Fuse state indicator

An electric fuse comprising:

• a tubular fuse body having a first end, a second end, and an aperture for fuse state identification;
• first and second end caps coupled to said body;
• a primary fuse element electrically connected between said first and second end caps;
• and
• a fuse indicator assembly comprising a secondary fuse link electrically connected between said first and second end caps, a readily ignitable and combustible substance adjacent said secondary fuse link, and a flexible backing layer coupled to an extension member and maintaining said secondary fuse link in position with respect to said combustible substance, said flexible backing layer assuming a curvature complementary to a curvature of the tubular fuse body.

An electric fuse comprising:

• a tubular fuse body having a first end and a second end and an aperture for fuse state identification;
• first and second end caps coupled to said body;
• a primary fuse element electrically connected between said first and second end caps;
• and
• a fuse indicator assembly comprising:
• an extension member having an outer surface, the outer surface having curvature complementary to an outer surface of the tubular body;
• a secondary fuse link electrically connected between said first and second end caps;
• a readily ignitable and combustible substance adjacent said secondary fuse link;
• and
• a flexible backing layer coupled to said extension member and adjacent said secondary fuse link, said flexible backing layer assuming the curvature of the extension member when secured thereto and maintaining said secondary fuse link in position proximate said combustible substance for visible fuse state indication through said aperture of said fuse body by the presence or absence of said combustible substance, wherein said combustible substance is substantially completely combusted after said primary fuse element has opened.

A fuse state indicator for a fuse including a primary fuse element in an insulative body, the insulative body having an aperture therethrough for fuse state identification, said fuse state indicator comprising:

• an insulative extension member having a body defining a substantially cylindrical outer surface and defining a cavity extending from the cylindrical outer surface;
• an ignitable and combustible substance received within said cavity;
• a secondary fuse link extending across said extension member and said cavity such that said secondary fuse link is positioned adjacent said combustible substance;
• and
• a backing layer coupled to said extension member and closing said cavity over said combustible substance, wherein said secondary fuse link is positioned between said backing layer and said combustible substance, said backing layer being flexed to conform to the cylindrical shape of the extension member and at least partially concealed by said combustible substance when viewed through the aperture in insulative fuse body before the primary fuse element has opened, said backing layer maintaining said secondary fuse link in position with respect to said combustible substance, said combustible substance being ignited and combusted to reveal said backing layer when said secondary fuse link opens.