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Load current monitoring device for detecting predetermined degree of change in load impedance

  • US 4,539,562 A
  • Filed: 12/30/1982
  • Issued: 09/03/1985
  • Est. Priority Date: 12/30/1982
  • Status: Expired due to Fees
First Claim
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1. A device for detecting changes in load impedance by detecting changes in load current that are not induced by fluctuations in the applied load voltage comprising:

  • means for monitoring the current provided to the load, said current monitoring means providing a dc voltage signal having an amplitude proportional to the amount of load current;

    means for monitoring the voltage applied to the load, said voltage monitoring means providing another dc voltage signal having an amplitude proportional to the amount of load voltage; and

    means responsive to said dc signals, said responsive means comparing a value indicative of the monitored current to a preset reference value, the said value indicative of the monitored current being corrected prior to said comparing by means of a correction signal derived from the monitored voltage to negate the effect on the value indicative of monitored current of fluctuations in the load voltage, the said responsive means indicating a predetermined change in load current relative to said reference value resulting solely from a predetermined change in load impedance.

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