Hemingray Glass Company

"Provo" Insulator.

The Hemingray Glass company of Covington, Ky., is placing on the market the "Provo" type insulator for high-potential work, which has given such excellent results on the 40,000-volt plant of the Telluride Power Transmission company in Utah. The insulator was perfected nearly a year and a half ago, and is the outcome of several years of experiment, with existing types and many new forms.

"Provo" Insulator.

It is all glass, which is the cheapest insulating material and, according to the makers, is the only one that is absolutely reliable when exposed to the weather and the action of high-potential currents.

It is 5 3/4 inches high and seven inches in diameter and has five petticoats. Two of these petticoats are near the line wire and serve to break the continuity of the exposed surface between the wire and the pin of the cross-arm, which tends to prevent jumping of the current between these points. Another advantage of these petticoats near the line wire is that they protect surfaces of small area and high resistance, which check surface breakage at its source. It is noticed in actual practice that these surfaces remain free from moisture and snow. The other petticoats on the bottom extend the surface distance from the line wire to the pin to 16 inches.

The line wire is tied around the insulator in the topmost groove, which holds it well above the cross-arm. This method of tying has been adopted, as it is considered the best for use in a country where the strain on an insulator may be either up or down or sidewise.

The thickness of glass is well proportioned and the insulator is extra strong in resisting mechanical breakage or electrical punctures. Tests have been made between the points for the wire and the pin with voltages as high as 125,000, without puncturing the material. The thread is of standard size and 2 1/2 inches long. The strain of the wire comes squarely on the pin. The glass is almost colorless and the insulator is not conspicuous on a pole line.

The name of Hemingray is a sufficient guarantee for good work in the glass-insulator line. The company has increased facilities for manufacturing this insulator and is prepared to fill orders on short notice.