The Next Generation of TDR Technology

Non-Contact Connections for Reflectometry and Location of Faults in Cable Shields

The following slides were presented at the 2012 Aircraft Airworthiness & Sustainment Conference in Baltimore, Maryland on April 4, 2012. To view all slides, view the .PDF.
Non-Contact Connections for Reflectometry and Location of Faults in Cable Shields: Dr. Cynthia Furse, Dr. Brian Jones, Lucas Thomson

 

Time delay between Incident and Reflected Pulses tells distance to fault. The challenge: MANY faults cannot be replicated on the ground. Tests can't interfere with aircraft signals and aircraft signals can't interfere with tests.

 

TDR: Time  -  FDR: Frequency  -  NDR: Noise  -  STDR: Spectral  -  SSTDR: Spread Spectrum

 

'Hard' Fault is an open/short or near open/short that produces a LARGE electrical change to the system and produces a LARGE reflection to reflectometry. A 'Soft' Fault is caused by small impedance changes (corrosion, water, aging materials, etc.) and it produces a SMALL (maybe undetectable) electrical change to the system and it produces a SMALL reflection ot reflectometry.

 

'Hard' Fault: Open/Short or Near Open/Short  -  'Soft' Fault: Small impedance changes (corrosion, water, aging materials, etc.)  -  'Intermittent' Fault: Any fault (large or small) that appears and then disappears with time; 'Dry Arc' (vibration/stress induced; 'Wet Arc' (Moisture induced); 'No Fault Found"

 

Miswire: 8%; Failure due to corrosion: 7%; Short due to corrosion: 1%; Unspecified Failure: 6%; Short circuit unspecified cause (includes arcing incidents): 3%; Loose connection: 2%; Insulation failure: 3%; Chafed wire insulation leading to short circuit and/or arcing: 32%; Connector Failure: 9%; Broken Wires: 10%; and Other: 18%

 

Simulated Wire: TDR Signal & Partial wire fault location (high impedance short) with partial signal reflection due to a high impedance short circuit.

 

Live testing can locate up to 72% of wiring failures. Broken wires: 10%; Connector failure: 9%;  Miswire: 8%; Failure due to corrosion: 7%; Short due to corrosion: 1%; Unspecified failure: 6%; Short circuite unspecified cause (includes arcing incidents): 3%; Loose connection: 2%; Insulation failure: 3%; Chafed wire insulation leading to short circuit and/or arcing: 32%; and Other: 18%

 

During this 1 minute test, LiveWire SSTDR arc fault technology detected and reported the fault location more than 15 times prior to AFCB trip.

 

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About

Dr. Cynthia Furse is the Associate Vice President for Research at the University of Utah and a Professor of Electrical and Computer Engineering. Dr. Furse received her Ph.D. in electrical engineering from the University in 1994. She has taught electromagnetics, wireless communication, computational electromagnetics, microwave engineering, antenna design, and introductory electrical engineering. Dr. Furse is a Fellow of the IEEE. She was the Engineering Department's Distinguished Professor 2008, Distinguished Young Alumnus, Professor of the Year in the College of Engineering at Utah State University in the year 2000, and the Faculty Employee of the Year 2002. She received the IEEE Harriett B. Rigas award in 2009. Dr. Furse has directed the Utah “Smart Wiring” program, sponsored by NAVAIR, NASA, and USAF, since 1998. She has 9 patents, over 170 professional publications, and has written two books.

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