20140218 cisec-emc-in-aeronautics

cisec

Plus d’information à http://asso-cisec.org

2013-2014
Le lundi mardi, de 17h à 19h

Série de Conférences
Ingénierie des systèmes embarqués critiques

1- Introduction, systèmes critiques
Aéronautique (P. Traverse, Airbus, 18/11/2013)
Espace (JP. Blanquart, Astrium, 25/11/2013)
Automobile (H. Foligné, Continental Automotive, Reportée,au 11/03/2014
2- Sûreté, historique
Histoire de la sécurité du Concorde à l’A380 (JP. Heckmann, Apsys, 9/12/2013)
Comparaison de normes de sûreté (JP. Blanquart, Astrium, JM. Astruc, Continental, 16/12/2013)
3- Développement logiciel, assurance (H. Bonnin, Capgemini, 21/1/2014)
4- Développement matériel, assurance
Automobile (JP. Loncle, Continental, 28/1/2014)

Aéronautique (P. Pons, Airbus, 11/2/2014)
5- Intégration système et compatibilité électromagnétique (JC. Gautherot, ex DGA/CEAT)
Partie 1, 18/2/2014
Partie 2, 25/2/2014
6- Interactions homme-système (F, Reuzeau, Airbus, P. Palanque, IRIT, 18/3/2014)
7- Chaîne de production d’électronique pour l’automobile (Continental, 25/3/2014)
8- Diagnostic et maintenance de systèmes (Actia, 1/4/2014)
9- Systèmes autonomes dans les transports (drones, aide à la conduite automobile) (ONERA, Continental, 8/4/2014)

10- Les systèmes domotiques (R. Alami, LAAS, 15/4/2014)

CISEC: intégration systèmes et CEM phénomènes électromagnétiques

1/

SUMMARY


PART1



GENERAL CONTEXT in the AERONAUTICAL FIELD
• 1/3 Structures composite materials
• 2/3 Electronics and critical functions
• 3/3 New architectures and System evolution
ELECTROMAGNETIC PHENOMENA
• Panorama of electromagnetic phenomena and threats
• High intensity radiated field HIRF
• LIGTHNING direct effect





PART2
•
•
•

LIGTHNING indirect effect
Electromagnetic Compatibility EMC
Hardening and electromagnetic protection



APPENDIX:



Technical elements necessary to work out a financial estimate
CONCLUSION
•


2/

GENERAL CONTEXT 1/3: New Materials


COMPOSITES STRUCTURES
• Better mechanical properties
• Mass gain and improved stiffness
• Reduced delay and manufacturing process
• Maintenance (external corrosion? & Ref: refer 787 li-battery fire)
• Absorbing properties (STEALTH military aircraft)
• But poor Faraday performances (attenuation ) and poor
electrical properties VS light alloys (aluminum) i.e. grounding
and metallization problems (resistivity of carbon fiber 1000 more
greater than aluminum alloy)
• Bad electrochemical compatibility (emf: 900 mV with aluminum)
which need in particular locations the use of TITANE in order to
avoid corrosion phenomena


3/

Aircraft composites structure 1/3
B787 & A350


4/

GENERAL CONTEXT 1/3: A380 COMPOSITES


5/

Aircraft composites structure 1/3
Military aircraft & helicopter


Rafale


6/

General view of the trend to increased use of
composites materials 1/3


7/

GENERAL CONTEXT 2/3: Electronic & critical functions


Even more Electronic
•
•
•
•



FMS,GPWS,TCAS,IFE (2500 kg for A 380 2 à 3 Mips 4,7 M€)
Increased density of electronic equipment
Analogical electronic disappear for the profit all numerical electronic
Easy change thanks to embedded soft

Critical functions (no mechanical back-up)
FADEC (Engine control)
• Fly by wire (FBW)
• etc.
FREQUENCY SPECTRUM
• Up to 18 GHz or more (40 GHz)
• Increased sensitivity (ex. GPS, )
•




8/

Illustration of avionics changes 2/3:
Example of old helicopter
generation analogical Electronic
(AS 355)

Example of new helicopter (EC 725)
Numerical electronic


9/

GENERAL CONTEXT 2/3: Electronic critical functions natural
stability VS artificial which need computer operating with high safety
Fv

Fe
Aircraft with natural stability

P
Fv
Fe

P
Aircraft with artificial stability provided by electronic computer

10/

General context Frequency spectrum 2/3

Frequency spectrum in the world

Typical radio-navigation
frequencies for civil aircraft


11/

GENERAL CONTEXT 3/3: New architectures and concepts
for the aircraft system


INCREASED ELECTRIC POWER
• Even more electric actuators and less hydraulic
• Deicing & no Engine bleed air (ex B 787)
• Air conditioning compressor driven with electric motor (ex B 787)
• Mass gain (more particularly starter-generator )
• Regulations and control law more easy
• Cable routing more easy than hydraulic rigid pipes
• Improved Maintenance opposite hydraulic (drain, leakage, pollution,
fire risk….)
• but….

