Abstract An electrical insulator of porous expanded plastics material such as polyurethane for use within metal-clad high-voltage switchgear and lines and which are evacuated prior to being filled with a high-grade compressed insulating gas such as SF6 having an insulating capacity greater than that of air. Approximately 100 percent of the pores of the expanded plastics material are open pores so as to prevent destruction of the pores during the evacuation phase and thereafter enable the pores to be filled with the insulating gas while in the normal operating condition of the electrical apparatus. If desired, the pores adjacent certain surface zones may be closed so as to reduce the risk of contamination and facilitate cleaning.
A high-voltage electrical member mounted within and spaced from a pressurized insulation gas-filled metallic casing by an expanded polyurethane insulating member having an approximately 100 percent open-pore structure, said insulating member forming a stable support for said electrical member both during evacuation of said casing for the removal of air and subsequent filling with the pressurized insulating gas.
Claim 2
Dependent Claim
58 words
A high-voltage electrical member mounted within and spaced from a pressurized insulation gas-filled metallic casing by an expanded polyurethane insulating member having an approximately 100 percent open-pore structure, said insulating member forming a stable support for said electrical member both during evacuation of said casing for the removal of air and subsequent filling with the pressurized insulating gas.
Claim 3
Dependent Claim
31 words
The invention as defined in claim 1 wherein certain surface portions of said insulating member are characterized by closed pores thus to reduce the risk of contamination and facilitate cleaning thereof.
Claim 4
Dependent Claim
102 words
The invention as defined in claim 1 wherein said insulating member has a disc-shaped annular configuration within which said electrical member in the form of a conductor is supported and spaced from said metallic casing which has a cylindrical configuration, the side surface portions of said insulator member being characterized by closed pores thus to reduce risk of contamination and facilitate cleaNing thereof whereas the pores at the outer and inner cylindrical surfaces in contact with the inner wall of said casing and said electrical conductor respectively are open thereby to permit entry of the pressurized insulating gas which fills said casing.