Publication: Electrical Age
New York, NY, United States
Improved Strain Insulators
IN the manufacture of strain insulators, some important features that are necessary, if the insulators are to be used on pressures higher than 500 volts, are sometimes overlooked. A good strain insulator should have sufficient insulated distance between the two metal parts, sufficient surface insulation, obtained by long distance from metal part on one end to metal part on the other end, and sufficient strength and uniformity in the metal parts.
In the annexed illustration is shown an improved strain insulator, manufactured by the Creaghead Engineering Company, of Cincinnati, Ohio, designed to embody the features just mentioned.
The metal parts are two steel links, generally similar to chain links, made of material of high tensile strength. These links are separated and insulated from each other by a hard porcelain separator, giving considerable distance between the metal parts, and a high electrical resistance.
Around the metal parts and porcelain spreader, is moulded, under very great pressure an insulating compound that thoroughly seats the metal parts on the porcelain, filling all spaces between the porcelain and links, thoroughly weatherproofing the porcelain spreader and protecting it against mechanical injury. This insulating compound is not intended to give the insulator any material mechanical strength, but to protect the spreader. It materially increases the