The present invention is a structure comprising a biaxially oriented film having a layer comprising a homopolymer of propylene which layer is in contact with oil, characterised in that the homopolymer of propylene has a content of isotactic pentads of from 95% to 98% and a content of ash of not more than 30 ppm.

A method and apparatus for storing energy. An apparatus comprises a first plate, a second plate, and a spacer. The spacer comprises a material having a plurality of pores, being open pores. The spacer is located between the first plate and the second plate. The apparatus further includes an enclosure, the first plate, the second plate, and the spacer located within the enclosure, the enclosure defining a volume, wherein the enclosure further defines a wall, and further comprising a second spacer disposed between the wall and one of the first plate and the second plate.

A method and apparatus for storing energy. An apparatus comprises a first plate, a second plate, and a spacer. The spacer comprises a material having a plurality of pores, being open pores. The spacer is located between the first plate and the second plate. The apparatus further includes an enclosure, the first plate, the second plate, and the spacer located within the enclosure, the enclosure defining a volume, wherein the enclosure further defines a wall, and further comprising a second spacer disposed between the wall and one of the first plate and the second plate.

The present invention provides a capacitor oil that can maintain breakdown voltage at a high level in a wide temperature range of 50 C. to 30 C., extremely unlikely precipitates as crystals in particular at 50 C. and thus has excellent properties both at normal temperature and a lower temperature. The capacitor oil of the present invention comprises 1,1-diphenylethane and benzyltoluene, wherein the mass ratio of 1,1-diphenylethane to benzyltoluene is 0.8 to 2.0, the total amount of the ortho-isomer and para-isomer in the benzyltoluene is 90 percent by mass or less, and the composition has a 40 C. kinematic viscosity of 3.00 mm.sup.2/s or lower.

Methods and systems are provided for impregnating capacitors and other receptacles with a fluid. In one example, a system may include a reservoir of a purified fluid to be used to impregnate one or more receptacles and a manifold configured to withstand an internal pressure differential to cause the purified fluid to infiltrate the manifold. The system may further include a convection oven in which the one or more receptacles and the manifold are located when the one or more receptacles are impregnated with the purified fluid.