Partially impregnated capacitor

Claim 1

A capacitor having a voltage rating in the range of from above about 350 volts AC to 750 volts AC comprising in combination a. a capacitor roll section having a dielectric and electrode system which consists solely of synthetic resin strips some of which have metal film coatings thereon as the sole electrode structure, b. said dielectric strips being of less than 0.5 mils thickness to bear a voltage stress of from above about 1200 to 1750 volts per mil at the rated voltage of the capacitor, c. said strips being wound under heavy tension on a hard cylindrical core to provide a hard round capacitor roll section highly resistant to dielectric liquid penetration at the roll edges, d. a sealed casing containing said roll section, e. and a non halogenated dielectric liquid filling said can and submerging said roll edges, and f. said roll section having a substantially dry central section which predominates the distance between the roll edges which is not penetrated by the dielectric liquid, and narrow margin sections at said edges which are wet by the dielectric liquid.