• Electromagnetic disturbances to be solved


12/

GENERAL CONTEXT 3/3: TREND to INCREASED ELECTRIC POWER


13/

Change in the aircraft architecture 3/3

conventionnal architecture

New architecture: example air
conditioning system driven with
electrical motor


14/

Just a look inside aircraft body: you can see……
Of course many hydraulic
pipes…..

But also even more electrical
cables (low level signal &
power supply wires)

This the reason why electromagnetic threats shall be taken into account
at the first step of the design This was the case for A 320 airworthiness
with Special condition 75 for lightning & 76 for HIRF

15/

Evolution to more electric Aircraft 3/3



BOEING 787
 95 km of cables
 More than 60 000 electrical
bonding
 40 000 cables segments
 1 500 Electrical harness
 400 optical bonding



AIRBUS A 380
 500 km of cables
 More than 9 000
connectors
 1 600 electrical harness


16/

ELECTROMAGNETIC PHENOMENA & THREATS

non-intentional

Artificial sources

Natural sources
SPIKE

HIRF
CHAMPS FORTS

Transitoires
d'alimentation

EMC

ESD

Couplage
Radioélectrique

Bruit

Tempest

Furtivité

Terrestre
Atmosphérique
Galactique
Solaire

PHENOMENES
PHENOMENES

Anticompromission

intentional

électrostatiques

Compatibilité
Electromagnétique

CRE

DES
Décharges

LEMP

CEM

ERC

FOUDRE

ELECTROMAGNETIQUES
ELECTROMAGNETIQUES

Stealth
HERP
MFP
Sécurité du

Micro-onde
Forte Puissance

IEMN
HPM
EMP

DRAM

Personnel

Dommages des rayonnements
sur armes et munitions

HERO


17/

Nuclear Electromagnetic Pulse


Generated by a High altitude
nuclear explosion






Compton effect in the atmosphere

Principal Characteristics
 bi-exponential
 Crest Amplitude 50 kV/m
 Rise time approximately:10 ns
 Half time duration 200 ns
 Capture area notion
Military system are essentially
concerned


18/

Electromagnetic tests / Electrostatic discharges


created by rubbing:
 On isolating or low
conductivity materials with low
air moisture ratio



Principal characteristics
 Bi exponential waveform
 Crest amplitude approximately
15 kV
 Rise time: some ns
 Half time duration : 20 ns


19/

Example measurement of electrostatic charging due to
blades rotation and hot gas turbine exhaust during load
winching operation for helicopter : equivalent to a capacitor
of 1nF charged up to 40 kV which can be lethal


20/

Electrostatic charges: Example of efficiency
measurement of e-discharger. The objective of the
design is to get a continuous flow of low current in order to avoid high
discontinuous high current discharges and then to reduce the noise
which can introduce disturbances & a loss of sensitivity on aircraft radio
receiver. But as we will see those devices are often damaged in the case
of aircraft lightning event


21/

Example of High Power transmitter antenna
balanced hardening notion (limit in the level of electromagnetic protection)

Military aircraft or helicopter has enough agility to avoid collision, this
is not the case for civil aircraft, in that way safety distance which are
taken into account in regulatory document are increased

Curtain antenna


22/

HIGH INTENSITY RADIATED FIELD :
Power transmitter OTHB 12 elements 1MW EIRP = 100 MW 5 to 28 MHz
41,70 N 121,18 W


23/

Some example of Incidence due to HIRF









Tornado crash in the vicinity of VOA Transmitters (was at the
origin of CS 76 for A320 Certification)
ECMU failure of Ecureuil AS 355N In the vicinity of CENTAURE
Radar
INS ALIZE MARINE Failure on Aircraft Carrier
AS332 disturbance of NG DNG T4 indicators when landing on
ship
Phone which was forget « on » in the freight compartment near
fire detector unit
Inopportune opening of hydraulic barrage gate during security
inspection due to TW emission
Don’t make confusion for turning “off “ portable computer
during take off and landing operation: it’s an EMC problem
(noise and or radio interference with radio navigation system

24/

HIGH INTENSITY RADIATED FIELD : near field for electric dipole


25/

HIGH INTENSITY RADIATED FIELD: near field for magnetic loop


26/

HIGH INTENSITY RADIATED FIELD
Example of Radiated field in the vicinity of high power transmitter

