US1730180A - Insulator - Google Patents

Description

Oct. 1, 1929. N. A. WAHLBERG INSULATOR Filed May 11, 1927 INVENTOR Nils A.Wahlberg ATTORNEY WITNESSES:

Patented Oct. 1, 1929 UNITED STATES PATENT OFFICE NILS A. WAHLBEBG, OI WILKINSBUBG, PENNSYLVANIA, ASSIGNOR '10 WESTING- HOUSE ELECTRIC 8: MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA nvsumrron Application filed Kay 11, 1927. Serial 110. 190,417.

My invention relates to insulators and particularly to high-voltage transmission-line insulators. v

One object of my invention is to'provide an insulator, of the above-indicated character, that shall embody a reinforcing or holding member of such construction and disposition relative to an insulating member and a metal terminal member therefor, as to permit the latter to -b constructed of cast metal, such as'aluminum.

Another object of my invention is to provide an insulator terminal structure, embodyinga wall or sheet portion of relatively great expanse, that shall be effectively braced and reinforced, at its position of mounting, to prevent tilting thereof relative to the insulator and that shall be otherwise constructed to maintain the same rigid.

Another object of my invention is to provide an insulator embodying an insulating column unit free of extensive lateral projections intermediate its ends and readily removable terminal units therefor, including annular electrostatic-field-control portions of relatively great diameters in which the disassembled column and terminal units of a effective cementing cooperation between tension elements, such as porcelain and aluminum, which are ordinarily not readily adapted for such cooperation.

Another object of my invention is.to provide aninsulator that shall embody upper and lower elements for causing an annular, and widely distributed, electrostatic field of greatest intensity around, and spaced from,

the insulator within the outer perimeters of the elements, in which the lower element is imperforate and capable of shedding rain.

A further object of myinvention is to provide a high-voltage insulator structure that shall be simple and durable in construction, economical to manufacture and effective in its operation.

In a copending application, Serial No. 548,818, filed April 1, 1922, by H. B. Smith and assigned to the Westinghouse Electric and Manufacturing Company, is set'forth an insulator of which this invention is an improvement, and to which application reference may be had for a better understanding of the present invention. In general, the insulator operates on the principle of both widely distributing the electrostatic field and causing it to assume the form of a'hollow cylinder, in the sense that the walls of the cylinder are comparatively thick and of low intensity and the center of the cylinder, next to the insulating surface, is of negligible intensity.

This principle requires the use of terminals or electrostatic-stressdistributing members of relatively great area, which it is desirable should be as light in weight, and as strong, as possible.

To obtain these features, it. has heretofore been suggested to construct the terminals of spun or pressed sheet metal, such as copper, or to make them of insulating material with a foilor other metal coating.

Also, by reason of the peculiar configuration of the insulator constructed of a column that is free of extensive lateral projections intermediate its ends and is provided with end toroids or terminals of relatively great diameter, the shipment thereof in an economical, effective and safe manner becomes a problem of appreciable concern.

In view of the importance of the art to which the invention relates, and the particularly arduous service for which the insulator is intended, every feature of operativeness, strength and economy must receive careful consideration, and it is to this end that the present invention is proposed.

In practicing m invention, I provide electrostatic-stress- 'stributing and directing terminals that, while of relatively thin sheet formation, are constructed by casting and are so formed and reinforced at a position of greatest mechanical stress, as to prevent'tilting or bending of the parts, relative to the insulator and to each other. These features permit the use of a very lightweight material, such as aluminum, in a manner to permit it to be effectively cemented to porcelain and to provide an insulator that retains its parts in accurate relation to each other and is, in general, a marked improvement over prior suggestions.

Also, the insulator is so constructed of readily detachable insulating column and metal terminal units that, in shipping large numbers of similar insulators, the upper terminals may be nested one within another, the columns may be packed in relatively close parallel relation and the lower terminals may be stacked or nested, thus conserving space and expense and rendering the shipping operation safer and more expeditious.

