CEA LIST

Utilisation de la
réflectométrie pour fiabiliser
les câbles d’un système
Contact :
CEA LIST
Mr Josy COHEN – Responsable de projet &
ingénieur chercheur
[email protected]
+33 1 69 08 78 07
www.cea.fr
&
CEA pour
experience
in cable
diagnosis
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Our Laboratory :
LFIC : Laboratoire Fiabilité et Capteurs Intégrés
More than 10 years experience and knowledge in
network cable diagnosis
CEA policy :
To create breakthrought
to take advantage and to create new jobs
by industrial transfer
for French companies
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Ubiquitous
wired
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stylenetwork
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Civil plane
Modern Car
40
4
1
10
Fighter
200
100
Naval
1200
400
km
2500
1000
10000
FPSO
Railway
(Floating Production, Storage and Offloading unit)
&
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wire
NPP
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le defects
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Température
Humidité
Exposition des
couches intérieures
Conducteur et
Contacts:
Corrosion
Isolation :
Electrical Tree
Changement
de couleur et
durcissement
Fentes dans
l’isolation
Radiation
Effet sur
l’isolation
Rupture de Liaisons
 Radicaux Libres
&
Liaison des radicaux libre
 Changement des propriétés du
matériel
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Some
wire
defects
Underwater
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Développement
d’organismes vivants
Développement
d’anèmones
Grappin de bateau
de pèche
Frottement contre
des roches
Ancres
&
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Main causes of degradation on electrical wire :
Submarine
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titre
Around more than 100 detected failure for the
submarine wire
Proportion des causes de défaut
entre 1959 et 2006 sur 2162 entrées
(Tyco Telecommunications Inc)
&
Causes des défauts jusqu’à 200m
de profondeur par an
(Wood and Carter - IEEE 2008)
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defects
: aeronautic
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&
Frottement
Arc Electrique
Ecrasement
Rayon de courbure
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Main causes of degradation on electrical wire :
Cliquez pour modifier le styleAeronautics
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 With open circuit or short circuit, the
system are out of order
 Chafing defect more important than open
or short circuit in ratio.
 With time, Chafing transforms the defect in
open or short circuit
&
 Wires with its connectors are the main
cause of accident
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Some consequences
wiredu
failures
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A plane staying on the ground cost $150.000 by hour
(Boeing)
TGV delay cost around 750€ by minute
(SNCF)
Swissair flight 111
Fire on board made by short-circuit in electrical
wires
TWA fligth 800
Explosion made by short-circuit near fuel tank
&
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to ?
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du titre
Visual control
Long, tedious
Human error
Continuity test
Straightforward tools
No localization
Thermography
Too slow
Open circuit not cover
Reflectometry
Cost
Real time
Easy to operate and to integrate
&
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: Principle
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Like a radar!
Injection of a probe signal in a wire
Probe signal propagation
Each wire strangeness leads a reflection of a part of the probe signal
energy
… the reflected signal is analyzed
An echo occurs for each wire strangeness
Possible defect information is given by the echo shape
A defect “flight time” could be obtain
Corresponding to the defect localization (distance)
The propagation speed estimation is a key parameter
&
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: Principle
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The reflectometry principle is related to the signal propagation mechanism
into a transmission line (TL)
S
Parallel
ZL
dx
Torsade
Coaxial
i(x) R  dx
 Modeling and characterization of a TL
G  dx
v(x)
i( x  dx)
L  dx
 R, L, C, G Model
v( x  dx)
C  dx
 based on Telegrapher's equations
x
 to figure out how a signal is propagated into a TL
Telegrapher's equations
 we have to look signal distortion phenomenon
 Attenuation and dispersion
x  dx
 2v( x, t )
 2v( x, t )
v( x, t )
 LC 
 ( LG  RC ) 
 RG  v( x, t )
2
2
x
t
t
Zc 
&
R  jL 
G  jC
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Vg 
1
LC
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: Principle
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Injection Plan
Cable end
Zc: characteristic impedance
Probe signal
S
ZL
Reflected signal
 Probe signal travelling along a line and returning
with a delay equivalent to two times the defect
distance
TDR Reflectograms
0.5
Incident
wave
Onde
incidente
Circuit ouvert
150 Ohms
75 Ohms
50 Ohms
25 Ohms
Court-circuit
Reflected
wave
Onde réfléchie
0.4
Amplitude en V
0.3
d
0.2
0.1
2 L  vg
2
0
-0.1
 Defect (ZL) localization and characterization are
obtained directly from the reflectograms analysis in
the time domain
-0.2
2 L
-0.3
-0.4
-0.5
-0.5
0
&
0.5
1
Temps en s
1.5
2
2.5
x 10
-7
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: Principle
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Particular cases:
ZL = ∞ : ΓL =+1, open circuit – The amplitude of the reflected signal is
similar to the probe signal one
ZL = 0 : ΓL = -1, short circuit – The amplitude of the reflected signal is
the opposite of the probe signal
ZL = Zc : ΓL = 0, no reflexion – The line is suitable
Z L  Zc
L 
Z L  Zc
&
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CEAle
Breakthrought
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Some new technologies developed
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styledistance
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Adaptive correlation for performance enhancement :
Sensitivity
Railway signalization cable , reel length : 2km
&
Measure
Standard correlation
Adaptive correlation
Amplitude (V)
0.1
0.18
0.59
Localization (m)
2260
2257
2073
Relative error
13%
13 %
3.7 %
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Onleline
Diagnosis
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MCTDR (Multicarrier Time Domain Reflectometry)
Probe signal corresponds to a sum of sine curves
The probe signal spectrum is controllable by cancelling the desired
carried signal
Safe diagnosis : Harmless ness
EMC Compliance
Low sensitivity to SNR
MCTDR in TRL > 5
&
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Complex
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Distributed-MCTDR
S2
V1
V2
S1
V3
S3
The reflectometry distribution is obtained with a weighted mean process allowing a
cross-correlation between reflectometers.
Multi-sensing strategy allowing to avoid the ambiguity.
A specific tool is proposed to facilitate the reflectometer
deployment and to simulate the diagnosis strategy
&
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Technology
integration
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Avionic
DIAGNOCHIP, a 3 mm2 130nm
integrated reflectometer
 A mixed Analog/Digital IP for real
time processing
 5cm resolution (4GHz guided
wavelength)
Railway
Solar power
&
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CEAle
Breakthrought
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Some new technologies in progress
&
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Reflectometry
softdu
defect
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
External source of failure
 Mechanical stress
 Assembly errors
 Corrosion, oxidation
 Effect of environment s

