The invention relates to polymer composition comprising a polyolefin (a) and an inorganic filler (b) wherein the polyolefin (a) is obtainable by a high pressure process which process comprises the steps: (i) compressing one or more monomer(s) under pressure in a compressor, using a compressor lubricant for lubrication, (ii) polymerising a monomer optionally together with one or more comonomer(s) in a polymerisation zone, (iii) separating the obtained polyolefin (a) from the unreacted products and recovering the separated polyolefin (a) in a recovery zone, wherein in step (i) the compressor lubricant comprises a non-mineral oil, power cable, for example a direct current (DC) power cable, use of a polymer composition and a process for producing a DC power cable.