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Equipment fail safe safety system

  • US 7,543,170 B2
  • Filed: 09/30/2004
  • Issued: 06/02/2009
  • Est. Priority Date: 09/30/2004
  • Status: Expired due to Fees
First Claim
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1. A safety circuit for monitoring and controlling power to an equipment operated by a computer executing control software to cause said equipment to “

  • fail safe”

    in the event of a safety alert, said safety circuit comprising;

    a detector circuit for receiving an alternating state telemetry signal from said computer, wherein said alternating state telemetry signal indicates a satisfactory operation of said computer and said control software;

    a relay circuit for applying power to said equipment;

    a first counter, coupled to said detector circuit, for outputting a first alert signal to said first relay circuit in response to an interruption in said alternating state telemetry signal received by said detector circuit;

    a second counter for outputting a reset signal to cancel said first alert signal in response to a resumption of said alternating state telemetry signal being received by said detector circuit in less than a predetermined timeout period after said interruption, thereby preventing said safety circuit from removing power from said equipment; and

    a switching circuit, coupled to said detector circuit, for switching said relay circuit to remove power from said equipment in response to said interruption lasted longer than said predetermined timeout interval.

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