Provided is an impregnated capacitor wherein at least part of the capacitor element comprises a metallized polypropylene base film impregnated with an insulating impregnating agent comprising a compound having three condensed or non-condensed aromatic rings, the ratio of the amount of the impregnating agent which penetrates between the base film layers to that of said agent which penetrates into the base film per unit thickness ( mu ) being at least 60.
