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Non-destructive status determination for electric power cables

  • US 5,101,161 A
  • Filed: 10/12/1990
  • Issued: 03/31/1992
  • Est. Priority Date: 10/12/1990
  • Status: Expired due to Fees
First Claim
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1. The method of identifying and determining the energization status of a cable operable at a given frequency and having a conductive neutral member and an internal resistive screen layer which comprises the steps of:

  • contacting said neutral member with at least a first probe;

    advancing a second probe in increments into said cable;

    injecting a test signal differing in frequency from said given frequency across said probes after each incremental advance;

    measuring the circuit resistance between said probes with a monitor after each incremental advance;

    discontinuing the advance of said second probe upon contact thereof with said screen layer evidenced by said circuit resistance falling within a predetermined range of values;

    inserting in parallel with said circuit resistance a shunt resistance of value similar to that of said circuit resistance;

    measuring the flow of current through said probes with said shunt resistance in place;

    discontinuing the injection of said test signal and disconnecting said shunt resistance upon observation of a predetermined flow of said current;

    injecting a signal of said given frequency across said probes; and

    confirming the presence of said signal of said given frequency at said monitor during the injection thereof.

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