Publication: The Journal of Electricity, Power and Gas
San Francisco, CA, United States
INSULATORS FOR EXTREMELY HIGH VOLTAGE LINES.
The frame type insulator shown in Figure 1 was designed for lines requiring 150,000 volts, line pressure. It is stated that it will stand a spray test of 280,000 volts, leaving a large factor of safety, and carry a mechanical load of 20,000 pounds. It can be constructed to carry as much more as desired by increasing the eye beams and side rods and the bearing surface of the porcelain. The frames are interlocked like a chain so that the line will not come down. All the porcelain parts are under compression and are designed to have a surface large enough to carry the required mechanical load with a large factor of safety. Under an electrical test this insulator does not show the usual static stresses and is extremely quiet up to the arcing point which takes place between the frames. In case of an arc from lightning, it will take place between the frames and not injure the insulator. These insulators are furnished in any size for line voltages from 70,000 volts up to 300,000 with a factor of safety of 2 under a spray test, and any mechanical load desired. It is designed for the hanging type, but can be supported at either end and can be used horizontally or perpendicularly. It is manufactured by the Lima Insulator Company, Lima, N. Y., as designed by Mr. F. M. Locke, whose patents are now pending.
Figure 2 illustrates a 450,000-volt, 150-kilowatt transformer used to test the above insulator, and is installed at the Lima Insulator Company's plant. It was made by the Central Laboratory Supply Company, Lafayette, Ind. Figure 3 shows porcelain bushings manufactured by the Lima Insulator Company for Locke 450,000-volt, 150-kilowatt transformer and is insulating successfully the lead wires. These bushings are oil-filled and the holes through the top caps are to support the coke coils at each terminal. They weigh about 200 pounds each.