Figure 1 .of the accompanying drawings,

is a view, partially in elevation and partially in section, of an insulator constructed in accordance with my invention, and

Fig. 2 is a similar View of a modified form thereof.

Referring to Fig. 1, the device comprises, in general, an insulating column rod or tube 2, an upper terminal structure 3 and a-lower terminal structure 4.

The tube or rod 2 is preferably constructed of refractory material, such as porcelain or glass, although impregnated wood, paper, cloth or any other suitable material may be employed.

If of porcelain or smiliar material, the

' cylindrical end portion of the rod may be sanded or otherwise roughened or prepared for effective holding cooperation with cement and, if of glass, the ends may be etched, serrated or otherwise treated for such purpose. In the structure illustrated, the tube 2 is of porcelain having sanded ends to which are permanently secured or cemented metal closure cap or cup members 6 and 7, constituing elements of the upper and lower terminals 3 and 4, respectively. These caps are preferably of drop-forged iron which is of known strength and ability for effective holding cooperation with Portland cement.

The caps are also preferably ungalvanized, particularly on the inner surfaces next to the cement, but may be galvanized on the outer surfaces thereof.

The upper terminal structure 3 further comprises a relatively extensive combined hood and holding member 8 having parts 10, 11, 12, 14, 15 and 16 all integrally united as one homogeneous unit and each having a particular function cooperating with the others.

The part'10 is a holding clevis, for which a ball or a socket of a ball-and-socket connector or other suitable device may be subeted or otherwise connected to provide better a holding cooperation therebetween than might be effected directly between the cement and the cap 11 which. is preferably of aluminum. However, the screw-threaded arrangement shown, or other arrangement whereby the member 8 may be readily removed-from the tube or column 2, is preferred.

The part 12 is of relatively deep bowl shape and merges very gradually, through the widely-curved portion 14, into the portion 15. The latter is in the form of a relatively wide band or rim about the bowl portion 12 and, in contradistinction to the part 12, is of considerably less, or only slight, in clination to the horizontalor to a line normal to the longitudinal axis of the rod 2.

The portion 16, in theform of an annular head or rib, serves the double function of water-drip portion and reinforcement against radial crushing or bending.

The part 12 is also, preferably jointed to .the cap 11 by a thickened, and graduallycurved, portion 18 in the position at which exists the greatest tendency for the other relatively expansive parts to pivot or bend out of true relation to the insulator axis.

The lower terminal structure 4 further comprises a cap portion 20 and an eye portion 21, similar to the cap and clevis portions 11 and 10, respectively, and for similar attachment to the cap or cylinder 7, and

a hood or toroidal portion 22. The latter,

similarly to the upper terminal structure 3, has a portion 24 of sheet-like formation joined to the cap 20 by a thickened and curved portion 25 and a combined waterdrip and reinforcing annular bead or rib 26. In the above-described structure, a line :12 marks the position of greatest electrostaticfield intensity, and although referred to as of greatest intensity is in reality of greatly reduced intensity compared to insulators of other types. In other words, in any insulator there must be a position or zone of ultimate arc-over and, in-this instance, this zone is caused to be as weak as possible in order to get the full insulating value of the. materials employed.

The terminal parts adjacent to this zone,- which is annular or cylindrical in form about the longitudinal axis of the rod 2, re-

cede longitudinally. and radially therefrom so that, at a position adjacent to the surface of the rod 2 and at a position adjacent to the water- drip portions 16 and 26, the field is almost negligible in strength.

These features reduce surface current formation alon the rod and prevent the introduction o conducting rain water into the field at a place where breakdown of the field might result therefrom.

In suggestions heretofore made, and as shown in Fig. 2 hereof, the lower terminal 4 has been depressed, or hollowed out, at its upper central portion adjacent .to the rod 2, but, in thisinstance, the dimensions are so chosen as to obtain substantially the effect of the hollowed terminal. This feature may be seen by taking the upper end of the line a: as a pivot point and swinging the lower end of the line left and right as viewed in the drawing. If this be done, it is seen that the lower end of the line a:, as shown, is at substantially its shortest touching distance on the lower terminal and assures that ultimate arc-over will occur substantially along the line and that the field is weaker on each side thereof.

