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Steam turbine blade arrival time processor with automatic gain control

  • US 5,015,949 A
  • Filed: 12/22/1988
  • Issued: 05/14/1991
  • Est. Priority Date: 12/22/1988
  • Status: Expired due to Fees
First Claim
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1. An apparatus for precisely detecting the passing of an individual blade of a rotating machine past a stationary sensor, comprising;

  • stationary magnetic sensor means for producing an input signal of substantially constant magnitude each time the blade passes said sensor means;

    automatic gain control means responsive to said input signal for regulating the amplitude of said input signal to a predefined nominal value;

    zero-crossing detection means for producing an output signal in response to said regulated input signal each time said regulated input signal crosses a reference axis;

    means for producing a gating signal coinciding with an expected arrival time of the blade at said sensor means wherein said means for producing said gating signal includes a first comparator for receiving said regulated input signal at a first input terminal thereof and for receiving a first reference signal at a second input terminal thereof, said gating signal being available at an output terminal thereof;

    gate means responsive to said gating signal for conducting said output signal which occurs during the expected arrival time of the blade at said sensor means;

    flip-flop means for propagating said gating signal to said gate means until such a time as said flip-flop means is cleared; and

    means responsive to said conducted output signal for producing a pulse coinciding with the time at which the blade passes said sensor means.

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