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State of the ArtState of the Art –Live Wire Testingg
Dr. Paul Smith, Dr. Cynthia FurseLiveWire Test Labs IncLiveWire Test Labs, Inc.
Salt Lake City, Utah
Paul Smith, Cynthia Furse, “State of the Art in LiveWireTesting,” Joint FAA/DoD/NASA Conference on Aging Aircraft, J 31 F b 3 2005 P l S i CAJan 31-Feb 3, 2005, Palm Springs, CA
State of the Art Live Wire Testing State of the Art Live Wire Testing
Paul Smith (LiveWire Test Labs, Inc.), Cynthia Furse (University of Utah and LiveWire Test Labs, Inc.)
A lot of effort has gone into testing wires on the ground. While this is important, certain problems remain undetectable in an unpowered system Tests and theoretical analysis show that problems such as wet and dryundetectable in an unpowered system. Tests and theoretical analysis show that problems such as wet and dry arcs, loose pins, chafing, etc. can only be detected while an aircraft is powered and/or in flight. This leads to high maintenance costs for a large percentage of aircraft wiring system anomalies.
There is significant hesitancy to use arc fault circuit interrupters (AFCI’s) on aircraft even though they will make the aircraft safer. Part of the problem is that if an AFCI trips on an arc event, the damage is so small that it is p p gvirtually undetectable on the ground even through close visual inspection. With the expectation of false trips, it will be difficult to know if a trip event represents a real problem or a ghost.
Advances in spread spectrum wire testing continue to improve the ability to detect and to pinpoint the location of wet arcs, dry arcs, exposed conductors in condensation, and other intermittent and hard fault events. By
ti l it i t i i i t t d t i it b k h f th ti dcontinuously monitoring system wiring using smart connectors and smart circuit breakers, much of the time and effort spent finding intermittent faults on the ground can be eliminated. Tests have been performed on wires carrying DC, AC power, and data bus communication signals with real aircraft loads without mutual interference. Accurate distance to fault information has been reported even with faults on branched wiring
networks and short circuits to airframenetworks and short circuits to airframe.
Traditional Methods Work Well IF Wire is OPEN or SHORT
AFCI Wet Arc Test
What About Frays and Arcs?
LiveWire Locates Faults while the Wire and Fault are LIVE
When a drop of water creates a wet arcWhen a drop of water creates a wet arc, it is a SHORT CIRCUIT for a few millisecondsmilliseconds.
LiveWire Locates Faults while the Wire and Fault are LIVE
Less than 1 ohm impedance changechange…
When the water is gone, the faulti t ll t d t t W tis too small to detect. We mustlocate it in the few ms it is a SHORT.
To Run LIVE: Electronic Hardware Form Factor NonInterference with Aircraft Signals Realistic Wire Environment
Realistic aircraft loads Controlled / Uncontrolled Impedance Cables Branched Wires
Data Collection and Interpretation
2003003
2004-5
2007
2005
2007
2006
Livewire & Minnesota Defense
New Board Developmentp Preliminary Specs from USAF SBIR Phase I First pass hardware from FAA BAA First pass hardware from FAA BAA Packaging by Minnesota Defense
Arc Fault Circuit Interrupter Reduces Size of Fault But How can youSize of Fault But How can you LOCATE it?
10 A Thermal Breaker Tripped AFCI Tripped on “Wet Arc”10 A Thermal Breaker Tripped AFCI Tripped on Wet Arc
To Run LIVE: Electronic Hardware Form Factor NonInterference with Aircraft Signals Realistic Wire Environment
Realistic aircraft loads Controlled / Uncontrolled Impedance Cables Branched Wires
Data Collection and Interpretation
To Run Live: NonInterference with Aircraft SignalsNonInterference with Aircraft Signals
Superimpose a tiny PN code signal that looks likeLiveWire S/SSTDR Technology
Superimpose a tiny PN code signal that looks like noise on the existing signal.
Test LIVE to catch intermittent faults while they Test LIVE to catch intermittent faults while they are near open or short circuits.
STDR: Sequence TDR
PN Code
q
PN Code unknowntime shift
×
∫ PN Code knowntime shift
SSTDR: Spread Spectrum TDR“Super Stealthy TDR”
PN Code
p pSuper Stealthy TDR
PN Code unknowntime shift
×
∫PN Code knowntime shift∫
STDR
To Run LIVE: Realistic Aircraft Loads
D A (G ill ti T t)Dry Arc (Guillotine Test)120’ uncontrolled impedanceWire with STROBE Light
d 400 H Pand 400 Hz Power.
To Run LIVE: Electronic Hardware Form Factor NonInterference with Aircraft Signals Realistic Wire Environment
Controlled / Uncontrolled Impedance Cablesp Realistic aircraft loads Branched Wires
Data Collection and Interpretation
Uncontrolled Impedance Cable
To Run LIVE: Realistic Aircraft Loads
Dry Arc (Guillotine Test)120’ t ll d i d120’ uncontrolled impedanceWire with LANDING GEAR Light and RETRACTION MOTOR 400 H PMOTOR 400 Hz Power.
To Run LIVE: Wet Arc
Tests in Presence of Noise1
0.2
0.4
0.6
0.8
1
STDR test with fluorescent lampat 60 Hz, arc test with branchednetwork, arc at end of 12 ft branch.T t ith l h d t h
−0.6
−0.4
−0.2
0Test with slow hardware catchespart of arc.
0.4
0.5
−40 −20 0 20 40 60 80 100−0.8
SSTDR test with fluorescent lampat 60 Hz arc test with branched
0
0.1
0.2
0.3at 60 Hz, arc test with branchednetwork, arc at end of 8 ft branchTest with slow hardware catchespart of arc.
−40 −20 0 20 40 60 80 100−0.3
−0.2
−0.1
To Run LIVE:Must be able to handle BRANCHEDMust be able to handle BRANCHED Circuits
0.66Mismatchat Feed
-0.33 Open Circuit1.0
at Feed
Short Circuit-1.021
ZZZZ
21 ZZ
Branched Wire Mapping Network R i d ( d U fU d l )Required (under UofU development)
STDRFDR
FDRFDR
FFT of FDR
TDR
SSTDR
LiveWire System 2007Data Acquisition OptionsData Acquisition Options
S Pl t Lightning ProtectionSmart Breakers
LRU
Sensor Placement Lightning ProtectionSmart Breakers
Comm Link ConnectorsBranched Networks
Handheld / GUI
To Run LIVE: Electronic Hardware Form Factor NonInterference with Aircraft Signals Realistic Wire Environment
Realistic aircraft loads Controlled / Uncontrolled Impedance Cables Branched Wires
Data Collection and Interpretation
2003003
2004-5
2007
2005
2007
20062006Livewire/Minnesota Defense
We would like to Thank our Partners
Dr. Paul SmithLiveWire Test Labs, Inc.PSmith@LiveWireTest [email protected]
Questions ?
© All rights reserved. No part of this presentation may be copied or reused
ith t itt i i f thwithout express written permission of the authors. Contact:Dr. Cynthia Furse
www.ece.utah.edu/[email protected]
IEEE APS 6-20-03