Microprocessor controlled fault indicator having led fault indication circuit with battery conservation mode

• US 6,734,662 B1
• Filed: 10/25/2002
• Issued: 05/11/2004
• Est. Priority Date: 10/26/2001
• Status: Active Grant

• Current Assignee: Schweitzer Engineering Laboratories, Incorporated
• Original Assignee: E.O. Schweitzer Manufacturing Compay, LLC
• Inventors: Fenske, Kurt James
• Primary Examiner(s): Nguyen, Vinh P
• Application Number:
  US10/280,219
• Time in Patent Office: 564 Days
• Field of Search: 324/126, 324/127, 324/133, 324/512, 324/522, 340/660, 340/661, 340/662, 340/663, 340/664
• US Class Current: 324/127
• CPC Class Codes: G01R 15/148 involving the measuring of a magnetic field or electric field G01R15/18, G01R15/20, G01R15/24, G01R15/26 take precedence
• CPC Class Codes: G01R 19/16571 comparing AC or DC current with one threshold, e.g. load current, over-current, surge current or fault current G01R19/16514, G01R19/16519, G01R19/16528, G01R19/16533, G01R19/1659 take precedence; measuring currents by using elements sensitive to the magnetic field generated G01R15/14; measuring earth resistance G01R27/18; testing for leakage or short circuits in electrical apparatus G01R31/52
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: G01R 31/58 Testing of lines, cables or conductors testing of electric windings G01R31/72
• CPC Class Codes: H02H 3/042 combined with means for locating the fault locating faults in cables G01R31/08

Abstract

A fault indicator for indicating the occurrence of a fault in an electrical conductor has a housing, a high capacity battery, at least one light emitting diode (LED) visible from the exterior of the fault indicator upon the occurrence of a fault, and electronic circuitry for sensing a fault, for actuating the LEDs to indicate a fault and to provide a timed reset of the LEDs to a non-fault indicating condition a predetermined time after the fault has occurred. The electronic circuitry, including a microprocessor that is normally in a sleep mode, conserves energy by drawing insubstantial current from a high capacity battery during non-fault conditions. During fault conditions, a light sensor senses the ambient lighting conditions and the microprocessor reduces current supplied to the LEDs under reduced lighting levels, such as night, further conserving battery life. The LEDs may also be operated at an intermediate illumination level, such as at dusk or dawn.

Claims

1. A fault indicator for indicating the occurrence of a fault in an electrical conductor, comprising:

a housing;

a battery;

a fault sensor for sensing the occurrence of a fault on said electrical conductor;

at least one light emitting diode operable from said battery and viewable from the exterior of the housing;

a light sensor for sensing the ambient light level, and

a microprocessor in communication with said fault sensor to determine when a fault has occurred on said electrical conductor, in communication with said light sensor to determine the ambient light level, to enable the supply of power from said battery to said at least one light emitting diode upon determining that a fault has occurred, to cease enabling power from said battery to said at least one light emitting diode at a predetermined time after determining that a fault occurred and to reset said fault indicator around said predetermined time;

said microprocessor responding to a lower ambient light level by reducing the power supplied to said at least one light emitting diode during lower ambient light levels, thereby conserving battery power.

2. The fault indicator as defined in claim 1 wherein said at least one light emitting diode comprises two light emitting diodes.

3. The fault indicator as defined in claim 1 wherein said microprocessor enables power from said battery to be provided to said at least one light emitting diode by means of pulse width modulation signals to further conserve battery power.

4. The fault indicator as defined in claim 3 wherein said pulse width modulation signals comprise a series of pulses which enable power to be provided from said battery to said at least one light emitting diode, followed by a longer off time in which power is disabled from being provided to said at least one light emitting diode.

5. The fault indicator as defined in claim 4 wherein the series of pulses in said pulse width modulation signals number in the range of three to five pulses.

6. The fault indicator as defined in claim 4 wherein the series of pulses in said pulse width modulation signals enable power to be provided to said at least one light emitting diode for about one second followed by an off time in which no further series of pulses occur for a few to several seconds.

7. The fault indicator as defined in claim 1 wherein said microprocessor is normally in a sleep mode, said microprocessor is awakened upon said fault sensor sensing a fault, and said microprocessor returns to the sleep mode after resetting the fault indicator.

8. The fault indicator as defined in claim 1 wherein said microprocessor determines an intermediate ambient light level between the ambient light level normally encountered during the daytime and the lower light level normally encountered during the nighttime, said microprocessor responsive to the intermediate ambient light level to control the amount of power supplied to said at least one light emitting diode to an intermediate level.

9. The fault indicator as defined in claim 1 wherein said predetermined time after determining that a fault has occurred is in the range of 1 to 24 hours.

10. A fault indicator for indicating the occurrence of a fault in an electrical conductor, comprising:

a housing;

a battery;

a fault sensor for sensing the occurrence of a fault on said electrical conductor;

at least one indicator capable of being illuminated by power from said battery and viewable from the exterior of the housing;

a light sensor for sensing the ambient light level; and

a microprocessor in communication with said fault sensor to determine when a fault has occurred on said electrical conductor, in communication with said light sensor to determine the ambient light level, to enable power from said battery to said at least one indicator upon determining that a fault has occurred, to cease enabling power from said battery to said at least one indicator at a predetermined time after determining that a fault occurred and to reset said fault indicator around the predetermined time after determining that a fault occurred;

said microprocessor responding a lower ambient light level by reducing the power supplied to said at least one indicator during lower ambient light levels, thereby conserving battery power.

11. The fault indicator as defined in claim 10 wherein said microprocessor enables power from said battery to be provided to said at least one indicator by means of pulse width modulation signals to further conserve battery power.

12. The fault indicator as defined in claim 11 wherein said pulse width modulation signals comprise a series of pulses which enable power to be provided from said battery to said at least one indicator, followed by a longer off time in which power is disabled from being provided to said at least one indicator.

13. The fault indicator as defined in claim 12 wherein the series of pulses in said pulse width modulation signals number in the range of three to five pulses.

14. The fault indicator as defined in claim 12 wherein the series of pulses in said pulse width modulation signals enable power to be provided to said at least one indicator for about one second followed by an off time in which no further series of pulses occur for about 2 to 10 seconds.

15. The fault indicator as defined in claim 10 wherein said microprocessor is normally in a sleep mode, said microprocessor is awakened upon said fault sensor sensing a fault, and said microprocessor returns to the sleep mode after resetting the fault indicator.

16. The fault indicator as defined in claim 10 wherein said microprocessor determines an intermediate ambient light level between the ambient light level normally encountered during the daytime and the lower light level normally encountered during the nighttime, said microprocessor responsive to the intermediate ambient light level to control the amount of power supplied to said at least one indicator to an intermediate level.

17. The fault indicator as defined in claim 10 wherein said predetermined time after determining that a fault has occurred is in the range of 1 to 24 hours.