Conventional clip-in fuse holders for cylindrical cartridge fuses exhibit certain deficiencies with respect to high voltage insulation protection. Such holders typically consist of a pair of spring clips mounted on a base and configured to engage the end terminals of a cylindrical cartridge fuse by pressing insertion. The clips, together with unitary or separate terminal lugs, are normally secured to the base by a metallic rivet, screw or bolt and nut passing through a hole in the clip base and through a matching hole passing through the mounting base. Since these fasteners are in electrical contact with the clips, a short circuit can occur through the clips and fasteners if the bottom faces of the fasteners are exposed below the mounting base to contact any conducting surface on which the fuse holder may be mounted.
One solution involves provision of a separate insulating spacer inserted between the fuse mount base and the supporting surface. This solution is undesirable, since it requires an extra part, raises the overall height of the fuse structure and, thus, wastes space and poses tailoring problems for multiple fuse mount arrays of differing numbers of fuses.
An alternative solution is to provide a relatively thick fuse mounting base and to counterbore the rivet hole at the lower face of the mounting base to place the lower end of the rivet higher in the structure. This solution has the drawback that the surface walls of the counterbore walls serve as surface flashover paths at high voltages unless the base thickness is appropriately increased, again resulting in increased overall height of the fuse mount. Additionally, the rivets are extra parts in the assembly, and thus add materially to the manufacturing inventory. Accordingly, it is an object of the invention to provide an inexpensive, easily assembled fuse mount with less parts and without conducting passages through the base so as to achieve a reduced structure height for a given voltage rating.
It is frequently observed that low-priced snap-in cartridge fuses have their end terminals oriented significantly off-axis. Such structures are typically rather fragile, owing to the customary method of end terminal attachment, and as a result the terminals frequently break off when such fuses are inserted into conventional fuse holders with rigidly coaxially aligned fuse clips. Accordingly, it is an object of this invention to provide for self-aligning clips as a feature of the fuse mount to accommodate off-axis end terminals without such breakage.