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Method of detecting faults in the insulation layer of an insulated concealed conductor

  • US 5,828,219 A
  • Filed: 08/12/1997
  • Issued: 10/27/1998
  • Est. Priority Date: 08/22/1996
  • Status: Expired due to Term
First Claim
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1. A method of detecting faults in the insulation layer of an insulated concealed conductor, comprising the steps of:

  • (i) applying a first alternating current with a frequency of less than 10 Hz to the insulated concealed conductor;

    (ii) detecting the field generated at a selected point along the concealed conductor with a magnetometer, the magnetometer being part of a detector;

    (iii) applying a second alternating current with a frequency of more than 10 Hz to the insulated concealed conductor;

    (iv) detecting the field generated by the second alternating current at said selected point along the concealed conductor with a magnetic field detector, said magnetic field detector being a further part of said detector;

    (v) determining the depth of the concealed conductor at said selected point using said detected field generated by the second alternating current;

    (vi) deriving the magnitude of the first alternating current at said selected point;

    (vii) repeating steps (i) to (vi) for a plurality of selected points, the detector being moved between the plurality of selected points; and

    (viii) determining the variation of said first alternating current between said plurality of selected points, thereby to detect changes in the gradient of said variation of current, thereby to detect faults in the insulation layer.

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