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 comPSmith@LiveWireTest.com

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/~cfursecfurse@ece.utah.edu

IEEE APS 6-20-03