20140218 cisec-emc-in-aeronautics

CISEC: intégration systèmes et CEM phénomènes électromagnétiques 1/

cesic cesic2013-2014

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)

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

http://asso-cisec.org/




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


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


Aircraft composites structure 1/3

B787 & A350


GENERAL CONTEXT 1/3: A380 COMPOSITES


Aircraft composites structure 1/3

Military aircraft & helicopter

Rafale


General view of the trend to increased use of

composites materials 1/3


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, )


Illustration of avionics changes 2/3:

Example of old helicopter

generation analogical Electronic

(AS 355)

Example of new helicopter (EC 725)

Numerical electronic


GENERAL CONTEXT 2/3: Electronic critical functions natural

stability VS artificial which need computer operating with high safety

Aircraft with natural stability

Aircraft with artificial stability provided by electronic computer

P

P

Fv

Fv

Fe

Fe


General context Frequency spectrum 2/3

Frequency spectrum in the world

Typical radio-navigation

frequencies for civil aircraft


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


GENERAL CONTEXT 3/3: TREND to INCREASED ELECTRIC POWER


Change in the aircraft architecture 3/3

conventionnal architecture

New architecture: example air

conditioning system driven with

electrical motor


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


Evolution to more electric Aircraft 3/3

AIRBUS A 380

500 km of cables

More than 9 000 connectors

1 600 electrical harness

BOEING 787

95 km of cables

More than 60 000 electrical bonding

40 000 cables segments

1 500 Electrical harness

400 optical bonding


ELECTROMAGNETIC PHENOMENA & THREATS

PHENOMENES

ELECTROMAGNETIQUES

DES

Décharges

électrostatiques

Bruit

Terrestre

Atmosphérique

Galactique

Solaire

DRAM

Dommages des rayonnements

sur armes et munitions

Transitoires

d'alimentation

CEM

Compatibilité

Electromagnétique

MFP

Micro-onde

Forte Puissance

IEMN

Artificial sources

FOUDRE

Natural sources

inte

nti

on

al

SPIKE

HERO

EMC

LEMP

ESD

HPM

EMP

Stealth

CHAMPS FORTS

HIRF

Sécurité du

Personnel

HERP

PHENOMENES

ELECTROMAGNETIQUES Anticompromission

Furtivité

no

n-i

nte

nti

on

al

Tempest

CRE

Couplage Radioélectrique

ERC


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


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


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


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


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


HIGH INTENSITY RADIATED FIELD : Power transmitter OTHB 12 elements 1MW EIRP = 100 MW 5 to 28 MHz

41,70 N 121,18 W


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


HIGH INTENSITY RADIATED FIELD : near field for electric dipole


HIGH INTENSITY RADIATED FIELD: near field for magnetic loop


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


HIGH INTENSITY RADIATED FIELD: formulas simplification


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


HIGH INTENSITY RADIATED FIELD

simple formulas for field calculation field calculation

Basic formulas for a radiated electromagnetic field approximate calculation

P=E2/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

P = GW/4 p R2

E = (30GW)1/2/R

For Near field (if R< D2/2l) 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


HIGH INTENSITY RADIATED FIELD:

Special condition SC76 was edited for the certification of A320



value and distance


HIGH INTENSITY RADIATED FIELD: average value and peak value (for RADAR modulation)


HIGH INTENSITY RADIATED FIELD: 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



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.


HIGH INTENSITY RADIATED FIELD: low level method or transfer function measurement

Radiated field in the vicinity of

avionic bay

Cable induced Current

measurement probe


HIGH INTENSITY RADIATED FIELD: a minimum of 4

incidences and polarizations are performed for each frequency


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


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 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

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


Danger of the non ionizing radiations:

Electric Field (thermal effects only)


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

ICNIRP (International Commission on Non-Ionizing Radiation Protection)


LIGHTNING STROKE from CLOUD TO GROUND


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…..


