A capacitive probe for quantitative nondestructive evaluation of wiring insulation

Abstract A capacitive probe has been developed for quantitative evaluation of wiring insulation permittivity. The probe consists of two patch electrodes that conform to the curvature of the wire under test. A numerical model is utilized for inverse determination of insulation complex permittivity from measured probe response. Experimental studies on thermally and hydrolytically degraded wire samples show that the resulting permittivity change of the insulation is successfully detected using the described capacitive probe, for the wire type MIL-W-81381/12, which is predominantly Kapton ® coated. Changes in the permittivity of the wiring insulation, detected by the capacitive probe, are shown to be in accordance with the results of research conducted previously on Kapton ® film samples degraded by thermal and hydrolytic exposure. Thus, the feasibility of assessing wiring insulation degradation status by quantitative capacitive techniques is demonstrated, which is of particular interest to the aerospace industry.

[1]  You Chung Chung,et al.  Capacitance and Inductance Sensor Circuits for Detecting the Lengths of Open- and Short-Circuited Wires , 2009, IEEE Transactions on Instrumentation and Measurement.

[2]  Cynthia Furse,et al.  A critical comparison of reflectometry methods for location of wiring faults , 2006 .

[3]  Robert E. Green,et al.  Nondestructive testing of aircraft and spacecraft wiring , 2003 .

[4]  Nicola Bowler,et al.  Analysis of Arc-Electrode Capacitive Sensors for Characterization of Dielectric Cylindrical Rods , 2012, IEEE Transactions on Instrumentation and Measurement.

[5]  K. Brown,et al.  Selection of Wavelet for De-noising PD waveforms for Prognostics and Diagnostics of Aircraft Wiring , 2008, 2008 Annual Report Conference on Electrical Insulation and Dielectric Phenomena.

[6]  N. Bowler,et al.  Analysis of a capacitive sensor for the evaluation of circular cylinders with a conductive core , 2012 .

[7]  I. Sava,et al.  Dielectric behavior of some aromatic polyimide films , 2011 .

[8]  Cynthia Furse,et al.  Down to the wire [aircraft wiring] , 2001 .

[9]  J. Russell,et al.  Aqueous degradation of polyimides , 1971 .

[10]  D. Koltsov,et al.  Failure mechanisms of legacy aircraft wiring and interconnects , 2008, IEEE Transactions on Dielectrics and Electrical Insulation.

[11]  Paul Smith,et al.  Spread spectrum sensors for critical fault location on live wire networks , 2005 .

[12]  Cynthia Furse,et al.  Down to the wire , 2001 .

[13]  Larry K. Baxter,et al.  Capacitive Sensors: Design and Applications , 1996 .

[14]  B. A. Auld,et al.  Capacitive Arrays for Robotic Sensing , 1987 .

[15]  John C. Moulder,et al.  Characterization of capacitive array for NDE applications , 1990 .

[16]  M. R. Kessler,et al.  Influence of thermal degradation and saline exposure on dielectric permittivity of polyimide , 2011 .

[17]  You Chung Chung,et al.  Application of phase detection frequency domain reflectometry for locating faults in an F-18 flight control harness , 2005, IEEE Transactions on Electromagnetic Compatibility.

[18]  C. Furse,et al.  Analysis of spread spectrum time domain reflectometry for wire fault location , 2005, IEEE Sensors Journal.

[19]  F Anastasi Robert,et al.  Ultrasonic Guided Waves for Aging Wire Insulation Assessment , 2001 .

[20]  C. Furse,et al.  Feasibility of spread spectrum sensors for location of arcs on live wires , 2005, IEEE Sensors Journal.

[21]  Cynthia Furse,et al.  Frequency-domain reflectometry for on-board testing of aging aircraft wiring , 2003 .

[22]  Tianming Chen,et al.  Analysis of a concentric coplanar capacitive sensor for nondestructive evaluation of multi-layered dielectric structures , 2010, IEEE Transactions on Dielectrics and Electrical Insulation.