Abstract An oil impregnated electrical conduit comprises a conductive metal, a cellulosic insulator, and a hydrorefined insulation oil, wherein the hydrorefined oil has a viscosity in the range of 10012,000 SUS at 100* F., contains 10-65 weight percent aromatics (by gel analysis) and less than 10 p.p.m. of basic nitrogen (preferably less than 5 p.p.m. and typically less than 2 p.p.m.). Typically, such an oil can contain more than 10 p.p.m. of total nitrogen (e.g., 15-600 p.p.m.) depending on the viscosity of the oil. Preferably, the hydrorefined oil is naphthenic or aromatic (by VGC classification). A preferred conduit is an oil-filled electrical cable wherein the cellulosic insulator is paper and is wrapped around the conductive metal. A preferred paper is capacitor grade Kraft paper of relatively high density and can be creped or microcreped. The cellulosic insulator can also comprise chemically treated cellulose such as cyanoethylated cellulose or acetylated cellulose.
An electric cable according to claim 1 wherein said cellulosic insulator is a paper and is wrapped around said conductive metal.
Claim 2
Dependent Claim
38 words
An oil-filled electrical cable according to claim 2 wherein said paper is a pure wood pulp Kraft paper with no sizing, coloring, or chemical additives and wherein said hydrorefined oil contains less than 5 p.p.m. of basic nitrogen.
Claim 3
Dependent Claim
21 words
An oil-filled electrical cable according to claim 2 wherein said paper is capacitor grade Kraft paper of a relatively high density.
Claim 4
Dependent Claim
21 words
An oil-filled electrical cable according to claim 4 and wherein said hydrorefined oil contains less than 5 p.p.m. of basic nitrogen.
Claim 5
Dependent Claim
21 words
An oil-filled electrical cable according to claim 5 and wherein said hydrorefined oil contains less than 2 p.p.m. of basic nitrogen.
Claim 6
Dependent Claim
17 words
An oil-filled electrical cable according to claim 1 and wherein said cellulosic insulator is a Kraft tissue.
Claim 7
Dependent Claim
17 words
An oil-filled electrical cable according to claim 1 and wherein said cellulosic insulator is creped or microcreped.
Claim 8
Dependent Claim
17 words
An oil-filled electrical cable according to claim 1 and wherein said cellulosic insulator is creped or microcreped.
Claim 9
Dependent Claim
16 words
An oil-filled electrical cable according to claim 1 and wherein said cellulosic insulator comprises cyanoethylated cellulose.
Claim 10
Dependent Claim
15 words
An oil-filled electrical cable according to claim 10 wherein said cellulosic insulator comprises acetylated cellulose.
Claim 11
Dependent Claim
42 words
An oil-filled electrical cable according to claim 1 and wherein said cellulosic insulator has been thermally upgraded by the incorporation of a nitrogen-containing compound, said nitrogen-containing compound being chemically bonded to the cellulose and serving to to protect the fibers against degradation.