Two example of Helicopter struck by Lightning

incidence & accident


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


Cockpit glass illumination due to high electrical field

before lightning stroke holy ELME effect


LIGHTNING: result off the process electric cloud

charge

Cloud to ground Lightning process precursors

Return stroke


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


attachement Courant établi re-attachement Courant établi

Multiple

burst

Multiple

burst

Multiple stroke Multiple stroke

Composante

persistante Composante

persistante

Definition: multiple burst / multiple stroke

LIGHTNING


Lightning current amplitude and probability


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

Structural thermo mechanical damages

Spark between poor metalized part (cover and structure) above vapor in fuel tank ( shall be

less than 200m J)

Indirect effects

multistroke, multiburst phenomena

Electromagnetic coupling

Over voltage or current surges, noise

Reversible Functional disturbances or non reversible equipment damages

( ) ( ) ( )

dt

tde,

dt

tid,

dt

tdi,axIm

2

( ) ( )dtti,dtti,axIm 2∫∫


Civil aircraft: First recorded lightning stroke

with direct effects (thermal….)


Direct lightning effects on a weapon system

Illustration

of CORONA

Effect !!!

Example of

irreversible

damages


LIGHTNING: waveform characteristics for direct effects

current

durée

waveform B: intermediate current I mean = 2 kA

idt 10C

waveform C: sustaining current I mean = 200 A

idt 200C

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

i2dt 2.10

6A2.s

waveform D: secondary stroke Imax = 100 kA

i2dt 0,25.10

6A2.s

< 500µs 5 ms 0,1 à 1 s < 500µs

*non representative scale


LIGHTNING Direct effect: ZONING concept

Zone 1

• 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 2

• 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


Lightning as a function of Flight altitude

0 5 10 15 20 25 30

Ground

0-30

30-60

60-90

90-120

120-150

150-180

180-210

210-240

240-270

270-300

300-400Civilian A/C

Military A/C


Aircraft damages distribution

47,3

0,3

5,98,7

17,7

4

16,1

4,56,9

0

5

10

15

20

25

30

35

40

45

50

No

damag

e

A/C

lost

Sta

bilise

rs

Fusela

ge

Ant

ennas

Eng

ine

Rad

ome

Rad

ar

Win

gs


Example of lightning AIR SAFETY REPORT


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


Effectiveness test of lightning strip diverter: Marx

generator 5 MV pek current limited to 10 kA


LIGHTNING direct effect:

example of radome damage


cesic cesic2013-2014

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)

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





Lightning indirect effect on complex system


Lightning waveform to take into account for indirect

effect assessment

10 kA

50 kA

100 kA

200 kA

3 fois 20 pulses

30 ms < dt < 300 ms

Onde H

50 µs < dt < 1 ms

Onde Adi/dt = 140 kA/µs

2 MJ/ohm

Onde BQ = 10 C

Onde Dd/dt = 140 kA/µs

0.25 MJ/ohm

Onde D/2

13 pulses

1.5 s

Onde C200 C

dI/dt = 200 kA/µs


From external lightning stroke to internal induced

pulses


Lightning indirect effects :

From external to internal pulses

( ) ( )

( ) ( ) ( )

( )( ) ( )

( ) ( )( )

dt

tdIktRItV

dt

tdIk

dt

tintφdte

textφfAtintφ

tkItextφ

+=

==

=

=

Homothetic form Derivative form

In a very simplified manner one can write :


Long waveform

Fast waveform

Fast waveform

Oscillatory waveform

Long waveform

(A, D,D/2)

Fast waveform

(H)

Typical induced waveform at equipment level

Fast rise time= DIRAC pulse


Functional susceptibility: incidence of the occurrence of the

pulses with respect to the computer cycle

1 pulse many

Pulses

pulses

burst

1 erroneous bit

Error Detection

code

Message

repeated

1 erroneous

data

equipment

declared

faulty

many

erroneous

data

Necessity to achieve lightning tests on iron bird


Simulator in order to inject mutiple pulses

computer

Equipment under test

control

Pulsed Power amplifier

waveform

de

synthesizer

converter

voltage Vco current It

Aircraft installation representative Cable

Test

Equipement


BASIC ELECTROMAGNETIC COUPLING

EXTERNAL

ENVIRONMENT

INTERNAL

ENVIRONMENT

AGRESSION

E external

H external

Equipement

E internal

I cable

I bulkhead

Structure


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


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


Electromagnetic Simulation & Modelization 1/5: different methods


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

& drawback of each methods


Electromagnetic Simulation & Modelization 3/5: examples for lightning

probability


Example Lightning current distribution on

the structure (arc between aircraft nose and right wing)


