US 4,870,387 A · Beam strengthened cutout insulator

Abstract

An improved, integrally cast, synthetic resin insulator (22) especially adapted for use in an electrical cutout device (20) is provided which can be readily fabricated and gives greatly enhanced beam strength and arc track resistance characteristics. The preferred insulator (22) is cast using an epoxy resin such as bisphenol A filled with a relatively large quantity of glass beads and hydrated alumina. The filler fraction contributes to lowered viscosity, deaerability and improved settling properties while the resin is in an uncured state, and moreover enhances the arc track resistance and mechanical strength of the resin system after curing. The preferred insulator (22) is cast to present a longitudinal bow giving the insulator (22) an arcuate central axis. Further, the periphery of the insulator (22) is formed with a series of superposed, generally oval-shaped in cross-section, outwardly flaring skirts (30) interconnected by smooth transition regions (32) free of stress-inducing sharp corners. By virtue of the oval-shaped skirts (32), the insulator (22) has a greater effective width than thickness, thus maximizing the beam strength of the insulator (22).

Claims9

Dependent claims

An electrical cutout device comprising:

an elongated, integrally cast insulator body formed of synthetic resin material and having superposed, outwardly flared skirts about the periphery thereof over a substantial portion of the length of the body with a pair of generally opposed, endmost faces respectively defining the butt ends of the body,
said insulator body being longitudinally bowed and presenting an arcuate central axis between said endmost faces;
respective elongated electrical terminals secured to said insulator body at end regions proximal to said endmost faces and including line-connecting structure for electrical connection of the device within an electrical circuit, each of said terminals extending laterally from a corresponding end region with the longitudinal axis thereof transverse to said central axis,
each of said endmost faces lying in a plane which is generally parallel with the longitudinal axis of the corresponding adjacent terminal;
elongated fuse means adapted to sever upon experiencing a fault current;
and
means including an elongated fuse tube receiving said fuse means located in spanning relationship to said terminals for mounting said fuse means and electrically coupling the same with said terminals to complete an electrical circuit therebetween.

4 more elements

Dependencies are inferred from the claim text.

Beam strengthened cutout insulator

Life of this patent

Beam strengthened cutout insulator

Life of this patent

Abstract

Claims9