Abstract: A method and apparatus are provided for reducing the oxygen content drawn from the atmosphere that enters the insulating fluid-containing expansion vessel of high-voltage systems. The apparatus is provided with inner and outer tanks that include a liquid that provides a diffusion barrier for capturing oxygen from the atmosphere. The tanks are in communication with the atmosphere on one side of the barrier and in communication with the expansion vessel on the other side of the barrier. Further provided is a moisture-capturing dehumidifier upstream of the diffusion barrier to dry the gas passing into the expansion vessel. The apparatus limits degradation of the insulation system caused by moisture and oxygen, thereby increasing the life span of the high-voltage system.

Abstract: The invention relates to a method for reducing the air feed from the atmosphere into the expansion vessel of high-voltage systems filled with insulating fluid and also relates to a device for carrying out the method, the design of the device differing for new transformer installations form that of transformers with thermal aging already having set in. This enables the limiting of degradation of the insulation system by the accelerators of moisture and oxygen and enables the life span of the high-voltage system to be extended.