Curtain antenna 250 kW 15 MHz

Rhombic antenna 150 kW 15 MHz


27/

HIGH INTENSITY RADIATED FIELD: formulas simplification


28/

HIGH INTENSITY RADIATED FIELD: formulas
simplification substantiation


According that the
electromagnetic field in
the vicinity of antenna
vary strongly with the AC
distance and if we
observe for example the
radiation pattern of
aperture it can be seen
that the law in 1/R2 for
the value power density
is an overestimation but
conservative and then
acceptable


29/

HIGH INTENSITY RADIATED FIELD
simple formulas for field calculation field calculation
Basic formulas for a radiated electromagnetic field approximate calculation
2
P=E /Z0 W/m2
with Z0 = E/H = 120 p = 377 W
- E Electric field V/m
- H magnetic field A/m
Knowing the transmitter power and the numerical antenna gain
We can calculate the power radiated density and then the field for the distance R
2
P = GW/4 p R

E = (30GW)1/2/R
2

For Near field (if R< D /2l) this formula is majoring
l Is the wavelength in m calculated with l = f (in MHz)/ 300
D (in m) is the greatest antenna dimension en (Ex RADAR parabola diameter)
Don’t make confusion between effective mean value and effective peak value Em
For rectangular signal as for typical radar modulation with pulse duration t et
repetition time T

Em = Ec (t /T)1/2

30/

HIGH INTENSITY RADIATED FIELD:
Special condition SC76 was edited for the certification of A320


31/

value and distance


32/

average value and peak value (for RADAR modulation)


33/

acceptable method of demonstration 1/2
Acceptable methods of demonstration are :
1° low level method based on electric field attenuation measurements performed
where critical or essential equipments are located and also for the cables
induced current coming from exposed zones, thus one have 2 transfer basic
functions
After extrapolation to the external threat (linearity hypothesis) comparison of
the value obtained in laboratory test center with the value to be demonstrated.
The quantified margin between this the extrapolated value and the laboratory
value shall be positive
However this method is sometime problematic if we take into account the
representativeness of test s in the FARADAY chamber
2 high level demonstration directly on the aircraft
this method is not possible in the whole frequency domain particularly for low
frequency due to the great dimensions of civil aircraft
Example direct injection in a coaxial line for a military aircraft limited to 100 MHz


34/

demonstration methods 2/2
3° Calculation codes
Approximately valid up to 400 MHz for internal electromagnetic parameters,
but important problems to get a true representative model
In any case the model shall be validated with the help of great experimental
means associated with high performance measuring equipment on particular
points
In practice:
this different methods are combined in order to take into account:
- aircraft dimensions
- test center facilities (amplifier power and antenna gain…)
- data on similar aircraft (same technology)
- New concept and technologies
In any case it is necessary to quantify a hardening margin face to the specified
external threat. This margin shall include :
- a consumable part (putting back to initial level thanks to defined periodic
maintenance operations in order to cover wear , aging and corrosion
phenomena…)
- and a permanent part in order to cover error measurements, manufacturing
process drift etc., in order to get a good level of safety.

35/

low level method or transfer function measurement
Radiated field in the vicinity of
avionic bay

Cable induced Current
measurement probe


36/



37/

HIGH INTENSITY RADIATED FIELD: a minimum of 4
incidences and polarizations are performed for each frequency


38/

HIRF TEST PROBLEMATIC: amplitude accuracy
Taking

for example this recorded
curve where we get high resonant
and anti resonant amplitude in
relation with the frequency, in order
to get an error less than 3 db we have
to calculate the sampling by using
this formula

N=log(F2/F1)/log (1+1/Q)
 F1,

and F2 lower and upper
frequency

For

F1= 400 MHz and F2= 18 GHz for
Q= 10 a minimum of 40 frequencies
and for Q=100 382 frequencies are
necessary to cover correctly the
spectrum

39/

HIRF TEST PROBLEMATIC: data to be recorded
For a aircraft qualification we have to take into account
4 to 5 Equipment locations
10 to 20 critical or essential equipments (mean 15)
2cables minimum per equipment
4 incidences minimum
2 polarizations H et V

Consequences:

For internal radiated Field:
Frequency domain1 MHz to18 GHz
Q= 100
i.e. 984 (1000) spot frequencies
that leads to:
2x5x4x 1000 = 40 000 measurements

For wire induced current
Frequency domain10kHz à 100 MHz
Q= 10 or 100
i.e. 96 (100) or 925 (1000) spot frequencies
that leads to:
15x2x4x2x100 = 24 000 ou 240 000 measurements