Electromagnetic Simulation & Modelization : theoretical demonstration in seven

steps experimentation/validation

du modèle


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)


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


Example of Antenna characterization on typical mock up


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

[email protected]


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)



COUPLING MODE

interconnexion

masse

supply

radiation : (wire, antenna or aperture) towards (wire, antenna or aperture)

conduction : towards supply or interconnecting cables

EMITTER

CULPRIT

RECEIVER

VICTIM



4 basic tests ref:

DO 160 (for civil aircraft) & MILSTD 461 (for military aircraft)

CEM

Emission Susceptibilité

CE

Section 19

RE

Section 21

CS

Section 18 & 20

RS

Section 20


Fundamental principle of the CEM: trilogy

EMITTER

CULPRIT

RECEIVER

VICTIM COUPLING

Emission level

Susceptibility level

frequency

A B

B disturbed B non disturbed

Positive margin

Negative margin


CEM: example limit for radiated emission taking into

account radio receiver sensitivity an not only intrinsic EMC


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


EMC: BROADBAND or NARROWBAND ? Measurements value will vary

with the width of the filter used with the spectrum analyzer


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


What’s About PED ?

25

35

45

55

65

75

85

95

Le

ve

l, d

Bu

V/m

1E-2 1E-1 1E0 1E1 1E2 1E3 1E4Frequency, MHz

MAXIMUM VALUESMeasured PEDs

WB Switching Power Supplies

and Video Display Sweeps

NB Local Oscillators

and Clocks

http://upload.wikimedia.org/wikipedia/en/f/ff/Nokia6650_unlocked.jpg

http://en.wikipedia.org/wiki/File:BlackBerry_Bold_9700.jpg


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) trans-

modulation 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


CEM: example of equipment conducted

emission measurement

Power supply switching fondamental & harmonics Microprocessor


CEM: Example of radiated emission measurement


CEM: Example of radiated susceptibility measurement

in RADAR frequency domain on FADEC


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)

Calibration for the Em. FIELD

Testing equipment or System


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 mis-

operating of ECMU under

High voltage & high

magnetic field at low

frequency (50 Hz)


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


ELECTROMAGNETIC PROTECTION:

overview of basic protections

Shielding

Bonding

Grounding

Clamping

Filtering

Segregation

Optical fiber link

Clean and dirty zones design

Balanced Hardening concept

And….


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


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


Example of different filter set-up

Coaxial structure reduce connection inductance


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


Non linear devices basic set for protection in the time domain


Non linear protections: typical value of different devices such as zener

diodes, varistor or gaz spark


Time domain pulses: in order to get a safe design, hypothesis of matching

of source and load resistance is taken (max transmitted energy)


Electromagnetic protection devices: design rules

Protection against time

domain threat:

•LEMP

•NEMP

•ESD

Protection against

frequency domain threat:

•HIRF

•HPM


PROTECTION DEVICES

COMPREHENSIVE & CONSISTENT HARDENING CONCEPT


Appendix

Electromagnetic environment and tests

Information necessary for a technical and

commercial proposal


Technical elements necessary to work out an estimate

Test

Program

Technical

&

Commercial

proposal

System Or

Equipment

Under test

Configurations Furniture's


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


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


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


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


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


CONCLUSION &……. QUESTIONS

Necessity for designing

electromagnetic

protections

in comprehensive &

Consistent manner

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

According to the field

of frequency to be treated

Used tools

for simulation

will not be the same ones

Whatever

computer code has been used

It is necessary to validate

the ideal model

using

large Experimental

simulators


And perhaps for next CISEC conference cycle !!!

20140218 cisec-emc-in-aeronautics

Technology