Publication: The Telegraphic Journal and Electrical Review
OPPENHEIMER'S LIGHTNING GUARD INSULATOR.
THIS invention is designed to obviate the inconvenience which arises in working telegraph lines from the breakage of insulators by lightning, and a consequent making of earth contact by the conducting wires. In order to avoid this kind of fault, a lightning discharger is introduced in the interior of the insulator, which is provided with a metallic covering.
The accompanying fig. shows a section of the improved insulator.
At a is the metallic insulator pin connected with the post, supported in this case to be of metal, and having formed or attached thereon a screw b which supports the earthenware or other such insulator c, open at the top, as shown in the fig. On the out side of this insulator is a metallic cap d, secured by means of cement e, and to this metallic cap the telegraph line wire is attached in the ordinary manner.
Upon the top a* of the insulator pin is placed a ring fof insulating material, and the distance to which this ring extends determines the distance between the top of d* of the cap and an extended part g of the pin a. This distance may be varied to some extend, but that shown in the fig., which is 1/4 scale, may be taken as the relative standard.
By this arrangement an effective lightning discharger is obtained within the insulator, the lightning passing through the top d* of the cap to the post g, and from thence along the pin a to earth.
In cases where wooden posts are used, the pin a may be connected to earth by means of an earth wire in the usual manner.