US2270964A - Insulator for antenna span or guy ropes - Google Patents

Description

Jan. 27, 1942. w, PETERS 2,270,964

INSULATOR FOR ANTENNA SPAN 0R GUY ROPES Filed March 12, 1940 2 Sheets-Sheet 1 ATTORNEY.

W/LHELMPETERS INVENTOR.

, Jan. 27, 1942.

Filed March 12, 1940 W. PETERS INSULATOR FOR ANTENNA SPAN 0R GUY ROPES 2 Sheets-Sheet 2 INVENTOR. W/LHELM PETERS Patented Jan. 27, 1942 Y U NlTED STATES PATENT-OFFICE I K 2,270,964 I 1 i INSULATOR FOE ANTENNA SPAN OR GUY ROPES graphic m. b. E, Berlin tion of Germany Germany, a corpora- Application March 12, 1940, Serial No. 323,531 In Germany December 29, 1938 Claims.

This invention is concerned with an insulator for antenna strain or guy ropes or cables of the kind disclosed, 'in'my copending application Se rial No. 297,295, filed September 30, 1939.

The parent patent (application) disclosed a span rope or guy wire insulator which possesses very favorable properties in electrical respect,

(high fiashover potential) and in mechanical re gard (high tensile strength). The design thereof is so chosen that according to-practial requirements, either the electric or the mechanical load carrying capacity is high, or else both these properties are combined. The longer the working wave of a station, the higher as a. general rule must be the self-oscillating antenna tower "or mast, and the greater, also, the tensile stress site flashover or breakdown potential of the guy wire insulator chain. This flashover potential is a function of the flashover strength or potential of the individual insulator units, as well as of the number of insulators linked together. The number thereof is further governed by the subdivision of the guy cable, this being necessary to preclude the changes of electric swaying of the cable.

Now, the high mechanical loads here involved makes it imperative to polishand grind the insulator bearing surfaces and areas with a view to insuring uniform load transmission. For this reason, the principal contour lines of the insulator must lie in a. boundary of two cylinders crossing at rightangles, as illustrated by the accompanying drawings, in which:

Fig. 1a is a side elevation of an insulator of this invention; Y

Fig. lb is another side elevation taken at right angles from that of Fig. la;

Fig. 2 is a side elevation of another embodimentof this invention, including belts; L

Fig. 3 is a side elevation of still another embodiment of this invention, including a broad bearing surface;

Fig. 4 is a side elevation of afurther embodi ment oi this invention, including a form which is flattened at the bottom end;

Fig. .5 is an elevation of a composite insulator with a metal end;

Fig. '8 is a section of an insulator formed with a central cavity and an annular member; I

Fig. 9a is a side elevation of an insulator with a fluted leakage path; n Fig. 9b is another side elevation of an insulator taken at ninety degrees from that of Fig.

According to the invention, for a given mechanical load .carrying area, maximum breakdown or flashover, strength is insured by fitting the contour or profile of the insulator exactly in these envelopes of cylindrical form. Figs. 1a and 1b show an exemplified embodiment. For a given diameter a of the insulator, the projection .of the bearing surface b.a is given by the mechanical load; hence, the bearing surface is proportional to the width. The higher the ratio b/a, the lower will be the electrical flashover potential of the insulator. The width b of the bearing surface has a minimum value for reasons of mechanical safety which is conditioned by the demand that the insulator unit should not tip or tilt out of the assembly.

Fig. 2 shows an embodiment of a belt insulator comprising belts or bands made of wire rope or cable being, if necessary, held together surface by means of a flattened,

in the bearing bush.

An embodiment as shown in Fig. 3 is preferable in cases where the mechanical load demands are severe, but electrical requirements moderate. In this form of construction, the bearing surface is broad, while the flashover distance is relatively reduced. The greater the mechanical load, the broader or wider of necessity the insulator, and the greater, also, the volume of ceramic material used for it and its weight. An increase in weight is undesirable from the mechanical viewpoint, for the reason that it will increasethe pull on the guy wires to an undue and unnecessary degree. Limitations upon the mass and volume of such a body are also imposed for manufacturing reasons, that is,--for reasons of baking and burning.

I, The following Figs. 4, 5 and 6 illustrate exemplified embodiments of the invention in which ceramic material has been saved. Fig. 4 shows a form which is flattened at the bottom end. In .the case of Fig. 5, metal is used in lieu of the ceramic material that hasbeen spared. In the embodiment Fig. 6 two semi-circular bodies being separately baked, are fitted on top of each other crosswise, tipping relative to each other being optionally prevented by a pin or peg imprisoned therein and consisting also of ceramic material. In the forms or; construction known in the earlier art, the transmission of pressure from the parallel belts to the insulator lies in a This means semi-circular cylindrical surface.

that in addition to compressive stress upon the ceramic material, there is set up also a certain amount of bending stress, that is, tensile stress in certain zones. As a consequence, a limitation is imposed upon the mechanical load carrying capacity of the insulator. According to the invention, bending stress in the body is diminished by mounting the belts so that there results a certain angle rather than parallelism. Embodiments of this object of the invention are illustrated by way of example in Figs. 7 and 8. As

shown in Fig. Lthe belts are spread apart by cross members '1 forming a compression rod. The result is that the cross-section 'of the iresulator has a segment less than semi-circular and that thus the bending stress set up therein is reduced, but at the same time the flashover po tential is raised. In order to reduce the length of the link assembly, recourse could be had to an and 9b, this is insured by corrugations or fluting o! the insulator surface or else by fins fitted upon the surface of the insulator.

What is claimed is:

1. A cable insulator comprising a dielectric body the principal contour lines of which lie in a boundary 0! two semi-cylindrical members crossed at right angles to each other, the hall circumference of one member ending at substantially the same plane where the half circumference of the other member begins.

2. A cable insulator comprising a dielectric body the principal contour lines of which lie in a boundary of two semi-cylindrical members crossed at right angles to each other, the half circumference of one member ending at substantially the same plane where the half circumference of the other member begins, and a web portion connecting each side of each member and extending to meet the portion of an opposed member where its halt circumference ends on said body.

3. A cable insulator comprising a dielectric body the principal contour lines or which lie in a boundary of two semi-cylindrical members crossed at right angles to each other, the half circumference of one member ending at substantially the same plane where the hall circumierence of the other member begins, and the face of each member being slightly concaved.

4. A cable insulator. comprising a dielectric body the principal contour lines oi which lie in a boundary of two semi-cylindrical members crossed at right angles to each other, the half circumference of one member ending at substantially the same plane where the half circumference of the other member begins, a web portion connecting each side of each member and extending to meet the portion of an opposed memher where its half circumference ends on said body, and a plurality of corrugations. on the surface of said web portions to increase the leakage

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