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Ground conductor monitoring system

  • US 4,368,498 A
  • Filed: 07/09/1980
  • Issued: 01/11/1983
  • Est. Priority Date: 03/20/1979
  • Status: Expired due to Term
First Claim
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1. A ground conductor monitoring system for use with a cable system having power conductors carrying electrical power between a source and a load and a ground conductor connecting the source and the load to each other comprising:

  • a transmitter toroid surrounding the ground conductor, a transmitter coil wound on the transmitter toroid, a transmitter driving the transmitter coil with a monitoring a-c signal and a booster coil also wound on the transmitter toroid and having said monitoring signal induced therein;

    a filter electrically connecting one side of the booster coil to the source side of the power conductors and passing said monitoring signal but not said power, a filter connecting the load side of the power conductors to the load side of the ground conductor and passing said monitoring signal but not said power, and an electrical connection between the other side of the booster coil and the source end of the ground conductor;

    whereby the ends of the booster coil are connected to each other through a series circuit comprising the ground conductor, the load side filter, the power conductors and the source side filter, and said monitoring signal induced in the booster coil flows through said series circuit;

    a monitor toroid also surrounding the ground conductor and a monitor coil wound on the monitor toroid to have induced therein said monitoring signal flowing in the ground conductor, and a monitor coupled with the monitor coil and responsive to an interruption in the monitoring signal induced in the monitor coil to generate a tripping signal indicative of a possible discontinuity in the ground conductor.

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