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Harmonic monitor and protection module

  • US 5,319,513 A
  • Filed: 10/17/1991
  • Issued: 06/07/1994
  • Est. Priority Date: 10/17/1991
  • Status: Expired due to Fees
First Claim
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1. A monitor used in detecting malfunctions of at least one tuned harmonic filter in an electrical system, comprising:

  • sensing means for obtaining a signal from the filter, representative of the electrical condition within the filter, and being connected to a coil of the filter for three-phase monitoring and comparison between phases;

    at least two monitoring circuits, a first monitoring circuit for detecting volt-second product of the filter at a fundamental frequency and detecting changes in the filter thereby, and a second monitoring circuit for detecting volt-second product at harmonic frequencies and detecting changes in the filter thereby;

    at least two timing circuits operatively connected to said two monitoring circuits, a first timing circuit for producing a signal when abnormal conditions are detected, and for delaying disconnection of the system to permit a rechecking of the abnormal conditions, and a second timing circuit for disconnecting the filter from the system when rapid operation of the disconnection is needed to prevent damage; and

    indicator means for signalling a particular condition in the filter;

    said disconnection resulting in the filter being disconnected from the system and said indicator means being illuminated.

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