Patent ID: 7658808

Claim:
A method for enhancing the dielectric properties of at least one electrical cable section having a central stranded conductor encased in a polymeric insulation jacket and having an interstitial void volume in the region of the conductor, the cable section having an average operating temperature T, the method comprising: (a) filling the interstitial void volume with at least one dielectric property-enhancing fluid composition at a pressure below the elastic limit of the polymeric insulation jacket; and (b) confining the dielectric property-enhancing fluid composition within the interstitial void volume at a residual pressure greater than about 50 psig, the pressure being imposed along the entire length of the section and being below the elastic limit, wherein the composition comprises at least one component selected from: (1) a water-reactive material selected from (i) an organosilane monomer having at least two water-reactive groups, (ii) the above organosilane monomer (i) wherein at least one of the water-reactive groups has been substituted with a condensable silanol group, (iii) an oligomer of the above organosilane monomer (i), or (iv) a co-oligomer of the above organosilane monomer (i), the organosilane monomer (i) having a diffusion coefficient at least about 15 times greater than the diffusion coefficient of its corresponding tetramer, the diffusion coefficient being determined at temperature T; (2) a water-reactive material selected from (i) an organosilane monomer having at least two water-reactive groups, (ii) the above organosilane monomer (i) wherein at least one of the water-reactive groups has been substituted with a condensable silanol group, (iii) an oligomer of the above organosilane monomer (i), or (iv) a co-oligomer of the above organosilane monomer (i), the water-reactive material (2) having at least one group attached to silicon comprising 7 to about 20 —CH 2 — units; (3) a non-water-reactive organic material which has a diffusion coefficient of less than about 10 −9 cm 2 /sec and an equilibrium concentration of at least about 0.005 gm/cm 3 in the polymeric insulation, the diffusion coefficient and the equilibrium concentration being determined at temperature T; or (4) an organic compound having an equilibrium concentration in the polymeric insulation at 55° C. which is less than 2.25 times the equilibrium concentration at 22° C.