Abstract: An electric fuse includes a cylindrical insulating housing with conductive terminal caps at opposing ends of the housing. Conductive ferrules are adjacent the terminal caps and electrically connected thereto. At least one main fusible element is disposed between the terminal caps and electrically connects the terminal caps. The ferrules are of a cylindrical configuration such that the fuse is operational through clip mounting of the ferrules. Bolt receiving means is provided for bolt mounting the fuse between a pair of conductive mounting bus bars. The bolt receiving means comprises a plurality of internally threaded passageways for securely receiving a threaded bolt. Each of the passageways respectively extends generally longitudinally inwardly through each of the terminal caps. The presence of the bolt receiving means presents substantially no impediment to the clip mounting operation of the fuse.

Abstract: An electric fuse is of the type including indicating means for indicating if the main fusible element has melted. The indicating means includes a first and second auxiliary fusible element, each having a higher resistance than the main fusible element. When the fuse is fully assembled, and the main fusible element has melted, the path of current is through the first and second auxiliary fusible elements. The second auxiliary fusible element functions to restrain movement of an indicator button. When current flows through the auxiliary fusible elements, the second auxiliary fusible element is designed to melt first, thereby causing the indicator button to move. The operability of the first and second auxiliary fusible elements can be independently and non-destructively determined before and after assembly of the fuse. After fuse assembly, the fuse can be non-destructively disassembled so as to determine the operability of the first and second auxiliary elements.

Abstract: A current-limiting power fuse has an indicator mechanism which includes a conductive support cup mounted on one terminal cap and containing an indicator button disposed telescopingly in the cup with an outer hermetically closed end. A spring inside the button biases the outer end face away from the support cup. The outer end of the button is held in place by a fusible indicator wire.The button is a bellows with the inner end hermetically sealed to the bottom of the support cup to isolate the fusible indicator wire from ambient gas.