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Polyphase angle estimator

  • US 4,398,255 A
  • Filed: 06/26/1981
  • Issued: 08/09/1983
  • Est. Priority Date: 06/26/1981
  • Status: Expired due to Fees
First Claim
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1. A power system relay for rapidly detecting multiphase faults in transmission lines comprising:

  • means having an input of the multiphase voltage and currents of said transmission line for generating a polarizing signal and an operating signal for each input phase;

    a first summing means;

    means for multiplying the polarizing signal relating to one phase by the operating signal relating to the same phase and coupling the result for each phase to a different positive input of said summing means;

    means for generating a signal indicative of the average amplitude of all said polarizing signals;

    means for generating a signal indicative of the average amplitude of all said operating signals; and

    means for multiplying said average polarizing signals and said average operating signals together and adjusting the product by a predetermined gain, said gain determining the balance angle between phases, said adjusted product being coupled to a negative input of said summing means,said summing means output indicating an abnormal condition when it is above a predetermined value.

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