Steam turbine blade arrival time processor with automatic gain control
First Claim
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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Accused Products
Abstract
An apparatus for detecting turbine blade passing times includes a sensor for producing an input signal each time a blade passes the sensor. Automatic gain control circuitry including a digital multiplier, peak detector and error amplifier regulates the amplitude of the input signal. A zero-crossing detector produces an output signal each time the input signal crosses a reference axis. A pre-trigger comparator produces a gating signal coinciding with the expected arrival time of the blade at the sensor. A gating device is responsive to the gating signal for conducting output signals which occur during the expected arrival time of the blade at the sensor. A monostable vibrator produces a digital pulse coinciding with the time at which the blade passes the sensor.
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Citations
11 Claims
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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;
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus for precisely detecting the passing of an individual blade of a rotating machine past a stationary sensor, comprising:
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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 a digital output signal in response to said regulated input signal each time said regulated input signal crosses a reference axis; means for producing a digital gating signal coinciding with an expected arrival time of the blade at said sensor means wherein said means for producing said digital 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 digital gating signal being available at an output terminal thereof; gate means responsive to said digital gating signal for conducting said digital output signal which occurs during the expected arrival time of the blade at said sensor means; flip-flop means for propagating said digital gating signal to said gate means until such time as said flip-flop means is cleared; and means responsive to said conducted output signal for producing a digital pulse coinciding with the time at which the blade passes said sensor means.
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Specification