40/

Danger of the non ionizing radiations:
Electric Field (thermal effects only)


41/

Danger of the non ionizing radiations: Electric Field thermal effects only
ICNIRP (International Commission on Non-Ionizing Radiation Protection)


42/

LIGHTNING STROKE from CLOUD TO GROUND


43/

Some examples of Lightning incidence & accident









Loss of 2 engines of small jet above Atlantic Sea (acoustic phenomena)
Mirage F1 of CAMBRAI AAAF Base ejector seat was energized
Helicopter replenishment service from BRISTOW ditching in north SEA
after loss of tail rotor JAN 19 1995
Personal experience during Paris Toulouse A 300 Flight and
discussion after landing: pilot tell me he was in North Sea stroked by
lightning 6 times in 10 minutes
ULM flight actuator blocked due to ARC WELDING crash follow
Amateur Video recording from tower during 747 take off

Important Studies were performed in USA by NASA F106B and
USAF with CV 580 and in France by ONERA /CEV&CEAT on Transall
C160 instrumented with electromagnetic sensor for measuring
condition of occurrences amplitude and rise time, duration time, nbr of
stroke…..

44/

Two example of Helicopter struck by Lightning
incidence & accident


45/

Different cases of aircraft lightning event to consider


Intra or inter-cloud: in those cases the aircraft in the vicinity of clouds has
triggered the arcing phenomena. it’s 80 % of lightning recorded cases. In
flight measurement (CV 580 USAF or C160 AAF in France has shown that
the amplitude is less than 40 kA)



Intercept stroke from cloud to ground: amplitude taken actually for
airworthiness authority is 200kA
Civil aircraft are struck by lightning every 4000 hrs, military: 7000 hrs




46/

Cockpit glass illumination due to high electrical field
before lightning stroke holy ELME effect


47/

LIGHTNING: result off the process electric cloud

charge
Cloud to ground Lightning process

precursors
Return stroke


48/

Lightning threat modelization


Lightning Process








Precursor (fires of the holy ELME)
Return stroke
Intermediate current
DC current
Secondary discharges

Phenomena


inter cloud & Intra cloud frequently aircraft initiated (cf. flight test CV 580 &
Transall C160)





Cloud to ground (strongest values from the contained energy point of view)

high voltage strong current and pulse repetition impossible to
generate simultaneously




Points of attachment related to the tension
Damages related to the current
Coupling related to the local densities of current (see lightning simulation
slides


49/

Definition: multiple burst / multiple stroke
LIGHTNING
attachement

Courant établi

re-attachement

Courant établi

Composante
persistante

Multiple
burst

Multiple stroke

Composante
persistante

Multiple
burst

Multiple stroke


50/

Lightning current amplitude and probability


51/

Aircraft lightning interaction: Directs & indirects effects


As it was said previously, one cannot simulate in experiments at the same time
the effects of the high electric field and the strong current; one thus studies
with large simulators the specific ones:



Direct effects








Return stroke or secondary lightning waveform A &t D
Impact of the arc, lightning currents flow
2
Structural thermo mechanical damages
Spark between poor metalized part (cover and structure) above vapor in fuel tank ( shall be
less than 200m J)

Im ax , ∫ )dt , ∫(t )dt
i (t
i

Indirect effects






multistroke, multiburst phenomena
Electromagnetic coupling
Over voltage or current surges, noise
Reversible Functional disturbances or non reversible equipment damages

di (t ) d 2 i (t ) de(t )
Im ax ,
,
,
dt
dt
dt

52/

Civil aircraft: First recorded lightning stroke
with direct effects (thermal….)


53/

Direct lightning effects on a weapon system
Illustration
of CORONA
Effect !!!

Example of
irreversible
damages


54/


55/

LIGHTNING: waveform characteristics for direct effects
current

waveform A: 1er return stroke
I max = 200 kA

i 2dt  2.10 6 A2 .s

waveform D: secondary stroke
Imax = 100 kA

waveform B: intermediate current
I mean = 2 kA

i 2 dt  0,25.10 6 A 2 .s


 idt  10C

waveform C: sustaining current
I mean = 200 A

 idt  200C
*non representative scale

< 500µs

5 ms

0,1 à 1 s

< 500µs

durée


56/

LIGHTNING Direct effect: ZONING concept


Zone 1
•
•



Zone 2
•
•



Zone 1A: initial attachment point with a low probability of arc hang on
Zone 1B: initial attachment point with a high probability of arc hang on
Zone 2A: swept zone attachment point with a low probability of arc hang on
Zone 2B: swept zone attachment point with a high probability of arc hang
on

