Glass Insulators for High Voltages; Swiss Insulators

Glass Insulators for High Voltages

Tests with glass insulators have been in progress in Switzerland for several years, and numbers of these insulators have been used in France and the United States for potentials up to 50,000 volts. The principal application for glass insulators is, however, up to 25,000 volts. Such failures as have occurred with glass insulators have been due principally to internal stresses which cause cracking when the insulator is subjected to heavy mechanical stress or sudden change of temperature. The occurrence of such failure has been made less frequent by the use of improved material and better annealing. As for the puncture strength, it is higher than that of glazed, hard porcelain. The glass used in Switzerland is clear and transparent, hence the absorption of solar heat is less than in the dark green glass hitherto employed. - Pottery Gazette and Glass Trade Review.