US1684441A - High-tension insulator - Google Patents

Description

Sept. 18, 1928.

M. F. H. GOUVERNEUR HIGH TENSION INSULATOR Filed March 16, 1925 Jwuentoz Patented Sept. 18, 1928.

UNITED STATES PATENT OFFICE.

MINOR F. H. GOUV'ERNEUR, OF BALTIMORE, MARYLAND, ASSIGNOR TO LOCKE INSULA- TOR CORPORATION, OF BALTIMORE, MARYLAND, A CORPORATION OF MARYLAND.

HIGH-TENSION INSULATOR.

Application filed March 16, 1925. Serial No. 15,851.

The invention relates to insulators and more particularly to high tension insulators of the suspension type.

The principal object of the invention, generally considered, is to provide a suspension insulator comprising a cap, a pin and an interposed dielectric, the cap and pin being so positioned and disposed with relation to the dielectric that the line of force emanating from one of said members will be opposed by lines of force emanating from the other, the said lines of force being substantially equal and acting in opposite directions.

Another object of the invention is to provide a suspension insulator of the cap and pin type which will have a high combined electrical and mechanical strength so as to adapt the same to modern service conditions.

To these and other ends the invention comprises the various elements and combinations of elements hereinafter set forth.

In the drawing the figure shows a suspension insulator'constructed in accordance with my invention, the view being partly in section and partly in side elevation.

Suspension insulators fall into three general classes, first, those in which a dielectric is provided with interlocking passages known generally as the Hewlett type; second, those in which the connecting metallic members are rigidly connected within recesses in the body of the dieleectric material known as the J effrey DeWitt type, and third, the cap and pin type similar in principle to the insulator illustrated in the accompanying drawing.

Insulators of the first two classes or types, owing to the mass of material at the center of the dielectric, are limited in size and capacity by limitations of manufacture. Insulators of the cap and pin type, while not so limited, are nevertheless at the present time limited by a more serious consideration, namely, their mechanical strength. Various attempts have been made to overcome this defeet by increasing the mechanical strength of the cap and pin type insulators, and various expedients have been employed. The result of these expedients has been to materially increase the mechanical strength of these insulators to a point far beyond the point all been increased. It has been mainly due to the inability of the insulator manufacturers to produce suspension insulators of the necessary capacity and mechanical strength that the power companies have been prevented from employing voltages exceeding the present high voltage.

The object of the invention, as stated above, is to increase the mechanical strength of a suspension insulator, and since the mechanical strength is an important factor in the electrical strength of the insulator, it follows that an increase in mechanical strength will result in an increase in electrical strength.

I have found that the mechanical bond between the bolt and the dielectric formed by neat Portland cement is much stronger than the strength of the insulator. In other words, after the failure of the insulator by the rup ture of the dielectric in a test machine, it requires a force nearly one hundred per cent larger to shear the cement bond by which the bolt is connected to the interior recess of the dielectric than it did to rupture the dielectric of the assembled insulator. Ihave also found by careful test and by utilizing micrometer gauges that in the ordinary insulator there is an increase in diameter of the neck or stem at substantially per cent of the maximum load of quite an appreciable amount. I have therefore devised an insulator in which the parts are so arranged and constructed that the stresses transmitted from the cap to the dielectric are substantially equal to or slightly in excess of the stresses transmitted to the dielectric by the bolt, and in this manner prevent the expansion of the neck or stem of the insulator and hence materially increase the electrical and mechanical strength.

In carrying out my invention I provide a dielectric body portion 1 substantially ldentical with the dielectric shown in the joint copending application of Gouverneur and Stevens, Serial No. 748,222, filed November 6, 1924. The main difference between the dielectric 1 of the present application and the dielectric shown in the copending application is that the neck or stem 2 thereof is of increased length so that the bolt receiving recess 3 is somewhat deeper than in the copending ease. Combined with the dielectric 1 is a cap 4 which, while illustrated as of the clevls type, may of course be provided with any suitable attaching means, the said cap having an interior recess 5 conforming substantially to the contour of the neck or stem 2 of the dielectric. Adjacent its lower edge the ca is provided with a plurality of steps forxne by the conoidal surfaces 6, 7 and 8, the said conoidal surfaces being disposed at an acute angle to a line tangent to the surface of the neck or stem 2. Each adjacent pair of conoidal surfaces is connected by other conoidal surfaces the planes of which are disposed at right angles to the planes of the conoidal surfaces 6, 7 and 8. Preferably the lower extremity of the cap 5 on the exterior face thereof is reinforced so as to rovide a rigid substantially non-yielding ring or band 9.

