Method for diagnosing degradation in aircraft wiring

• US 6,909,977 B2
• Filed: 12/08/2000
• Issued: 06/21/2005
• Est. Priority Date: 12/08/1999
• Status: Expired due to Term

• Current Assignee: Harry E. Orton
• Original Assignee: Harry E. Orton
• Inventors: Orton, Harry E.
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Charioui, Mohamed
• Application Number:
  US10/149,530
• Publication Number:
  US 20030105598A1
• Time in Patent Office: 1,656 Days
• Field of Search: 702/65, 702/66, 702/69, 702/75, 702/76, 702118-121, 702183-185, 702/189, 702/58, 702/64, 385/12, 324/96, 324/501, 324/522, 324/529, 324/544, 324/536, 340/3.42, 340/500, 398/6
• US Class Current: 702/65
• CPC Class Codes: G01R 31/008 on air- or spacecraft, railway rolling stock or sea-going vessels
• CPC Class Codes: G01R 31/088 Aspects of digital computing
• CPC Class Codes: G01R 31/1218 using optical methods; using charged particle, e.g. electron, beams or X-rays
• CPC Class Codes: G01R 31/1272 of cable, line or wire insulation, e.g. using partial discharge measurements locating faults in cables G01R31/083
• CPC Class Codes: G01R 31/58 Testing of lines, cables or conductors testing of electric windings G01R31/72
• CPC Class Codes: H02H 1/0023 sensing non electrical parameters, e.g. by optical, pneumatic, thermal or sonic sensors

Abstract

Wiring in new and older aircraft use bundled insulated conductors that are subject to deterioration overtime that can result in on-board fires, loss of in-flight control and eventual crashes of the aircraft. The present invention provides a diagnostic method which permits the on-line and non-destructive diagnosis of the insulation degradation in a portion of the wiring comprising: a) measuring the current flow at locations of the aircraft wiring utilizing an optical current sensor with a bandwidth of dc to 50 kHz; b) determining the current flow within a high frequency bandwidth; and c) analyzing the results of the current flow differential determination and initiate the following: i) detect and locate the point of cable failure; ii) initiate an alarm annunciation; and iii) initiate an on-board sectionalized fire suppression system.

Claims

1. A method of on-line diagnosis of insulation degradation in a portion of low voltage wiring cable in aircraft and other vehicles having a central processing unit comprising the steps of:

i) measuring the current flow at two locations on said low voltage cable utilizing an optical current sensor with a bandwidth of dc to 50 kHz;

ii) communicating said measurements to said central processing unit;

iii) said central processing unit determining the current flow difference between said two locations at one or more frequencies in the range 10 kHz to 50 kHz;

iv) said central processing unit analysing the results of the current flow difference determination using at least one diagnostic measurement technique to locate a potential cable wiring fault.

2. The method of claim 1 wherein said current flow has a frequency of 400 Hz.

3. The method of claim 2 wherein said at least one diagnostic measurement technique comprises determining the harmonic component of the 400 Hz insulation leakage current to establish the degree of insulation deterioration that has occurred.

4. The method of claim 2 wherein said at least one diagnostic measurement technique comprises using the output of one of said optical current sensors at one of said locations to measure the harmonic component of the 400 Hz insulation leakage current to establish the degree of insulation deterioration that has occurred.

5. The method of claim 2 wherein the voltage of said current flow is less than 1000 volts.

6. The method of claim 1 wherein said current flow measurement is carried out at multiple sectionalized locations in said aircraft or other vehicle.

7. The method of claim 1 further comprising the step of annunciating an alarm in said central processing unit if a potential cable wiring fault is located.

8. The method of claim 1 further comprising the step of said central processing unit initiating an on-board fire suppression system if a potential cable wiring fault is located.

9. The method of claim 1 wherein said at least one diagnostic measurement technique comprises a time domain reflectometry technique.

10. The method of claim 1 wherein steps i), ii) and iii) are performed a plurality of times over a period of time and the resultant plurality of current flow differences are averaged for purposes of the analysis in step iv).

11. An aircraft or other vehicle having an insulated low voltage electrical cable, comprising optical current sensors with a bandwidth of dc to 50 kHz mounted at two spaced locations on said low voltage cable for measuring the current flow at said two spaced locations on said cable, and central processing means connected to said optical current sensors comprising computer readable program code means for determining the current flow difference at one or more frequencies in the range 10 kHz to 50 kHz and analysing the results of the current flow difference to locate a potential cable wiring fault using at least one diagnostic measurement technique.

12. The aircraft or other vehicle of claim 11 wherein said current flow has a frequency of 400 Hz.

13. The aircraft or other vehicle of claim 12 wherein said at least one diagnostic measurement technique comprises further determining the harmonic component of the 400 Hz insulation leakage current to establish the degree of insulation deterioration that has occurred by using the output of one of said optical current sensors at one of said locations to measure the harmonic component of the 400 Hz insulation leakage current.

14. The aircraft or other vehicle of claim 12 wherein the voltage of said current flow is less than 1000 volts.

15. The aircraft or other vehicle of claim 11 wherein said central processing means is adapted to make a plurality of said measurements of current flow over a period of time to provide a plurality of current flow differences and average said plurality of current flow differences for purposes of analysing the results of the current flow difference to locate a potential cable wiring fault.

16. The aircraft or other vehicle of claim 11 wherein said at least one diagnostic measurement technique comprises a time domain reflectometry technique.