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Harmonic measuring instrument for AC power systems with a time-based threshold means

  • US 5,300,924 A
  • Filed: 08/21/1992
  • Issued: 04/05/1994
  • Est. Priority Date: 08/21/1992
  • Status: Expired due to Fees
First Claim
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1. An apparatus for measuring voltage harmonics and current harmonics on an alternating current power system comprising:

  • a. means for sensing a predetermined harmonic voltage parameter and a predetermined harmonic current parameter coupled to the alternating current power system;

    b. means for comparing the harmonic voltage parameter to a predetermined voltage threshold and for comparing the harmonic current parameter to a predetermined current threshold coupled to the means for sensing;

    c. means for calculating a first time parameter during which the predetermined voltage threshold was exceeded by the harmonic voltage parameter and a second time parameter during which the predetermined current threshold was exceeded by the harmonic current parameter coupled to the means for comparing; and

    d. means for indicating when either the first time parameter or the second time parameter exceed a predetermined time threshold.

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