Within the recess 3 there is provided a two step bolt 10 the steps preferably comprising conoidal surfaces 11 and 12 the angularity of said surfaces being substantially equal, the base of the surface 11 being'connected to the flaring portion of the surface 12 by a conoidal surface 13, as clearly shown in the drawing.

It will be seen from the cross sectional portion of the figure that the angularity of the surfaces 11 and 12, that is, the included angle between a line tangent to either surface 11 and 12 and the vertical, is substantially three times as greatas the included angle formed by a line tangent to the conoidal surfaces 6, 7 and 8 with the vertical. This ratio between the angularity of the steps of the bolt and the steps of the cap is provided so as to equalize the pressure transmitted from bolt and cap, respectively, to the dielectric. It will be obvious that the area of the dielectric adjacent the bolt is approximately one third only of the dielectric adj acentthe cap, and it is therefore essential, if the stresses transmitted respectively from bolt and cap are to be equalized, to provide an arrangement such as described above between the angularity of the surfaces of the steps of the cap and bolt so that the stresses for a unit area will be equalized.

In order to provide the necessary relative movement between the cap andthe ad 'acent cement and between the bolt and its ad acent cement, I preferably coat the interior surface of the cap and the exterior surface of the bolt, prior to the assembly, with what is known in the trade as cut sarco, that is, refined asphalt dissolved in a suitable solvent such as gasoline or the like. This cut sarco provides in effect a lubricatin compound which permits the necessary refittive movement between the cap and the exterior face of the cement and be tween the bolt and its cement, so that these lines of force to which reference has heretofore been made will be so transmitted to the body of the insulator as to in effect floatingly support the portion of the dielectric which is interposed between the cap and the pin. It will be noted also that the lowermost step on the pin is positioned by reason of the extension of the recess 5 at a point so spaced from the edge of the cap that any line normal to the conoidal surface 12 will lie above the lower edge of the cap.

Insulators constructed in accordance with the invention herein described, without any other or further change in either the character of the material or the amount of cement, show a test value in excess of one hundred per cent larger than the corresponding insulators not so constructed.

Having thus described the invention, I

claim V 1. In an insulator, a dielectric body and outer and inner metallic members secured thereto and each having a plurality of steps including conoidal surfaces, the angle of the conoidal surfaces of the outer member with respect to the vertical being substantially less. than the angle of the conoidal surfaces of the inner member with respect to the vertical.

2. In an insulator, a dielectric body and outer and inner metallic members secured thereto and each havin a plurality of steps including conoidal sur aces, the angle of the conoidal surfaces of the outer member with respect to the vertical being substantially less than the angle of the conoidal surfaces of the inner member with respect to the vertical, the conoidal surfaces of the outer member being out of horizontal alinement with those of the inner member.

3. In an insulator, a dielectric body and outer and inner metallic members secured thereto and each having a plurality of steps including conoidal surfaces, the angle of the conoidal surfaces of the outer member with respect to the vertical being. substantially less than the angle of the conoidal surfaces of the inner member with respect to the vertical, the conoidal surfaces of the outer member being out of horizontal alinement with those of the inner member and the location of the lowermost conoidal surface of the inner member being such that any line normal thereto will lie above the lower edge Of the outer member.

4. In an insulator, a body of dielectric material formed with an upstanding stem and further formed with a recess in its underside, connected by other conoidal surfaces normal a metallic cap secured upon the stem and a thereto, the angle of the first named conoidal metallic pin secured within the recess, the surfaces of the pin being a multiple of the ancap having its lower portion formed with gle of the first named conoidal surfaces of successive steps including conoidal surfaces the cap when considered with respect to the connected by other conoidal surfaces normal vertical.

thereto, and the pin being formed with a plu- In testimony whereof I aifix m signature. rality of steps including conoidal surfaces MINOR F. H. GOUVE NEUR.

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