Abstract :
The manufacture of apparatus for pressures of 88,000 volts or more resolves itself into the proper selection and arrangement of insulating materials. Of all the problems involved in this selection and arrangement, that of insulating the terminal wires where they pass through the case presents the greatest difficulty. When the terminal wires are carried through a metal cover the danger from breakdown is increased, yet the tendency of the latest designs is toward the use of metal tanks and covers. Even with present voltages the greatest difficulty lies in bringing out the terminal wires through the case. What may be termed “brute force” has characterized the proportioning of high-tension terminals up to the present time, as almost every class of insulating material in nearly every possible shape has been used to surround the conductor as it passes through the top of the case. The top itself has often been made of insulating material such as wood, simply to assist in insulating the lead.