Internal source of failure
 Manufacturing errors
 Wear-out defect
 Local hot-spot
Wear type
Primary signs
Detection method
Overheating of the wire
Wear zone
Visual inspection
Reflectometry
Bad contact
Change in impedance
Local hot spot
Thermal, Point by point test
Reflectometry
Intermittent short circuit faults
Electromagnetic Magnetic Interference
Electric arc
Visual inspection
Reflectometry
Short circuit faults
Circuit-breaker system
Reflectometry
Broken insulation
Crack, damaged area
Visual inspection
Reflectometry
Exposed conductor
Loss of the function
Fire
Visual inspection
Reflectometry
Corrosion
Loss of signal or data
Visual inspection
Reflectrometry
Humidity
Loss of signal or data
Reflectometry
Wear out and/or Loss of the function
Local alteration of R, L, C, G parameters
Local alteration of the characteristic impedance Zc
Local alteration of the propagation speed
&
ΓL ≠ 0
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

Open defect
Soft defect
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Reflectometry
softdu
defect
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Injection Plan
Cable end
Localized defect Zd
Zc: characteristic impedance
Probe signal
S
T
Transmitted signal
Reflected signal
Parallel defect
Serial defect
0.5
0.45
0.3
Short
circuit
Court-circuit
25 Ohms
50 Ohms
75 Ohms
100 Ohms
125 Ohms
Open circuit
Circuit
ouvert
Reflected wave
by the cable end
Amplitude [V]
0.2
Short
circuit
Court-circuit
25 Ohms
50 Ohms
75 Ohms
100 Ohms
125 Ohms
Open circuit
Circuit
ouvert
0.4
Reflected wave
by the cable end
0.35
0.3
Amplitude [V]
2 D
0.4
0.1
0
-0.1
Reflected
by the defect
0.25
0.2
0.15
2 L
-0.2
-0.3
0.1
0.05
Reflected
by the defect
-0.4
0
0.5
&
1
Temps [s]
1.5
2
x 10
0
0
0.5
-7
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1
Temps [s]
1.5
2
x 10
-7
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Soft defect
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detection
CliquezSoft
pourdefect
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One of our advance post processing for soft defect signature
amplification
1
1
reflectogramme initial
reflectogramme traité
Simulation
0.8
Soft defect
Soft defect
0.4
0.2
0.4
0.2
0
0
-0.2
-0.2
-0.4
Cab_224b
Twisted pair (5 m) - Shielded - AWG24 0.25mm²
Soft defect = sheath + shield (pulled out) 2cm
0.6
Amplitude
Amplitude
0.6
reflectogramme initial
reflectogramme traité
Experimentation
0.8
0
1
2
3
Distance(m)
4
5
6
-0.4
1.2
0
1
2
3
Distance(m)
4
5
6
1
reflectogramme initial
reflectogramme traité
Open wire
1
Adapted wire
0.8
End of cable
0.6
0.8
reflectogramme initial
reflectogramme traité
End of cable
Coaxial cable RG58CU (3.20 mètres)
Soft defect = sheath + shield (pull out) 2cm
0.4
Amplitude
Amplitude
0.2
0.6
0.4
Soft defect
0
-0.2
Soft defect
-0.4
0.2
-0.6
0
-0.8
-0.2
&
0
0.5
1
1.5
2
Distance(m)
2.5
3
3.5
-1
0
0.5
1
1.5
2
Distance(m)
2.5
3
3.5
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Blind
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style method
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Interconnection
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Signal
injection
Cable under test
Signal
injection
Cable connection and junction characterization
30cm
50Ω
87Ω
Zc = 75 Ω Coaxial
0,1% real part
1-2% imaginary part
ld = 30 cm
V² = 4,65
Likelihood ratio
 To characterize interconnection or connector (database)
 To diagnosis soft defect in the interconnection
&
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RLCG extract
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Cable
and
aging characterization
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Cable characterization by RLCG parameters extraction
Coaxial (5 m) Zc = 75 Ω
V² = 3,7
Likelihood ratio
Aging characterization
New
Aged
Coaxial (9,8 m) Zc = 75 Ω
&
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CEAle
Breakthrought
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And for the next future
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CEAle
Breakthrought
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All these new technologies and know how in LFIC
What are the new technologies for the future ?
Which new application domain ?
 Use a cable like environement sensor (temperature,
humidity, …)
 New application domain : SHM
CEA is aware about industrials needs
&
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Merci pour votre
attention
Centre de Grenoble
17 rue des Martyrs
38054 Grenoble Cedex
Centre de Saclay
Nano-Innov PC 172
91191 Gif sur Yvette Cedex