Detecting a failure in a thermocouple array
A method of monitoring a health of a temperature system may comprise selecting a temperature sensor of a plurality of temperature sensors arranged in an array, where each temperature sensor corresponds to an address within the array. The method may comprise identifying the address corresponding to the single temperature sensor, sending the address to a multiplexer, and selecting the single temperature sensor using the identified address. The method may comprise testing the selected single temperature sensor calculating an average temperature detected by the plurality of temperatures sensors.
1 . A method of monitoring a health of a temperature system location, the method comprising:
choosing a single temperature sensor of a plurality of temperature sensors to test, wherein the plurality of temperature sensors are arranged in an array, each of the plurality of temperature sensors corresponding to an address within the array;
identifying, via a controller, the address within the array corresponding to the single temperature sensor;
sending the identified address to a multiplexer connected to the plurality of temperature sensors;
selecting, via the multiplexer, the single temperature sensor using the identified address;
testing, with the controller and a testing circuitry comprising an impedance determination circuit, for a closed-circuit failure mode of the selected single temperature sensor by at least detecting for a shift in impedance of the selected single temperature sensor;
cycling through each one of the plurality of temperature sensors, repeating the choosing, identifying, sending, selecting, and testing for each of the plurality of temperature sensors; and
calculating an average temperature of a location containing the plurality of temperature sensors using individual temperature measurements of the plurality of temperature sensors.
2 . The method of claim 1 , further comprising removing, with the controller, the individual temperature measurements of one or more temperature sensors of the plurality of temperature sensors for which the shift in impedance is detected from the average temperature calculation.
3 . The method of claim 1 wherein the array comprises the plurality of temperature sensors arranged in parallel.
4 . The method of claim 1 wherein the array is disposed in an exhaust stage or in a combustor stage of a gas turbine engine.
5 . The method of claim 1 wherein the controller is a full authority digital engine control (FADEC) of a gas turbine engine.
6 . The method of claim 1 further comprising selecting and testing each one of the plurality of temperature sensors individually at regular intervals.
7 . The method of claim 1 further comprising indexing through and testing each one of the plurality of temperature sensors upon receipt of a calibration instruction.
8 . The method of claim 1 , wherein the testing further comprises connecting the single temperature sensor to one or more nodes of a Wheatstone bridge.
9 . A temperature measurement system, the system comprising:
a plurality of temperature sensors arranged in an array, wherein each of the temperature sensors has a corresponding respective address;
a multiplexer in selective communication with each one of the plurality of temperature sensors to select a single temperature sensor of the plurality of temperature sensors;
test circuitry configured to test for a closed-circuit failure mode of the single temperature sensor, wherein the test circuitry comprises an impedance determination circuit configured to connect to the single temperature sensor and detect for an impedance shift of the single temperature sensor; and
a controller in communication with the multiplexer and the test circuitry, wherein the controller is configured to, responsive to the test circuitry detecting the impedance shift, isolate the single temperature sensor from the plurality of temperature sensors.
10 . The system of claim 9 wherein the array is disposed in a combustor stage of a gas turbine engine.
11 . The system of claim 9 wherein the array is disposed in an exhaust stage of a gas turbine engine.
12 . The system of claim 9 wherein the controller is a full authority digital engine control (FADEC) of a gas turbine engine.
13 . The system of claim 9 , wherein the impedance determination circuit comprises a Wheatstone bridge.
14 . The system of claim 13 , wherein the impedance determination circuit further comprises a comparator circuit.
15 . The system of claim 14 , wherein the impedance determination circuit further comprises an excitation circuit.
16 . A method of monitoring a health of a temperature system, the method comprising:
choosing a single temperature sensor of a plurality of temperature sensors to test, wherein the plurality of temperature sensors arranged in an array, each of the plurality of temperature sensors corresponding to an address within the array;
identifying the address within the array corresponding to the single temperature sensor;
sending the identified address to a multiplexer connected to the plurality of temperature sensors;
selecting, via the multiplexer, the single temperature sensor using the identified address;
testing the selected single temperature sensor for a closed-circuit failure mode by at least detecting for a shift in an impedance of the selected single temperature sensor with testing circuitry;
detecting a closed-circuit failure mode of the tested temperature sensor based on the shift in the impedance and identifying the selected single temperature sensor to a controller; and
cycling through, using the controller and multiplexer, each one of the plurality of temperature sensors, repeating the testing for each sensor.
17 . The method of claim 16 further comprising calculating an average temperature detected by the plurality of temperatures sensors, wherein any detected failed temperature sensor is removed from the average temperature calculation.
18 . The method of claim 16 further comprising repeatedly cycling through and testing each one of the plurality of temperature sensors at regular intervals.
19 . The method of claim 16 further comprising signaling a maintenance alert when a failure of one of the plurality of temperature sensors is identified.
20 . The method of claim 16 , wherein the testing further comprises connecting the single temperature sensor to one or more nodes of a Wheatstone bridge.