Diagnostic fuse indicator including visual status identifier

• US 7,636,028 B2
• Filed: 07/20/2006
• Issued: 12/22/2009
• Est. Priority Date: 07/20/2005
• Status: Active Grant

• Current Assignee: Littelfuse Incorporated
• Original Assignee: Littelfuse Incorporated
• Inventors: Whitney, Stephen J., Rodseth, William G.
• Primary Examiner(s): Vortman; Anatoly
• Application Number:
  US11/458,922
• Publication Number:
  US 20070018775A1
• Time in Patent Office: 1,251 Days
• Field of Search: 337/206, 337/297, 337/241, 337/243, 337/265, 324/550
• US Class Current: 337/243
• CPC Class Codes: H01H 85/30 Means for indicating condition of fuse structurally associated with the fuse

Abstract

Electrical fuse indicators which may be used to diagnose and identify a fault state or failure mode of the electrical fuse include in various exemplary embodiments, indicator materials such as a reactive material, which are incorporated into various fuse indicator devices to cooperate with a visually perceptible indicator portion or layer to indicate the failure mode or fault state if the electrical fuse.

Claims

1. A diagnostic fuse indication device, the device comprising:

a short circuit element;

a short circuit indicator electrically coupled to the short circuit element in a parallel arrangement, wherein the parallel arrangement comprises a shunt;

an overload current element electrically coupled to the short circuit element in a series arrangement, and electrically coupled to the short circuit indicator in a series arrangement;

an overload current indicator electrically coupled to the overload current element in a parallel arrangement, wherein the parallel arrangement comprises a shunt, the overload current indicator also electrically coupled to the short circuit element in a series arrangement;

a first indicator material deposited adjacent to the short circuit indicator; and

a second indicator material deposited adjacent to the overload current indicator, wherein the first indicator material reacts in response to a short circuit event to reveal the short circuit indicator, and wherein the second indicator material reacts in response to an overload current event to reveal the overload current indicator, wherein the first and second indicator materials each comprise at least one spark gap.

2. The fuse indication device of claim 1, wherein the short circuit element is a conductive metal comprising a plurality of bridges.

3. The fuse indication device of claim 1, wherein the overload current element is manufactured from the material selected from the group consisting of copper-nickel alloy, silver plated brass, tin lead solder, lead free solder, copper, gold, silver, zinc or their alloys having a suitably low melting temperature.

4. The fuse indication device of claim 1, wherein the first and second indicator materials are reactive materials.

5. The fuse indication device of claim 4, wherein the reactive materials are nano-layered films.

6. The fuse indication device of claim 4, wherein the reactive material is configured to produce a self-propagating exothermic reaction in response to an energy input.

7. The fuse indication device of claim 6, wherein the energy input is selected from the group consisting of:

a current overload, a short circuit, a heated filament, a flame, focused radio frequency radiation, or light amplification by stimulated emission of radiation.

8. The fuse indication device of claim 4, wherein the reactive material is deposited to form at least one high resistance bridge.

9. The fuse indication device of claim 8, further comprising a first offset resistor electrically coupled to the short circuit indicator in a series arrangement, and a second offset resistor electrically coupled to the overload current indicator in a series arrangement.

10. The fuse indication device of claim 4, wherein the at least one spark gap comprises a gap of about 0.002 inches (about 50 micrometers).

11. The fuse indication device of claim 1, further comprising at least one housing that supports the short circuit element and the short circuit indicator.

12. A diagnostic fuse indication device, the device comprising:

a short circuit element;

a short circuit indicator electrically coupled in a parallel arrangement to the short circuit element, wherein the parallel arrangement comprises a shunt;

an overload current element electrically coupled to the short circuit element in a series arrangement;

an overload current indicator electrically coupled to the overload current element in a parallel arrangement, wherein the parallel arrangement comprises a shunt;

a first reactive material deposited adjacent to the short circuit indicator; and

a second reactive material deposited adjacent to the overload current indicator, wherein the first and second reactive materials each comprise at least one spark gap, and

wherein the first reactive material reacts in response to a short circuit event to reveal the short circuit indicator, and wherein the second reactive material reacts in response to an overload current event to reveal the overload current indicator.

13. The fuse indication device of claim 12, wherein the reactive material is configured to produce a self-propagating exothermic reaction.

14. The fuse indication device of claim 12, wherein the reactive material is a nano-layered film.

15. The fuse indication device of claim 12, wherein the reactive material is an indicator material consisting of high-carbon content silver.

16. A diagnostic fuse indication device, the device comprising:

an insulating substrate;

a short circuit indicator assembly carried by the insulating substrate, the short circuit indicator including;

a short circuit element;

a short circuit indicator electrically coupled in a parallel arrangement to the short circuit element, the parallel arrangement comprising a shunt;

a reactive material deposited adjacent to the short circuit indicator, wherein the reactive material reacts in response to a short circuit event to reveal the short circuit indicator; and

a current overload assembly carried by the insulating substrate and electrically coupled to the short circuit assembly, the current overload assembly including;

an overload current element;

an overload current indicator electrically coupled in a parallel arrangement to the overload current element, wherein the parallel arrangement comprises a shunt;

a reactive material deposited adjacent to the overload current indicator, wherein the reactive material reacts in response to an overload current event to reveal the overload current indicator, wherein the reactive material deposited adjacent to the short circuit indicator and the reactive material deposited adjacent to the overload current indicator each comprise at least one spark gap separating portions of the reactive material.

17. The fuse indication device of claim 16, wherein insulating substrate is manufactured from the material selected from the group consisting of:

flame retardant woven glass reinforced epoxy laminates, non-woven glass laminates, ceramics, PTFE, microfiber glass substrates, thermoset plastics, polyimide materials, or any combination of these materials.

18. The fuse indication device of claim 16, wherein the reactive material is configured to produce a self-propagating exothermic reaction.

19. The fuse indication device of claim 16, wherein the reactive material is a nano-layered film.

20. The fuse indication device of claim 16, wherein the reactive material is an indicator material consisting of high-carbon content silver.