Zone 3
•

All the other zones of the plane other than those of zones 1 and 2, there is a
low possibility of attachment of the direct arc the lightning. Surfaces of
Zone 3 can be traversed by important currents but only by direct
conduction between 2 point of initial attachment or sweeping


57/



58/



59/

Lightning as a function of Flight altitude

300-400

Civilian A/C

270-300

Military A/C

240-270
210-240
180-210
150-180
120-150
90-120
60-90
30-60
0-30
Ground
0

5

10

15

20

25


30

60/

Aircraft damages distribution
50

47,3

45
40
35
30
25

17,7

20

16,1

15

8,7

10

6,9

5,9

4,5

4

5

0,3

W
in
gs

r
ad
a
R

m
e
ad
o

ne

s
nn
a

En
gi

R

A

nt
e

ag
e
se
l

Fu

ili
s

t
St
ab

A

/C

lo
s

ag
e
da
m
o
N

er
s

0


61/

Example of lightning AIR SAFETY REPORT


62/

Example of high voltage test with MARX generator
25 stages charged at 200 kV = 5 MV
Test on instrumented mock –up in
order to study electro-charge
distribution just before first arc
junction under high electrical field

Blade attachment


63/

Effectiveness test of lightning strip diverter: Marx
generator 5 MV pek current limited to 10 kA


64/


65/

LIGHTNING direct effect:
example of radome damage


66/

cisec

Plus d’information à http://asso-cisec.org

2013-2014
Le lundi mardi, de 17h à 19h

Série de Conférences
Ingénierie des systèmes embarqués critiques

1- Introduction, systèmes critiques
Aéronautique (P. Traverse, Airbus, 18/11/2013)
Espace (JP. Blanquart, Astrium, 25/11/2013)
Automobile (H. Foligné, Continental Automotive, Reportée,au 11/03/2014
2- Sûreté, historique
Histoire de la sécurité du Concorde à l’A380 (JP. Heckmann, Apsys, 9/12/2013)
Comparaison de normes de sûreté (JP. Blanquart, Astrium, JM. Astruc, Continental, 16/12/2013)
3- Développement logiciel, assurance (H. Bonnin, Capgemini, 21/1/2014)
4- Développement matériel, assurance
Automobile (JP. Loncle, Continental, 28/1/2014)

Aéronautique (P. Pons, Airbus, 11/2/2014)
5- Intégration système et compatibilité électromagnétique (JC. Gautherot, DGA)
Partie 1, 18/2/2014
Partie 2, 25/2/2014
6- Interactions homme-système (F, Reuzeau, Airbus, P. Palanque, IRIT, 18/3/2014)
7- Chaîne de production d’électronique pour l’automobile (Continental, 25/3/2014)
8- Diagnostic et maintenance de systèmes (Actia, 1/4/2014)
9- Systèmes autonomes dans les transports (drones, aide à la conduite automobile) (ONERA, Continental, 8/4/2014)
10- Les systèmes domotiques (R. Alami, LAAS, 15/4/2014)


67/

Lightning indirect effect on complex system


68/

Lightning waveform to take into account for indirect
effect assessment
Onde A
200 kA

di/dt = 140 kA/µs
2 MJ/ohm

Onde D

100 kA

Onde H

d/dt = 140 kA/µs
0.25 MJ/ohm
Onde D/2

dI/dt = 200 kA/µs
50 kA
50 µs < dt < 1 ms

Onde B
Q = 10 C

10 kA

Onde C
200 C

30 ms < dt < 300 ms
3 fois 20 pulses

1.5 s
13 pulses


69/

From external lightning stroke to internal induced
pulses


70/

Lightning indirect effects :
From external to internal pulses
In a very simplified manner one can write :

φext (t ) = kI (t )
φ int (t ) = A( f )φext (t )
dφ int (t )
dI (t )
e (t ) =
=k
dt
dt
dI (t )
V (t ) = RI (t ) + k
dt
Homothetic form

Derivative form


71/

Typical induced waveform at equipment level
Long waveform
(A, D,D/2)

Long waveform

Fast waveform

Fast waveform
(H)

Fast waveform

Oscillatory waveform

Fast rise time= DIRAC pulse


72/


73/


74/

Functional susceptibility: incidence of the occurrence of the
pulses with respect to the computer cycle

1 pulse

many
Pulses

pulses
burst

1 erroneous bit

1 erroneous
data

many
erroneous
data

Error Detection
code

Message
repeated

equipment
declared
faulty

Necessity to achieve lightning tests on iron bird

75/

Simulator in order to inject mutiple pulses
Aircraft installation representative Cable

