Method of prioritizing anomalies in a buried linear conductor

• US 7,881,890 B2
• Filed: 05/05/2009
• Issued: 02/01/2011
• Est. Priority Date: 05/06/2008
• Status: Active Grant

• Current Assignee: Pure Technologies Limited (Xylem, Inc.)
• Original Assignee: Spectrum External Line Inspection Technology Inc.
• Inventors: Ukiwe, Chijioke, McDonnell, Shamus, Westman, Mike
• Primary Examiner(s): TSAI, CAROL S W
• Application Number:
  US12/435,484
• Publication Number:
  US 20090281746A1
• Time in Patent Office: 637 Days
• Field of Search: 702/64, 702/150, 324/515, 324/71.1, 324/700, 324/539, 324/716, 324/718, 324/542, 324/543, 324/529, 324/327, 324/520, 324/521, 324/551, 324/528, 324/530, 324/326, 324/66, 324/67, 738/658, 738/09, 737/99
• US Class Current: 702/64
• CPC Class Codes: G01R 31/1272 of cable, line or wire insulation, e.g. using partial discharge measurements locating faults in cables G01R31/083

Abstract

A method of prioritizing anomalies in a linear conductor buried under a ground surface includes the steps of obtaining prioritization values for a plurality of anomalies along a linear conductor, and ranking the prioritization values according to magnitude. For each anomaly, a prioritization value is obtained by: locating an anomaly; for each anomaly, determining a current, a depth of cover, and a voltage gradient using spaced voltage probes; using the depth of cover and the voltage gradient, calculating an effective probe spacing of the first and second voltage probes relative to the anomaly on the conductor; and determining the prioritization value of the anomaly based on a linear relationship between the voltage gradient and the product of the current and the effective probe spacing.

Claims

1. A method of prioritizing anomalies in a linear conductor buried under a ground surface, comprising the steps of:

obtaining prioritization values for a plurality of anomalies along a linear conductor, wherein, for each anomaly, a prioritization value is obtained using a method comprising the steps of;

locating an anomaly;

determining a current along the linear conductor at the anomaly, a depth of cover of the linear conductor, and a voltage gradient, the voltage gradient being determined using a first voltage probe at a first position and a second voltage probe at a second position, the first and second voltage probes taking a voltage reading and being separated by a probe spacing;

using the depth of cover and the voltage gradient, calculating an effective probe spacing of the first and second voltage probes relative to the anomaly on the conductor; and

determining the prioritization value of the anomaly based on a linear relationship between the voltage gradient and the product of the current and the effective probe spacing; and

ranking the prioritization values according to magnitude.

2. The method of claim 1, wherein determining the current and the depth of cover comprises using a measurement device.

3. The method of claim 2, wherein the probe spacing is constant for each anomaly.

4. The method of claim 1, wherein the first position is at a point directly above an anomaly of the linear conductor being measured, and the second position is spaced from the first position in a direction parallel to or perpendicular to the linear conductor.

5. The method of claim 1, wherein each of the first position and the second position are offset from a point on the ground surface directly above an anomaly being measured, the first probe and the second probe being spaced from the anomaly along a line perpendicular to the linear conductor.