Crosslinkable polymer composition and cable with advantageous electrical properties

A crosslinked DC power cable which comprises a conductor which is surrounded by at least an inner semi conductive layer comprising a first semiconductive composition, an insulation layer consisting of a polymer composition that has been crosslinked, and an outer semiconductive layer comprising a second semiconductive composition, in that order,

• wherein the polymer composition of said insulation layer consists of, prior to crosslinking, a polyolefin, an antioxidant, a peroxide and a scorch retarder, wherein said peroxide is present in an amount of 10.0 to 28 mmol —O—O—/kg polymer composition, and
• wherein the polyolefin is, prior to crosslinking, an unsaturated LDPE copolymer of ethylene with 1,7-octadiene, and
• wherein the unsaturated LDPE copolymer contains vinyl groups and the total amount of vinyl groups present in the unsaturated LDPE is higher than 0.54/1000 carbon atoms and 0.82/1000 carbon atoms or less,
• wherein the polymer composition has an electrical conductivity of 45 fS/m or less, and
• wherein the peroxide is dicumylperoxide,
• wherein the antioxidant is 4,4′-thiobis(2-tertbutyl-5-methylphenol),
• wherein the scorch retarder is 2,4-diphenyl-4-methyl-1-pentene,
• wherein the amount of antioxidant is 0.08 wt %,
• wherein the amount of the scorch retarder is from 0.05 wt % to 0.18 wt % relative to the total amount of the polymer composition.