Frangible casing for filter in high tension appts. - bursts under vacuum applied before filling with insulating gas

摘要

High tension appts. which in use is filled with insulating gas contains a filter for adsorbing moisture present in the gas. The filter when first installed has an air-tight casing which bursts open when the appts. is evacuated prior to filling with the inert gas. The casing may be a metal or plastic foil, and this may constitute a frangible closure for a portion of the high tension appts. The closure may include a gas-permeable ceramic disc The absorptive capacity of the filter is not reduced by premature exposure to the moisture-contg. air present before the preliminary evacuation takes place, and the filter may therefore remain effective for many years.