Combined pupin coil and insulator for telephone lines in Germany

Combined Pupin Coil and Insulator

Pupin load coils are coming into use in Europe for telephone lines of considerable length, especially in Germany, where there appears to be the greatest progress in this direction. Such coils are placed upon the pole lines and are spaced the proper distance apart. But as some good means must be provided for protecting the coils against the weather, some of the constructors have been looking for the most practical method of carrying this out. A good solution seems to be that shown in the accompanying sketch. What is novel in this case is the combination of the porcelain insulator of the line with the coil itself, so as to contain the later within the insulator. The drawing shows how this is carried out so as to lodge both the Pupin coil and the resistance for the lightning arrester, the latter being placed on the pole.

Combined Pupin Coil and Insulator.

An insulator is used of the single-petticoat form, and it is made with an annular chamber near the upper part. Coil and resistance are placed together and form a ring which fits into the chamber of the insulator, leaving a small clearance. Once in place a screw cap working upon the core of the insulator closes up the chamber at the bottom. Melted insulating matter is then run in around the coil through a hole in the cap, so as to hold it solidly in place and prevent any moisture from reaching the coil through the joints of the cap. By this method of construction, the main body of the insulator remains in a single piece, and it is as strong and as easily made as an ordinary insulator.