METHOD AND SYSTEM FOR MONITORING AN UNDERGROUND ELECTRIC CABLE

• US 20090167308A1
• Filed: 12/26/2007
• Published: 07/02/2009
• Est. Priority Date: 12/26/2006
• Status: Active Grant

• Current Assignee: ELTA Systems Limited (Government of Israel)
• Original Assignee: ELTA Systems Limited (Government of Israel)
• Inventors: LOMES, Alexander
• Granted Patent: US 8,510,047 B2
• Time in Patent Office: Days
• US Class Current: 324/326
• CPC Class Codes: G01V 3/081 the magnetic field is produced by the objects or geological structures characterised by the method of magnetic field measurement G01R33/00

Abstract

In a method and system for monitoring an underground cable in a site of interest, multiple samples of magnetic field data and corresponding location data are collected periodically over a sampling period of extended time. The magnetic field data samples and corresponding location data are processed to determine respective topologies of one or more current-carrying conductors in the site and for each of the conductors respective magnetic field data relating to each sampled point are integrated with respect to a predetermined parameter of the respective conductor so as compute an integrated contribution of each sampled span along the respective conductor. The data relating to different conductors in the site are output in a manner that allows determination of a conductor for which the parameter changes during the sampling period.

Claims

1. Method for monitoring an underground cable, the method including:

obtaining multiple samples of magnetic field data and corresponding location data collected periodically over a sampling period of extended time,

processing said magnetic field data samples and corresponding location data to determine respective topologies of one or more current-carrying conductors in said site;

integrating for each of said conductors respective magnetic field data relating to each sampled point with respect to a predetermined parameter of the respective conductor so as compute an integrated contribution of each sampled span along the respective conductor; and

outputting data relating to different conductors in said site in a manner that allows determination of a conductor for which said parameter changes during the sampling period.

2. The method according to claim 1, wherein obtaining multiple samples of magnetic field data and corresponding location data includes flying above said site and collecting multiple samplings throughout the sampling period.

3. The method according to claim 2, including using an unmanned aircraft vehicle (UAV) to collect said samples.

4. The method according to claim 1, wherein outputting data includes graphically formatting a respective topology of each conductor and indicating in association with each conductor whether said parameter changes during the sampling period.

5. The method according to claim 4, including graphically formatting a respective field map for each conductor so as to show the respective topology of each conductor and indicating in association with different conductors their respective fields measured at different sampling periods.

6. The method according to claim 5, including color-coding segments in said topology according to the magnetic field of a respective span of a respective conductor sampled at the respective sampling period whereby a conductor span for which said parameter is constant is represented as a multi-segment line of constant color and a conductor for which said parameter changes is represented as a multi-segment line whose segments are of different colors.

7. The method according to claim 1, wherein said predetermined parameter is a length of the cable.

8. The method according to claim 7, including estimating rate of growth or decrease of a conductor of varying length as a gradient of color changes with time along the respective line.

9. The method according to claim 1, wherein said predetermined parameter is connection or disconnection of the cable to a source of electrical power.

10. Cable detection apparatus including:

a topology determination unit responsive to multiple samples of magnetic field data and corresponding location data collected periodically over a sampling period of extended time by scanning a site, said topology determination unit being configured to process said magnetic field data samples to determine respective topologies of one or more current-carrying conductors in said site;

an integrator coupled to the topology determination unit and being configured to integrate for each of said conductors respective magnetic field data relating to each sampled point with respect to a predetermined parameter of the respective conductor so as to compute an integrated contribution of each sampled span along the respective conductor; and

an output device coupled to the integrator for outputting data relating to different conductors in said site in a manner that allows determination of a conductor for which said parameter changes during the sampling period.

11. The cable detection apparatus according to claim 10, wherein the output device is coupled to a graphic formatting unit for formatting a respective topology of each conductor and indicating in association with each conductor whether said parameter changes during the sampling period.

12. The cable detection apparatus according to claim 11, wherein the graphic formatting unit is adapted to format a respective field map for each conductor so as to show the respective topology of each conductor and indicating in association with different conductors their respective fields measured at different sampling periods.

