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May 22, 2017 | Cabling systems: detecting defects before a failure occurs

List CEA Tech
© Nicomatic

List, a CEA Tech institute, has developed the first-ever industrial-scale reflectometry-based embedded early cable defect detection demonstrator system.

When it comes to aircraft cabling systems, early-stage defects account for 45 % of damage-inducing faults. And yet, traditional reflectometry techniques are mainly useful in detecting dead shorts. A system to detect early-stage defects would let aircraft maintenance technicians attend to these defects before they generate faults.

The demonstrator developed by List leverages a circuit board that injects an orthogonal multi-tone time domain reflectometry (OMTDR) signal into the cabling system. When the signal passes through a defective area, some of its energy is sent back to the injection point, while the rest continues to propagate throughout the system. The circuit board creates the reflectogram from the data, and then uses an innovative algorithm protected by several patents to fuse the results from several post-processing methods to provide robust, multi-criteria diagnostics. Another benefit is that a master circuit board can communicate with additional slave circuit boards that send their own reflectograms, resulting in an even more precise combined analysis.

The demonstrator system can detect smaller insulation and shielding defects on twisted-pair and twisted-quad cables than current detection systems. For example, the system picked up a 5 mm-long shielding defect and a bend radius of ten times or less than the cable's diameter during testing, a world-first. The compact system can be integrated into connectors to build self-diagnosing complex cable assemblies. The demonstrator system was presented at a conference and will soon be scaled-up by Nicomatic for manufacturing.