Electric arc detection for probe heater PHM and prediction of remaining useful life
A system for an aircraft includes an aircraft component that includes a heater routed through the aircraft component, the heater including a resistive heating element and insulation surrounding the resistive heating element. A first current flows into the resistive heating element to provide heating for the aircraft component and a second current flows out of the resistive heating element. The system further includes a first sensor configured to produce a first sensor signal representing the first current, a second sensor configured to produce a second sensor signal representing the second current, a leakage sensor configured to produce a leakage sensor signal representing a leakage current, and a signal processor configured to sample and measure the first current, the second current, and a leakage current using a high frequency sampling rate to identify the presence of electric arcing. The detection of electric arcing is used to predict future heater failure and estimate heater remaining useful life.
1. A system for an aircraft, the system comprising:
an aircraft component that includes a heater routed through the aircraft component, the heater comprising:
a resistive heating element; and
insulation surrounding the resistive heating element;
wherein a first current flows into the resistive heating element to provide heating for the aircraft component and a second current flows out of the resistive heating element;
a first sensor configured to produce a first sensor signal representing the first current;
a second sensor configured to produce a second sensor signal representing the second current;
a leakage sensor configured to produce a leakage sensor signal representing a leakage current; and
a signal processor configured to sample and measure the first current, the second current, and a leakage current using a high frequency sampling rate to identify the presence of electric arcing.
2. The system of claim 1 , further including a prediction processor configured to determine future heater failure based on the electric arcing.
3. The system of claim 1 , further including a prediction processor configured to determine remaining useful life of the aircraft component.
4. The system of claim 1 , further including a prediction processor configured to identify the presence of electric arcing in the heater based on high frequency noise in the first current and the second current.
5. The system of claim 1 , wherein the signal processor is configured to digitize the first sensor signal, the second sensor signal, the leakage sensor signal, and a difference voltage, the difference voltage being the difference between the first sensor signal and the second sensor signal.
6. The system of claim 1 , wherein the signal processor is configured to amplify the leakage sensor signal.
7. The system of claim 1 , wherein the signal processor samples the first sensor signal, the second sensor signal, and the leakage sensor signal at a frequency of about 150 KHz to about 500 KHz.
8. The system of claim 1 , wherein the signal processor filters the first sensor signal, the second sensor signal, and the leakage sensor signal to a frequency range from about 50 KHz to about 200 KHz.
9. The system of claim 1 , further including a prediction processor configured to predict a remaining useful life of the heater based on the signatures and magnitudes of Fourier transformed data representing the first sensor signal, the second sensor signal, and the leakage sensor signal.
10. The system of claim 1 , wherein the signal processor is configured to output Fourier transformed data representing the first sensor signal, the second sensor signal, and the leakage sensor signal.
11. The system of claim 10 , further including a prediction processor configured to identify a future short circuit or a future open circuit based upon the Fourier transformed data representing the first sensor signal, the second sensor signal, and the leakage sensor signal.
12. The system of claim 10 , further including a prediction processor configured to identify a future open circuit when the Fourier transformed data representing the first sensor signal and the second sensor signal indicate high frequency noise and the leakage sensor signal is not elevated.
13. The system of claim 10 , further including a prediction processor configured to identify a future short circuit when the Fourier transformed data representing the first sensor signal and the second sensor signal indicate high frequency noise, the Fourier transformed data representing the leakage sensor signal also indicates high frequency noise, and the leakage sensor signal is elevated.
14. The system of claim 10 , wherein the signal processor is configured to output Fourier transformed data representing the difference between the first sensor signal and the second sensor signal, which is equal to the leakage sensor signal.
15. The system of claim 1 , wherein the heater further comprises a metallic sheath surrounding the insulation such that the insulation is between the resistive heating element and the metallic sheath.
16. The system of claim 1 , further comprising a voltage source to provide the first current to the resistive heating element.
17. The system of claim 1 , wherein the first current and the second current provided to the resistive heating element may be AC or DC power.
18. The system of claim 1 , wherein the first sensor is a first sense resistor, the second sensor is a second sense resistor, and the leakage sensor is a leakage sense resistor.
19. The system of claim 1 , wherein the signal processor samples the first sensor signal, the second sensor signal, and the leakage sensor signal at a frequency greater than two times the highest frequency of electrical noise produced by electric arcing.
20. The system of claim 1 , wherein the aircraft component is an air data probe.