13. The cable detection apparatus according to claim 12, wherein the graphic formatting unit is adapted to color-code segments in said topology according to the magnetic field of a respective span of a respective conductor sampled at the respective sampling period whereby a conductor span for which said parameter is constant is represented as a multi-segment line of constant color and a conductor for which said parameter changes is represented as a multi-segment line whose segments are of different colors.

14. The cable detection apparatus according to claim 10, wherein said predetermined parameter is a length of the cable.

15. A cable detection system, including:

a data collection unit for obtaining multiple samples of magnetic field data and corresponding location data periodically over a sampling period of extended time;

a topology determination unit responsive to the multiple samples of magnetic field data and corresponding location data collected periodically over a sampling period of extended time by scanning a site, said topology determination unit being configured to process said magnetic field data samples to determine respective topologies of one or more current-carrying conductors in said site;

an integrator coupled to the topology determination unit and being configured to integrate for each of said conductors respective magnetic field data relating to each sampled point with respect to a predetermined parameter of the respective conductor so as to compute an integrated contribution of each sampled span along the respective conductor; and

an output device coupled to the integrator for outputting data relating to different conductors in said site in a manner that allows determination of a conductor for which said parameter changes during the sampling period.

16. The cable detection system according to claim 15, wherein the data collection unit includes:

a magnetometer,

a relative GPS module for receiving respective first and second signals from first and second sets of satellites together with respective first and second signals received from said first and second sets of satellites by a static, geographically well-defined reference point and further for receiving position data of the reference point;

a communication unit coupled to the magnetometer and the relative GPS module for relaying magnetic field data and associated position data of a scanned area to a data processing unit.

17. The cable detection system according to claim 16, wherein the magnetometer includes:

an antenna assembly, and

a signal processing unit for processing respective signals received by the antenna assembly.

18. The cable detection system according to claim 15, wherein the data collection unit is disposed in an aerial reconnaissance unit and the data processing unit is disposed in a ground unit.

19. The cable detection system according to claim 15 to 18, wherein the antenna assembly includes a pair of loop antennae and disposed in mutual orthogonal spatial relationship in a horizontal plane.

20. The cable detection system according to claim 19, wherein each loop antenna is formed of a large number of turns of permalloy contained within a brass shielding tube so as to shield the antenna from the electrical field component.

21. The cable detection system according to claim 20, wherein a longitudinal slot is formed in the brass shielding tube to reduce magnetic eddy currents circulating in the brass tube.

22. The cable detection system according to claim 19, further including:

respective low noise amplifiers connected to antennae within the antennae assembly for buffering voltages induced in the antennae;

a pair of band-pass filters each connected to a respective output of the low noise amplifiers for removing unwanted DC components of the earth magnetic field and high frequency components of the signal; and

a pair of A/D converters each coupled to a respective output of the band-pass filters for digitizing their respective analog signals prior to digital signal processing.

23. The cable detection system according to claim 15, wherein the output device is coupled to a graphic formatting unit for formatting a respective topology of each conductor and indicating in association with each conductor whether said parameter changes during the sampling period.

24. The cable detection system according to claim 23, wherein the graphic formatting unit is adapted to format a respective field map for each conductor so as to show the respective topology of each conductor and indicating in association with different conductors their respective fields measured at different sampling periods.

25. The cable detection system according to claim 24, wherein the graphic formatting unit is adapted to color-code segments in said topology according to the magnetic field of a respective span of a respective conductor sampled at the respective sampling period whereby a conductor span for which said parameter is constant is represented as a multi-segment line of constant color and a conductor for which said parameter changes is represented as a multi-segment line whose segments are of different colors.

26. The cable detection system according to claim 15, wherein said predetermined parameter is a length of the cable.

27. Program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform a method for monitoring an underground cable, the method including:

obtaining multiple samples of magnetic field data and corresponding location data collected periodically over a sampling period of extended time,

processing said magnetic field data samples and corresponding location data to determine respective topologies of one or more current-carrying conductors in said site;

integrating for each of said conductors respective magnetic field data relating to each sampled point with respect to a predetermined parameter of the respective conductor so as compute an integrated contribution of each sampled span along the respective conductor; and

outputting data relating to different conductors in said site in a manner that allows determination of a conductor for which said parameter changes during the sampling period.