Abstract: Power capacitors with a wide electrode and a narrow electrode and a composite dielectric including a first portion adjacent the narrower electrode that is of higher dielectric constant and/or lower resistivity than the portion adjacent the wider electrode. The first portion may be a porous material whose impregnation with a suitably chosen dielectric fluid results in the desired electrical properties. In such structures the narrower electrode preferably has rounded and smooth edges such as by folding. The wide and narrow electrodes may each comprise one of the externally connected capacitor electrodes. Alternatively, the wider electrode may be electrically floating and arranged between dielectrics and a second narrower electrode in a symmetrical arrangement with the two narrower electrodes serving as the externally connected capacitor electrodes.

Abstract: A capacitor is disclosed of layers of metal foil alternating with insulating sheets impregnated with a dielectric fluid. The dielectric fluid comprises a mixture of 80 to 99% by weight mono-ethylated, mono-propylated, or mono-butylated biphenyl, biphenyl oxide, or biphenyl methane and about 1 to about 20% by weight di-ethylated, di-propylated, or di-butylated biphenyl, biphenyl oxide, or biphenyl methane.