Oil immersible current limiting fuse assembly

Abstract

A current limiting fuse especially adapted for installation within the oil tank of a transformer for protecting the latter from the effects of high magnitude fault currents is provided which is completely fluid-submersible and capable of withstanding severe thermal cycling without damage to the fluid-tight seals thereof. In addition, the fuses hereof are especially constructed for permitting quick, individual helium testing thereof in order to ensure that the fuses meet required safety standards. The main body of the fuse is encapsulated within a fluid-impervious casing of filled epoxy material which is penetrated by a pair of opposed, end-mounted, electrically conductive terminals each being threadably connected to the body of the fuse and bearing against a respective resilient seal member to form fluid-tight seals between the opposed terminals and the apertured ends of the encapsulating casing. In this manner leakage of oil or other contaminants between the fuse body and encapsulating material is effectively prevented during substantially all conditions encountered in practice. The seals between the casing and the terminals are preferably supplemented by a rigid, non-porous potting compound emplaced around the terminals over the respective seal areas in order to render the entire fuse assembly essentially tamperproof.