Diagnostic blown fuse indicator

• US 6,859,131 B2
• Filed: 05/25/2001
• Issued: 02/22/2005
• Est. Priority Date: 05/25/2001
• Status: Active Grant

• Current Assignee: Littlefuse Incorporated
• Original Assignee: Littlefuse Incorporated
• Inventors: Kennedy, John, Stanek, Dan, Klinger, Lawrence Mark
• Primary Examiner(s): Vortman, Anatoly
• Application Number:
  US09/864,972
• Publication Number:
  US 20020175800A1
• Time in Patent Office: 1,369 Days
• Field of Search: 337/206, 337/241, 337/242, 337/245, 337/265, 337/266, 439/490, 439/491, 439/622, 324/507, 324/550, 324/691, 340/638, 340/639, 361/835, 81/38, 116/202
• US Class Current: 337/206
• CPC Class Codes: H01H 85/30 Means for indicating condition of fuse structurally associated with the fuse
• CPC Class Codes: H01H 85/32 Indicating lamp structurally associated with the protective device

Abstract

The present invention provides a blown fuse indicator. More specifically, the present invention provides a blown fuse indicator adapted for use with multiple element fuses, which provides a perceivable distinction between a blown fuse due to a current overload and a blown fuse due to a short circuit. To this end, in one embodiment of the present invention, a diagnostic blown fuse indicator is provided for a fuse having both a short circuit element and a current overload element. The indicator includes a short circuit indicator in electrical communication with the short circuit element, wherein the short circuit indicator provides visual indication of a short circuit condition. The indicator also includes a current overload indicator in electrical communication with the current overload element, wherein the current overload indicator provides visual indication of an overload condition.

Claims

1. A fuse having both a short circuit element and a current overload element, comprising:

a short circuit indicator electrically communicating in parallel with the short circuit element, wherein the short circuit indicator is coated with a chemical composition that is adapted to vaporize after a short circuit occurs;

a current overload indicator electrically communicating in parallel with the current overload element, wherein the overload indicator is coated with a chemical composition that is adapted to vaporize after a current overload occurs; and

a single, rigid body that houses the short circuit element, current overload element, short circuit indicator and current overload indicator, wherein, (i) the body is fixed to conductive end caps that are exposed and configured to be fitted to mating connectors, (ii) the elements and indicators communicate electrically with the end caps, and (iii) the body defines at least one opening sized and shaped for a person to view both indicators located within.

2. The fuse of claim 1, which includes a viewing area that changes visually when the short circuit element opens and when the current overload element opens.

3. The fuse of claim 1, which includes a first viewing area that changes visually when the short circuit element opens and a second viewing area that changes visually when the current overload element opens.

4. The fuse of claim 1, wherein the current overload element is electrically communicating in series with the short circuit element.

5. A fuse having diagnostic blown fuse indication comprising:

a short circuit element having an area of higher electrical resistance between conductive ends, the area tending to open upon a short circuit;

a time delay element communicating electrically with one of the ends of the short circuit fuse element, the time delay element opening due to a current overload;

a short circuit indicator operating in parallel with the short circuit element;

a current overload indicator operating in parallel with the time delay element; and

a single, rigid body that houses the short circuit element, time delay element, short circuit indicator and current overload indicator, wherein, (i) the body is fixed to conductive end caps that are exposed and configured to be fitted to mating connectors, (ii) the elements and indicators communicate electrically with the end caps, and (iii) the body defines at least one opening sized and shaped for a person to view both indicators located within.

6. The fuse of claim 5, wherein the short circuit indicator is electrically communicating in parallel with the short circuit element.

7. The fuse of claim 5, wherein the current overload indicator is electrically communicating in parallel with the time delay element.

8. The fuse of claim 5, wherein the time delay element is electrically communicating in series with the short circuit element.

9. The fuse of claim 5, at least one of the indicators includes gun cotton and an igniter wire in contact with the gun cotton.

10. The fuse of claim 5, wherein at least one of the indicators is coated with a chemical composition that vaporizes upon a fault condition.