US2297430A - Antenna insulator - Google Patents

Description

Sept. 29, 1942. w PETERS 2,297,430

ANTENNA INSULATOR Filed Sept. 30, 1939 INVENTOR. W/L HELM PETERS ATTORNEY.

Patented Sept. 29, 1942 ANTENNA INSULATOB Wilhelm Peters, Berlin, Germany; vested in the Alien Property Custodian Application September 80, 1939, Serial No. 297,295 In Germany September 8|, 1988 6 Claims.

This invention relates to a new and novel insulator for supporting cables for antennas.

The high masts for transmitter antennas are anchored by means of steel cables. In order to prevent them from absorbing energy from the antenna they have to be divided into sections which are not in harmonic relation to the transmitted frequency by means of steel cable insulators In the case of high transmitter powers, the antenna will be surrounded by strong electrical fields so that these insulators are exposed to considerable voltage loads. In addition to the resistance to mechanical tensions which become very high, especially for instance, in case of rain,- these insulators should also fulfill the following conditions: The insulator should be subjected primarily to compression stresses since the compression strength ofthe ceramic'insulating material is much higher than the tension strength. In the event that an insulator breaks, the antenna mast is to be made safe against toppling over. The cable must not break. The insulator should have as low a capacity as will be possible thereby separating favorably the individual cable parts from one another. The first two conditions were sought to be complied with by means of socalled egg insulators known in the prior art.

However, considerable difficulties are encountered in attempting to develop this form of insulator for high voltages. The disadvantage of these insulators resides in that the field lines traverse in certain numbers the air, as well as the inulating material, so that an overcharging of the air gap and therewith a corona discharge can easily set in. In order to avoid such a possibility, very large dimensions must be used. Therefore, the insulators become heavy and thick so that they cause an unnecessary stress in the cable parts. For this reason, so-called cable hooks have been developed, which can withstand a particularly high tension stress so that they avoid corona discharges in the form above mentioned, but these hooks have the disadvantage that in order to obtain a unilateral compression stress, an insulator pair is to be employed whereby the bearing links are subjected to unfavorable bending stresses. Therefore, these traverses must have rather large dimensions. Owing to these traverses, and the double arrangement of the insulatcrs, the structure is extremely heavy. Also, the mounting of this suspension arrangement causes great difllculties.

In accordance with the present invention, there is employed an insulator which will be subjected that, on the one hand, the field lines pass respectively only in the air or only in the insulator, and on the other hand, the link which is designed as a hook and transmits the pressure to the insulator undergoes substantially tension stresses. This invention will be more clearly understood by referring to the accompanying drawing, in which Fig. 1 shows an example of construction for this novel insulator. Fig. 2 shows an insulator constructed similar to Fig. 1, except that it is adapted to receive a cable; and Fig. 3 shows a suspension method of two U-shaped half hooks.

Referring now in detail to the drawing, it will be noted that in Fig. 1, the edges on which a high field intensity could appear are completely avoided. For the sake of propriety, the tension resistance of the break down air gap between the armatures of the hook and designated by (1-0 will be chosen just as high or somewhat lower than the tension resistance of the creep distance I 11-27 along the insulator and the point of metal to compression stresses and which is so shaped and insulation contact will be at a different level for adjacent members to thus further reduce the solid dielectric within the electric field. In this case, the discharge at overvoltages takes place along the distance aF-a, so that the insulator proper will not be affected by the arc. According to Fig. 1, the link-like armature parts I and 2 and the metallized bearing surfaces 4 of the insulator 3 are uniformly ground or turned which assures a favorable transmission of the pressure. However, it is also possible to place the cable part around the insulator just as in the case of an ordinary cable. such as shown by way of example, in Fig. 2. The cable 2' rests hereby in a semitoroid-like depression or turned groove 4' which is metallized to prevent corona discharges. Fig. 3 shows the application'of the invention to a suspension consisting of two half links 5, 5' which can be screwed together for example, by a right and left hand thread. These chain links are joined by the two nuts t, 6' while the ties are joined with the cables at I.

What is claimed is:

1. An electrical cable insulator comprising a solid approximately semi-cylindrical insulator having two flattened paths the lengths of which are less than a semi-circle, said paths being located at intersecting planes and extending in-opposite directions on the outer surface thereof, a pair of metallic members contacting the surfaces of said paths so that the electrical field lines pass either through the air only or through the insulator.

2. An electrical cable insulator comprising a solid approximately semi-cylindrical insulator having two flattened paths the lengths of which are less than a semi-circle, said paths being located at intersecting planes and extending in opposite directions on the outer surface thereof, a metallized coating covering the surfaces of both of said paths.

3. An electrical cable insulator comprising a solid approximately semi-cylindrical insulator having two flattened paths the peripheryoi said paths being less than their diameter, said paths being located at intersecting planes and extending in opposite directions on the outer surfaces thereof, a central portion of said paths being concaved to receive a rod-like member, and a pair of metallic link members contacting the concaved surfaces of said paths.

4. An electrical cable insulator comprising a solid approximately semi-cylindrical insulator having two flattened paths the periphery of said paths being less than one-half their diameter, said paths being located at intersecting planes and extending in opposite directions on the outer surface thereof, a metallized coating covering the surface oi said flattened paths, and a pair of rodaeamso 5. An electrical cable insulator comprising a solid approximately semi-cylindrical insulator having two flattened paths the periphery of said paths being less than one-half their diameter, said paths being located at intersecting planes and extending in opposite directions on the outer surface thereof, a central portion of said paths being concaved to receive a rod-like member, a metallized coating covering said concaved surfaces, a pair of metallic iinlr members contacting the surfaces of said concaved paths.

6. An electrical cable insulator comprising a pair of solid approximately semi-cylindrical insulators each having two flattened paths the periphery of said paths being less than one-half their diameter, said paths being located at intersecting planes and extending in opposite directions on the outer surface thereof, a pair of metallic half-link members contacting the surfaces of said paths of each insulator, and a pair of coupling members for joining each of said halilinl: members together.

WILHEIM PETERS.

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