ASIC Implementation of Live Arc Fault SSTDR Tester

Arc Fault Circuit Breaker (AFCB) technology promises to minimize the destruction of wiring elements in aircraft caused by potentially dangerous arcing events. While AFCB technology can enhance aircraft wiring protection, it creates significant difficulties for the aircraft maintainer who must find the barely visible arc-traces and repair the causes of these arc fault events. Intermittent faults are very difficult to find using traditional fault location methods as they tend to hide by having the wiring system become fullyoperational, usually when the maintainer is trying to locate the faults. What is needed is a set of tiny instruments that can be built into the critical electrical systems throughout the aircraft that can detect and locate arc-faults and intermittent problems on live wires. LiveWire Test Labs, Inc., in conjunction with the US Air Force, US Navy, Sensata Technologies, and Minnesota Defense is developing an Application Specific Integrated Circuit (ASIC) with embedded Spread Spectrum Time Domain Reflectometry (SSTDR) technology for the detection and location of faults in complex electrical wiring systems. The SSTDR technology is capable of monitoring powered wiring systems arcs and intermittent shorts without interfering with either power transmission or communication signals. It can detect arcs on live wires that last 250 microseconds or more by continuously monitoring the test wire (most arc events last about 500 microseconds). Signals from an AFCB will detect the arc fault and trigger the SSTDR ASIC to capture the event live for future analysis. The projected power usage for the new SSTDR fault detection system is approximately 350 milliwatts. Faults can typically be located to +/-1.5 feet over 100 feet of wire/cable, but the system may be adjusted to optimize these distances. Preliminary test data on the prototype Wiring In-Line Maintenance Aid (WILMA) will be presented on intermittent fault data on live and un-powered wires. The new ASIC is designed to fit into an 8mm x 8mm package. This implementation allows a complete instrumentation system to be constructed in a footprint smaller than a quarter. The size and weight of this instrumentation allows many such devices to be placed throughout the aircraft with minimal impact with respect to size and weight. The ASIC is expected to generate a new series of chip based instrumentation products that promise more accuracy and reliability at a very cost effective price. This new SSTDR ASIC, in conjunction with WILMA and the AFCB, should bring major benefits to aviation by reducing wiring based accidents, reducing maintenance time, and at the same time reducing the cost of maintaining aircraft. 1 LiveWire Test Labs, Inc., 5330 S 900 E, Suite 150, Salt Lake City, UT 84117 2 Univ. of Utah Dept. of Electrical and Computer Engineering, 50 S Campus Drive, Salt Lake City, UT 84112 3 Sensata Technologies, 529 Pleasant St., MS B-53, Attleboro, MA 02703 4 Minnesota Defense/Minnesota Wire & Cable, 1835 Energy Park Drive, St Paul, MN 55108 Dr. Paul Smith, Dr. Paul Kuhn, Michael Diamond, Dr. Cynthia FurseSrini C. Sekar, Lynn Edmunds, Tom Kukowski, “ASIC Implementation of Live Arc Fault SSTDR Tester,” Joint FAA/DOD/NASA Conference on Aging Aircraft, www.agingaircraft2008.com, April 21‐24, 2008, Phoenix, Arizona Page 2 of 11