Gas insulated electric apparatus

A gas insulated electric apparatus comprising an insulating tube and an electric high voltage appliance arranged inside the insulating tube, whereby

• the insulating tube comprises a permeation barrier arranged on an inside wall of the insulating tube,
• the insulating tube contains an insulation gas comprising at least 70% by volume of CO2 and/or N2 and comprising an elevated and pre-determined operating gas pressure level,
• the permeation barrier comprises a protective layer and a permeation layer,
• the protective layer is provided as solvent based epoxy layer facing the insulation gas,
• the permeation layer is radially arranged between the insulating tube and the protective layer, and
• the permeation layer comprises polyvinyl alcohol, ethylene vinyl alcohol, and/or polyurethane.

A method for manufacturing a gas insulated electric apparatus comprising an electric high voltage appliance for being arranged inside an insulating tube, comprising:

• manufacturing the insulating tube,
• applying, during manufacturing, a permeation barrier onto an inside wall of the insulating tube, and
• filling the insulating tube with an insulation gas comprising at least 70% by volume of CO2 and/or N2 and comprising an elevated and pre-determined operating gas pressure level, whereby
• the permeation barrier comprises a protective layer and a permeation layer,
• the protective layer is provided as solvent based epoxy layer facing the insulation gas,
• the permeation layer is radially arranged between the insulating tube and the protective layer, and
• the permeation layer comprises polyvinyl alcohol, ethylene vinyl alcohol and/or polyurethane.