Equipment under test

Test
Equipement

control
computer

waveform
de
synthesizer

converter
Pulsed Power amplifier
voltage Vco


current It

76/

BASIC ELECTROMAGNETIC COUPLING
INTERNAL
ENVIRONMENT

EXTERNAL
ENVIRONMENT

I bulkhead
AGRESSION
E internal
E external

H external
I cable
Equipement

Structure


77/

External and internal Threats Modelization 2/2


Electromagnetic parameters





Electric Field E : (volt/meter)
Magnetic Field H : (amps/meter)
current:
I (amps)



Time domain: Voltage or current waveform



Frequency Domain : current or field amplitude VS frequency curves
(mean value , peak value)



Examples




LIGHTNING (LEMP): time domain current waveform
EMP: time domain electric field
HIRF: frequency domain


78/

External and internal Threats Modelization 1/2







The current means of theoretical modeling of the electromagnetic
phenomena make it possible to predict the electromagnetic
constraints intern of a system subjected to an electromagnetic
aggression
The computer code and the grid are selected according to the
accuracy which one wants to obtain for the field time/frequency that
one wants to explore
It is necessary, however, to validate the models by putting into
operation great experimental means
These great experimental means are complex of a high cost and
immobilize the system to be evaluated in a context of increasingly
tended programs


79/

Electromagnetic Simulation & Modelization 1/5: different methods


80/

Electromagnetic Simulation & Modelization 1/5: different methods 2/5: advantages
& drawback of each methods


81/

Electromagnetic Simulation & Modelization 3/5: examples for lightning
probability


82/

Example Lightning current distribution on
the structure (arc between aircraft nose and right wing)


83/

Electromagnetic Simulation & Modelization : theoretical demonstration

in seven

steps experimentation/validation

du modèle


84/

Experimental simulation on mock up
limited to external phenomena applications examples: antenna pattern, ESR






It is possible in particular cases as for aero dynamical model in wind tunnel (cf.
Reynolds number) to perform measurement at reduced scale
However some electromagnetic law for similarity shall be applied in order to be
representative
Non linear phenomena are not taking into account such as :
 Hysteresis
 Magnetic Saturation
 Ionization
It’s necessary to reproduce skin effect dielectric & magnetic losses






emf2= e’m’f’2/r2
smf = s’m’f’/r2

If the tests are achieved in the same surrounding (see mock up inthe following table
then e = e’ et m = m’
In particular cases conductivity can not be enough increased (problem of copper Vs
aluminum and also ground for which it’s necessary to inject salt with water solution)


85/

Electromagnetic law for experimental simulation on
mock-up at reduced scale
parameter

Real system

reduced scale

Mock up

Length

L ( meter)

l’ = l/r

L’ = L/r

Time

T (second)

t’ = t/g

t’ = t/r

Electrical field

E (V/m)

E’ = E/a

E’ = E/a

Magnetic field

H (A/m)

H’ = H/b

H’ = H/a

Magnetic permeability

m (H/m)

m’  m x (rb/ga)

m’  m

permittivity

e (F/m)

e’  e x (ra/bg)

e’  e

Electrical conductivity

s (W/m)

s’  s x (ra/b)

s’  s x r

voltage

V (V)

V’ = V /(ra)

V’ = V /(ar)

current

I (A)

I’ = I /(br)

I’ = I /(ar)

Surface current

J (A/m2)

J’ = J/b

J’ = J/a

frequency

f (hertz)

f’ = f x g

f’ = f x r

Résistance

R (W)

R’ = R x (b/a)

R’ = R

Inductance

L (Henry)

L’ = L x (b/ag)

L’ = L/r

Capacitance

C (Farad)

C’ = C x (a/bg)

C’ = C/r


86/

Example of Antenna characterization on typical mock up


87/

Electromagnetic phenomena & threats
CEM
Aptitude d’un dispositif, d’un équipement ou d’un système à
fonctionner de façon satisfaisante dans son environnement
électromagnétique sans produire lui même des perturbations
électromagnétiques intolérables pour tout ce qui se trouve dans cet
environnement

EMC
The ability of equipments (or Systems) to operate satisfactorily in its
electromagnetic environments without introducing intolerable
disturbances to anything in that environment

jean-charles.gautherot@wanadoo.fr


88/

ELECTRO MAGNETIC COMPATIBILITY
Definition & related basic documents






Electromagnetic disturbance is any phenomenon that may
degrade the performance of a device, equipment, or system or
adversely affect living or inert matter
DO 160 F (equipment) for civil aircraft
MILSTD 461 E (equipment) & MIL STD 464 (system) for military
qualification
And many other documents: FCC, IEC , CISPR…….OTAN
document (AETCP 500 & 250) including French document in the
past such as GAM EG13 (AIR 7306 for military aircraft)


