood mit 86. This nut has a petticoat portion 88, which depends from a bearing portion mi which is adapted to seat against the gasket 92 located on top of the insulator body. The hood nut has aI hexagonal portion 94 adaptedfor engagement with a suit-f able wrench. When this hood nut is screwed on the threads 84 of the shank of the terminal, it will be understood that the squared flange 'Z4 prevents the terminal from turning relatively to 110,

this insulating material is introduced in the form of a liquid, or semi-liquid, or semi-plastic mass, the same being forced in under pressure through an inlet port 104 formerly closed by a tapered pipe plug 106.

'I'o positively prevent leakage of the insulating compound from the lower part of the pot or casing, I provide a cone-like ring or thimble 108, which is attached to the conical portion 16 of the pot. And over the ring, I form a wiped joint 110, this joint of course readily adhering to the llead sheath surrounding the cable.

In Fig. 4, I have illustrated a modification, in which many of the parts are the same as those above referred to and they are, therefore, indicated by like reference characters. The chief diiference between this construction and that shown in Figs. 1 to 3 is that I omit the threaded flange 56 of the terminal stem 52 and also the shell 60. -In this form of device, the lead sheath surrounding the cable terminates at a point below the insulator petticoat 28. This sheath is flared outwardly, as indicated at 112 and it has soldered thereto a stress cone 114 adapted to distribute electrical stress well known in the art.

From the `foregoing, it will be appreciated that in my improved construction Ithe insulator for the pothead terminal is secured to the pot or casing by the two part clamping ring Without the use 'of cement or the like. f

The described construction aims .to eliminate the usual line troubles with potheads which are usually caused by the entrance of moisture at the top of the struc-ture. The herein described structure, precludes the entrance of such -rnoisture, itbeing understood that the clamping action of the hood nut 86 and the flange 74 will hermetically seal the interior of vthe insulator, the gaskets 92 and 78 contributing materially to this desirable end. The self-locking threaded connection between the shank of the terminal stem and the hood nut makes it impossible to loosen the laitter by vibration. The sleeve with its tapered lower extremity makes a substantially moisture .tight joint with the flared part ofthe lead sheath when filled with compound, thusl making a perfectly rtight joint, so that in the event that moisture should ,seep into the pot `or casing due to leakage, or depletion'of the insulating filling, such moisture cannot reach the insulated wrapping around the conductor and thereby.; cause its breakdown. I

The 'above and other inherent advantages of the described pothead terminal will be readily apparent to those skilled inthe art.

While I have described quite precisely the design and construction of certain embodiments of. the invention herein illustrated, it is to be understood that the description and drawings are to be interpreted in an illustrative rather than 'a limiting sense since various modifications may be made by those skilled in the art without departure-from the invention as defined in the appended claims.

What I claim isz- 1. In a device of the character described, a pot-casing having a supporting flange, an insulator, means for securing the insulator to said flange, said insulator having a depending petticoat portion extending downwardly from said flange into the interior of the casing, a sheathed conductor extending through said insulator and having a flared portion spaced from fthe extremity of said petticoat portion, a terminal stem secured rto one end of said conductor, a sleeve of insulating material'threaded on said stem and having a tapered portion for engagement with the iiared part of said sheath, and means for clamping said terminal stem to said insulator.

2. In a device of the class described, a pot-casing, an insulator secured thereto, a sheathed conductor, a joint secured to the casing and said sheathed conductor, a terminal stem secured to anend of said conductor within said insulator, said terminal stem having a sleeve of insulating material threaded on one end thereof, said sleeve having a portion shaped to wedgingly engage a portion of the sheath for the conductor, an abutment on said terminal stem, a gasket interposed between said abutment and part of the insulator body and a nut threaded on the extremity of sai-d shank and having a. hood portion extending across the top thereof.

3. In a device of theclass described, a fptcasing, an insulator secured thereto, a metalsheathed conductor having one end enclosed by said insulator, a joint uni-ting the casing to the sheafth of said conductor, a terminal stem secured to .the end of the conductor within said insulator, said terminal stem having a sleeve `of insulating material threaded thereon, the sleeve having a portion shaped-to wedgingly engage a portion of the conductor sheath, an abutment on said terminal stem, aV gasket interposed between said abutment and part of the insulator body, a nut threaded 'on the extremity of said shank and having a hood portion enclosing 'the top thereof, a conductor having a fitting secured thereto and means for clamping said fitting to said nut.

4. A pothead terminal of the character described including an insulator, an insulated conductor having va metallic protective sheath, a terminal stem clamped to said insulator and secured to said conductor, a sleeve of insulating material in screw .threaded engagement with said stem. and having one extremity in wedged engagement with said sheath, a pot or casing for .supporting said insulator and separable meansv embracing the insulator for securing it to said pot casing. Y i

' EDWARD F. W. SALISBURY.

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