Aircraft Electrical System Monitoring with Arc Fault Circuit Protection and Automatic Fault Location 2006-01-3091

As electrical systems on-board commercial and military aircraft grow in complexity they must also be designed for enhanced safety and functionality. Maintenance and repair become more complex, troublesome and expensive as these systems evolve.

Arcing faults occur as a result of chafing and cracking of insulation, dielectric breakdown, and looseness at terminal connections. Once arcing is initiated, damage may propagate to other conductors in the wire bundle. The discharge of arcing energy results in insulation damage, smoke events, the loss of adjacent wires in a wire bundle, and ignition of flammable materials and vapors. Such conditions have been estimated to result in approximately one unscheduled landing during an average day of air traffic worldwide, and are the primary suspects in a number of catastrophic events. Arc Fault Circuit Interrupting (AFCI) technology has been proposed as a means to improve aircraft wiring system safety. Arc Fault Circuit Breakers provide supplemental protection against arc fault conditions in addition to the thermal overload protection provided by present generation circuit breakers.

Wiring repair can be extremely expensive and time consuming, especially if the wiring is not readily accessible. With arc-fault protection the most desirable level of wiring protection will allow little damage, making troubleshooting and locating the faults more difficult. Compounding the problem is that many faults are intermittent in nature, and in locations where inspection is difficult, if not impossible. Therefore the ability to locate faults created by arcing quickly and efficiently dramatically enhances the ability of maintenance personnel to locate and correct failures, increase the availability and reliability of critical aircraft systems, and save millions of dollars in maintenance costs. An Arc-Fault protection technology enhanced with Arc Location technology can pinpoint and record the location of arc faults while providing full protection to an arc fault, and without requiring the maintenance depot to reproduce the problem.

This paper will address an approach to aircraft power system monitoring with arc fault circuit protection and automatic fault location. The proposed system can be designed to protect aircraft wiring against potentially dangerous arcing conditions and determine the location of the faults created by arcing without requiring the maintenance depot to reproduce the original problem. The paper will also discuss the benefits and advantages of implementing such a system as an important safety feature on-board commercial and military aircraft.