High voltage dual dielectric capacitor roll

Claim 1

A round roll capacitor having a rating from about 250 volts AC to about 440 volts AC comprising: (a) a casing, (b) a capacitor roll in said casing comprising an elongated sheet of plastic film having a first layer of metallization on a first side thereof, said first layer extending substantially to a first longitudinal edge of said sheet and being spaced from a second longitudinal edge of said sheet, said sheet of film having a second layer of metallization on the second side thereof, said second layer extending substantially to said second longitudinal edge of said sheet and being spaced from said first longitudinal edge; (c) one or more sheets of metallization free paper substantially adjacent to said film; (d) a round core in said roll on which said sheets of film and paper are tightly rolled to form a capacitor roll wherein the film and the paper are in the dielectric field; (e) an impregnant having a dielectric constant above about 3 in said roll; and (f) said impregnated roll having essentially a zero space factor after impregnation and the design voltage stress on said paper is above about 500 volts per mil thickness and above about 1000 volts per mil thickness on said film.