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Combined current and voltage transformer for a metal-enclosed gas-insulated high-voltage switching station

  • US 5,432,438 A
  • Filed: 06/26/1992
  • Issued: 07/11/1995
  • Est. Priority Date: 06/29/1991
  • Status: Expired due to Term
First Claim
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1. A combined current and voltage transformer for metal-enclosed, gas-insulated high-voltage switchgear comprising:

  • a tubular metal enclosure at ground potential and filled with an insulating gas;

    a current sensor enclosed and supported by said enclosure and containing a shielded Rogowski coil, which after installation in the metal enclosure concentrically surrounds a high-voltage conductor of the switchgear;

    a voltage sensor enclosed and supported by said enclosure and containing a hollow cylindrical test electrode which after installation in the metal enclosure concentrically surrounds the high-voltage conductor of the switchgear and which is part of a capacitive voltage divider containing;

    a high-voltage capacitor formed by the high-voltage conductor and the test electrode;

    a low-voltage capacitor formed by the test electrode and the metal enclosure as well as the shield of the Rogowski coil; and

    an ohmic resistor having a first end electrically connected to the test electrode and having a second end electrically connected to the metal enclosure and the shield of the Rogowski coil for forming signals at the output of the voltage sensor which are proportional to the temporal variation in the high voltage of the high voltage conductor; and

    a signal processing device connected to the current sensor and to the voltage sensor and having at least one integration device on which the output signals of the current sensor and of the voltage sensor act

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