Publication: Electrical Review
New York, NY, United States
Insulators for Extremely High-Voltage Lines.
The accompanying illustrations show some new developments in insulators for high-voltage lines which have been brought out by Fred M. Locke. The frame-type insulator shown in Fig. 1 has been designed for lines requiring 150,000 volts line pressure. This insulator will stand a spray test of 280,000 volts, leaving a large factor of safety. It will carry a mechanical load of 20,000 pounds, and can be constructed to carry as much more as desired by increasing the I-beams and side rods and the bearing surface of the porcelain. The frames are interlocked like a chain, and the line can 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 unsual static stresses, and is extremely quiet up to the arcing point which takes place between the frames. In case of an arc from lightning, this 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 volts, with a factor of safety of two under a spray test and any mechanical load desired. The insulator is designed for the hanging type but can be supported at either end, and may be used horizontally or perpendicularly. The insulator is manufactured exclusively by the Lima Insulator Company, Lima, N. Y., under Mr. Locke's rights to patent which are now pending.
Fig. 2 illustrates Mr. Locke's 450,000-volt 150-kilowatt transformer, which is used to test these insulators. This is installed at the Lima Insulator Company's plant, and was made by the Central Laboratory Supply Company, of Lafayette, Ind.
Fig. 3 shows the porcelain bushings manufactured by the Lima Insulator Company for the 450,000-volt, 150-kilowatt transformer. These are insulating successfully the lead wires. The bushings are oil-filled, and the holes through the top caps support the choke-coils at each terminal. These bushings weigh about 200 pounds each.