Patent ID: 7554324

Claim:
A turbine blade proximity control system for controlling proximity of each of a plurality of turbine blades to a non-rotating turbine component, comprising: a sensor coil; an oscillator circuit including one or more capacitance circuit elements electrically coupled in parallel with the sensor coil to thereby form a parallel-resonant LC tank circuit having a resonant frequency that varies with the proximity of the sensor coil to each of the turbine blades, the oscillator circuit operable to generate and supply a sensor signal having a frequency that varies based on the resonant frequency of the parallel-resonant LC tank circuit, whereby the sensor signal is a frequency modulated sensor signal; a frequency modulation (FM) demodulator adapted to receive the frequency modulated sensor signal and operable, in response thereto, to supply a proximity signal having an amplitude that varies with, and is representative of, the proximity of each of the turbine blades to the non-rotating turbine component; and a controller coupled to receive the proximity signal from the frequency modulation demodulator and operable, in response thereto, to control the proximity of the turbine blades to the non-rotating turbine component.