89/

COUPLING MODE

EMITTER
CULPRIT

interconnexion

RECEIVER
VICTIM

masse

supply
radiation : (wire, antenna or aperture) towards (wire, antenna or aperture)
conduction : towards supply or interconnecting cables


90/

4 basic tests ref:
DO 160 (for civil aircraft) & MILSTD 461 (for military aircraft)

CEM
Emission
CE
Section 19

Susceptibilité
RE
Section 21

CS
Section 18 & 20

RS
Section 20


91/

Fundamental principle of the CEM: trilogy
A

B

EMITTER
CULPRIT

RECEIVER
VICTIM

COUPLING

Negative margin
Positive margin

Emission level

Susceptibility level

B disturbed

B non disturbed
frequency


92/

CEM: example limit for radiated emission taking into
account radio receiver sensitivity an not only intrinsic EMC


93/

EMC: Type of signal which are measured, spectrum in
frequency domain (radiation or conduction)
There are narrow band signal and broadband signal (d is pulse duration at 50% &T is
rise and fall time between 10 & 90 %)
Example of unique ( non repetitive ) pulse spectrum
amplitude in frequency domain is given for example in dBm or dBµV/m or dBµA /Hz
Time to frequency representation


94/

EMC: BROADBAND or NARROWBAND ? Measurements value will vary
with the width of the filter used with the spectrum analyzer


95/

EMC: measurement specification


In order to avoid misinterpretation in the value of amplitude measurement
results, bandwidth filter and time between each frequency step used for
emission are defined in normative document for different frequency band
measurement. Example


96/

What’s About PED ?

MAXIMUM VALUES
L e v e l, d B u V /m

Measured PEDs
WB Switching Power Supplies
and Video Dis play Sweeps

95
85
75
65
55
45
35
25
1E-2

1E-1

NB Local Oscillators
and Clocks

1E0
1E1
1E2
Frequency, MHz

1E3

1E4


97/

CEM & PED: front door and back door coupling


Front-Door coupling
PED Undesired Emissions Coupled Through Fuselage Windows and Door
Seams to Radio, Navigation, and Radar Antennas (receiving mode) transmodulation effect

•

•
•
•
•
•
•
•
•
•
•
•


•
•

75 MHz: Marker Beacons
108-136 MHz: ILS Localizer, VDT, VOR, VHF Com, VDL
329-335 MHz: ILS Glide Slope
962-1215 MHz: DME (Military TACAN)
982 MHz: ADS-B UAT
1030, 1090 MHz: ATC & TCAS
1530-1610 MHz: Satellite Com
1575.42 MHz: GPS
4200-4400 MHz: Radar Altimeter
5030-5090 MHz: Microwave Landing System
5350-5470, 9300-9500, 15500-15700 MHz: Weather Radar

Back-Door Coupling
PED Undesired Emissions Coupled to Avionics Boxes
PED Undesired Emissions Coupled to Avionics Wiring


98/

CEM: example of equipment conducted
emission measurement
Power supply switching fondamental & harmonics

Microprocessor


99/

CEM: Example of radiated emission measurement


100/

CEM: Example of radiated susceptibility measurement
in RADAR frequency domain on FADEC


101/

Test with Reverberating chamber by using cavity resonance
frequencies (starting only above 6 times the first low resonance frequency
can be used for radiated susceptibility but also for emission tests)

Testing equipment or System

Calibration for the Em. FIELD


102/

Example of Specific test which are not
included in aeronautical norm or specification




This helicopter was used by
EDF for the maintenance of
electric line and the
cleaning with KARCHER of
Isolators
The objective of test was to
see if there is no misoperating of ECMU under
High voltage & high
magnetic field at low
frequency (50 Hz)


103/

ELECTROMAGNETIC PROTECTION:
don’t forget embedded software


Software example: ECMU (Electronic control motor unit)







Tolerances
accuracy (prediction of periodic maintenance)
Gradient test
Consistency test
Numeric filtering

Consequences



Many features
Opposite part:
• Response time
• Memory size


104/

ELECTROMAGNETIC PROTECTION:
overview of basic protections












Shielding
Bonding
Grounding
Clamping
Filtering
Segregation
Optical fiber link
Clean and dirty zones design
Balanced Hardening concept
And….