This feature provides water drainage for the rod and lower terminal, without perforating the lower terminal, and permits a structure of better casting or construction character to be obtained.

In the above described structure, the features of forming the parts, as shown, and casting them as single integral or homogeneous parts of aluminum or other suitable material, are believed to be material steps in advancing and promoting progress in the important field of increased commercial transmission line Voltages, to attain which every eifort'is being made.

In the form of my invention shown in Fig. 2, in which corresponding parts are designated by corresponding reference characters, the construction is substantially the same, with'the exceptions that the bowl portions 12 of the upper terminal 3 is joined to the cap 11 at a lower position thereon and the portion 24 of the lower terminal 4 is disposed above the cap 20 and requires drainage openings 30. I

In'either form, there are only three readily separable and attachable units, one of which is the column 2 with the caps or end closure members 6 and 7 permanently secured thereto, another of which is the single homogeneous member 8, including the pa rts or elements 10, 11, 12, 15, Mind 18,

and the third of which is the single homogeneous member or structure 4, including the elements ,20, 21, 22, 24 and 26.

f Hence, in shipping a plurality of such in smators, the above-mentioned units 8 may be nested one within another, the units 4 may be similarly nested or stacked and the column units 2, since they haveno appreciable lateral projections intermediate their ends, may be packed or crated in relatively close parallel relation, thus conserving a very great amount of space and facilitating and economizing the shipping operation to a; I

higlvih egree.

ile I have shown and described particular forms of my invention, changes may be effected therein without departing from the spirit and scope thereof, as set forth in the appended claims.

I claim as my invention:

1. An insulator comprising an insulating column free of extensive lateral rojections intermediate its ends, metal end members permanently secured thereto, an upper electrostatic-field-control hood of relatively great diameter compared to the length of. the column readily removably secured to one of said end members and a lower annular fieldcontrol member of smaller diameter than the hood readily removably secured to the other end member, the arrangement of parts permitting shipment of a lurality of disassembled similar insulators y nesting the hoods, stacking the lower field-control members and placing the columns in relatively close parallel relation to each other.

2. An insulator comprising an insulating column free of extensive lateral projectionsintermediate its ends,externally screw-thread ed metal sleeves permanently secured in position around said ends, an upper electrostatic-field-control hood having an internally-screw-threaded portion for cooperation with one of said sleeves and a lower annular field-control member of smaller diameter than the hood having an internally-screw threaded portion for cooperation with the other sleeve.

3. An insulator comprising an insulating column free of extensive lateral projections intermediate its ends, externally screwthreaded metal sleeves permanently secured in position around said ends, a single homogeneous upper member including an electrostatic-field-control hood portion, an internally-screw-threaded portion for cooperation with one of said sleeves and a portion for mounting the insulator, and a single homogeneous lower member including an annular field-control portion of smaller diameter than the hood, an internally-screw-threaded portion for cooperation with the other sleeve and a portion for attaching an object to the lower end of the column.

4. An insulator comprising a tubular insulating column, metal end-closure members therefor permanently secured thereto, and means for readily-removable attachment as a unit to each of said end-closure members in cluding an electrostatic-field-control portion and a portion for attaching the insulator to another object.

5. An insulator comprising a tubular insulating column, metal end-closure cups permanently secured in telescopic relation over the ends of the column, said cups having exteriorly-screw-threaded side surfaces, and

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means for readily-removable attachment as a unit to each of said cu s, the upper of said means'including a hoe portion of relatively great diameter compared to the length of the column, an internally-screw-threaded central sleeve portion and a portion for mounting the insulator, and the lower of said means ineluding a field-control torus of smaller diameter than said hood, an internally-screww threaded central sleeve portion and a portion for attaching an object to the lower end of the column. In testimony whereof, I have hereunto subscribed my name this 29th day of April, 1927. NI LS A. WAHLBERG

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