Temperature compensated eddy current sensor temperature measurement in turbine blade shroud monitor

DETAILED DESCRIPTION The present invention is directed to a system for monitoring the temperature of a plurality of turbine blade shroud segments.
Each shroud segment carries indicia.
A sensor produces input signals in response to the indicia.
A temperature sensor measures the temperature of the sensor producing the input signals.
A first circuit, responsive to the temperature sensor, corrects the input signals to compensate for the effects of temperature on the sensor.
A second circuit determines the temperature of each shroud segment based on the corrected input signals.
According to one embodiment of the present invention the first circuit may multiply the input signal by a correction factor.
The correction factor is based on the temperature of the sensor producing the input signals and may be obtained from a look-up table or by evaluating an equation which expresses the correction factor as a function of the temperature of the sensor producing the input signals.
According to another embodiment of the present invention the second circuit determines the temperature of each shroud segment based on the magnitude of the corrected input signals.
A look-up table may store various shroud segment temperatures corresponding to various magnitudes of the corrected input signal.
Alternatively, an equation expressing shroud segment temperature as a function of the magnitude of the corrected input signal may be evaluated.
The present invention is also directed to a method for monitoring the temperature of a plurality of turbine blade shroud segments comprising the steps of: sensing eddy currents generated in each shroud segment as a result of indicia carried by each shroud segment to produce input signals; measuring the temperature of the eddy current sensor; correcting the input signals based on the temperature of the eddy current sensor to compensate for the effects of temperature on the eddy current sensor; and determining the temperature of each shroud segment based on the corrected input signals