105/

Protection device:typical filter structure
Linear filter are commonly used to protect equipment against the adverse effect of wire
induced current in the frequency domain or of power switching supply rejected
signal . Different structure are possible taking into account simultaneously source
and load impedances in order to get the maximum mismatching


106/

Example of filter attenuation curve for different structure and of cells Nbr

Note: in general cases attenuation curve are given for nominal value of source and load resistance
but in the real practice it’s never the case in a large frequency domain


107/

Example of different filter set-up
Coaxial structure reduce connection inductance


108/

Basic limitation of filter
For the correct design of filters there are important parameter to take into
account


For inductance:
– Serial resistance (loss of nominal supply voltage)
– Parasitic capacitance between wounding (high frequency limitation)
– saturation of ferromagnetic material due to permanent supply current CC or CA
– Ferromagnetic losses (EDDY current et hysteresis cycle)
– Ferromagnetic material maxi temperature en temperature coefficient



For capacitance:
– Parallel resistance (leak current)
– Serial inductance of connection (high frequency limitation)
– Breakdown voltage CC et CA
– Diverted current for CA supply
– Dielectric losses
– Dielectric material maxi temperature en temperature coefficient


109/

Non linear devices basic set for protection in the time domain


110/

Non linear protections: typical value of different devices such as zener
diodes, varistor or gaz spark


111/

Time domain pulses: in order to get a safe design, hypothesis of matching
of source and load resistance is taken (max transmitted energy)


112/

Electromagnetic protection devices: design rules

Protection against time
domain threat:
•LEMP
•NEMP
•ESD

Protection against
frequency domain threat:
•HIRF
•HPM


113/

PROTECTION DEVICES
COMPREHENSIVE & CONSISTENT HARDENING CONCEPT


114/

Appendix
Electromagnetic environment and tests

Information necessary for a technical and
commercial proposal


115/

Technical elements necessary to work out an estimate
System Or
Equipment
Under test

Test
Program

Technical
&
Commercial
proposal

Configurations

Furniture's


116/

System or equipment under test









Equipment overall dimensions
 Maximum ground metallic plane and direction of radiation VS
equipment aircraft positionning
Blowing/Cooling
 Air or fluid Flow
 intermittent operation or not
Power supply
 Permanent & peak power
 Start current
Cabling (representativeness)
 Access, Break boxes
Equipment mass
 Handling (support, mounting)
 Maximum load on floor and on ground metallic plane


117/

Equipment under test : configuration


How many Configurations ?
 Different operating modes
– Example:
» light or full load (computer must operate and acquire external signal & data
coming from sensors or simulators
» Fault detection
» susceptibility: signal of sensor adjusted to low tolerance value
» emission: signal of sensor adjusted to high tolerance value
» Energized or not or both
 Software

Version
– Specific test or true and last flight version
 Cables
 With or without over shielding

118/

TEST PROGRAM


Applicable norms and documents





Severity and test procedures
Progressive increase of test level ( 3dB? 6dB?….)
Test file
– From most severe to less severe : objective to get asap first results
to modify the equipment

– From less severe to most severe : demonstration to the buyer that
first results are already positive


Correct operation checking before, during and after,
tests



Acceptable or not susceptibility criteria definition
Necessity to identify the origin of dysfunctions or
breakdowns


119/

Furnitures/constraints


Stimulis




Means necessary to obtain representative operation
– availibility
– Particular software test
– BUS access for spying data flow without disturbances

Instrumentation



sensors: voltage, current, position, temperature etc.
Internal accessibility


120/

CONCLUSION






Information's described previously very seldom appears in the
request for proposal or are incomplete
They are however necessary to determine the feasibility of the
all tests which is not always acquired
They have a direct impact over the duration of tests and thus on
the cost
the customer does not control all subtleties of the tests within a
program. The tests center must also play the part of council

Before providing a credible offer, one, even
several meetings with the customer are
necessary to tackle the problems mentioned
above

121/

CONCLUSION &……. QUESTIONS
According to the field
of frequency to be treated
Used tools
for simulation
will not be the same ones

Necessity for designing
electromagnetic
protections
in comprehensive &
Consistent manner

Whatever
computer code has been used
It is necessary to validate
the ideal model
using
large Experimental
simulators

about the functional level:
Role of the HARDWARE
and SOFTWARE:
Attention with the differences
Between the TEST version for
laboratory
and the real embedded Version

80 to 90%of disturbances
come from cables
Future:
Optical numeric BUS
but mechanical, thermal
properties
and maintenance
to be improved


122/

And perhaps for next CISEC conference cycle !!!


123/

20140218 cisec-emc-in-aeronautics

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