2. HERF
• Fuel fire due to accidental ignition
• Due to arcs caused by RF energy
• In presence of flammable fuel-air vapours
• Probability of ignition of fuel vapours by RF-induced
arcs
• Is small
• Highest during fueling
• Conditions to be met for ignition
• Flammable Fuel-Air Mixture must be present
• Arc must have sufficient energy to cause ignition
• Arc Gap ≥ 0.5 mm
4. HERF
• Basis of limits: To ignite gasoline in an explosive vapour
test device
• Volt-Ampere product of 50 or more required
• Limits
• ≥ 225 MHz: Avoid illuminating fuel-handling areas with a peak
power density of 5 W/cm2 or more
• ≤ 225 MHz:
• Antennas radiating 250 watts or less shall be installed no less than 50
feet from fueling operations/fuel-handling areas
• Antennas radiating more than 250 watts shall be separated from
fueling/fuel-handling areas such that the power density in the fueling
area is no greater than would exist at 50 feet from an antenna
radiating 250 watts (0.009 mW/cm2).
• Transmitters with power 10 W or less: Don’t allow within 10 ft of
fuel handling area
5. HERF
LSHSD / JP5 (AVCAT) MOGAS / AVGAS / JP4
Probability of ignition due
to RF energy induced arcs
REMOTE
Probability of ignition due
to RF energy induced arcs
is COMPARATIVELY HIGHER
Vapor pressures are low
enough that, under ordinary
temperatures, there is virtually
no chance of fire from an RF-
induced arc
6. Ship board Fueling Precautions
• Do not energize any transmitter (radar or
communications) on the aircraft or motor vehicle
being fueled or on adjacent aircraft or motor vehicles.
• Do not make or break any electrical, static ground
wire, tie-down connection, or any other metallic
connection to the aircraft or motor vehicle while it is
being fueled. Make the connections before fueling
commences; break them afterwards.
• Turn off all Radars directly illuminating Fueling Areas
• Do not energise HF transmitting Antennas within the
Quadrant of ship where fueling is being done
9. Ionizing Radiations
• Capable of removing
electrons from atoms
• Examples: α, β, γ,
neutron & X-rays
• Can cause molecular
changes leading to
tissue damage
• In high doses, can result
in mutation, radiation
sickness, cancer, and
death
Incoming
Photon
Ejected
Electron
10. Non-ionizing Radiations
• Don’t have sufficient
energy to dislodge
electrons
• Can only excite electrons
• Energy not sufficient to
disrupt chemical bonds
• Examples: LF, RF,
Microwaves, Visible
Light, Infra Red
• Cause heating in body
tissue
11. Boundary between Ionising & Non-ionising Radiations
• 13.6eV or
• wavelength of approximately 0.1 micron
• situated in the far ultraviolet region
12. How do Non-ionizing Radiations affect Humans ?
• Cause
• body tissue to heat
• electrical currents to
flow in the semi-
conducting material
of exposed human
flesh
• Shocks & Burns
• Two types of effects
• Thermal
• Non-thermal
13. Thermal Effect of EMR on Human Body
• Conversion of EM energy into heat
• Mechanical collisions between tissue molecules moving
due to excitation by EM waves
• Re-radiation by excited molecules (small antennas)
• EM energy travels more deep
• Cells die at about 107 °C
• Body’s response
• Body constantly replaces dead cells
• Blood flow & sweating normalises temperature
• Damage depends on
• Rate at which cells die / are replaced
• Which cells die
14. Factors affecting Thermal Effect of EMR
Duration of Exposure
• More time = more heat
• Standard 6 min / 30 min avg times
Power of EM field • More power = more heat
Wavelength of EM wave
• Average Man = 70-85 MHz
• Average Woman = 80-100 MHz
• New born infant = 300 MHz
• Big built Man = 30 MHz
• Below 1 GHz = Deep penetration
• Above 3 GHz = Surface heating
Polarization of EM wave • Body orientation w.r.t. field matters
Body part
• Eyes & Testes more vulnerable since less
blood supply
Dissipation of heat
• Environmental air circulation rate
• Clothing
• Blood circulation & sweating
15. Specific Absorption Rate (SAR)
• Incremental EM Power (dP) absorbed by an
incremental Mass (dm)
dV
dP
dm
dP
SAR
• Amount of energy, absorbed over an exposure
time period, divided by the total mass of the body
Unit: Watts per Kilogram (W/Kg) or milli watts
per gram (mW/g)
16. Permissible Exposure Limits (PEL)
Maximum Permissible Exposure (MPE)
• Standards
• IEEE C95.1-2006
• ICNIRP (International Commission on Non- Ionizing
Radiation Protection) Guidelines, 1998 and reviewed in
2009
• Two sets of PEL/MPE limits
• Controlled (Occupational) exposure
• Uncontrolled (General Population i.e. public) exposure
• Other standards
• US Navy’s NAVSEA OP 3565 VOL1
• NATO’s STANAG 2345E
17. Permissible Limits : Controlled Exposure
For whole body exposures and overall SAR of 0.4 W/Kg averaged over 6 minutes
For Far field, use Power Density values
For Near field, use E and H Field Strength Limit values
Maximum exposure Levels NOT to exceed 100 KV/m
19. Measurement
• EM Fields
• Broadband meters
• Electric field probes
• Magnetic field probes
• Shaped frequency probes
• Measure
• no closer than
• 5 cm from the radiating
device
• 20 cm from a re-radiating
structure
20. Measurement
• Contact currents
• Instruments that can
simulate impedance of
human body
• Instruments having
averaging time less than
1s
• RF Burn
• RF Burn Gun
• Personal Dosimeters
23. Parts of EID / EED
• Bridgewire
• Thin resistive element
• Material
• Nichrome; Gold; Platinum; Silver; Tungsten
• Electrical Energy -> Heat / Light / Shock
• Header / Contacts / Leads
• Primary Initiator / Explosive
24. Hazard due to EMR
• EMR hazard is the result of
• absorption of EM energy by the firing circuitry of EID’s
• By exposure to RF environments, EID's may be
• accidentally initiated or
• their performance degraded
25. Two potential forms of
Unintentional / Premature RF-induced EID response
• Activation of EID
• by EM energy coupled directly into the device or
• upset of an energized firing circuit, resulting in a firing signal erroneously sent
to the EID
• Degradation or dudding of EID
• by EM energy coupled directly into the device
26. Negative Consequences
• Activation
• SAFETY
• premature initiation of explosive trains
• RELIABILITY
• once initiated, EID’s can no longer perform their intended function, thus rendering the
system incapable of performing its mission
• Degradation / Dudding
• RELIABILITY
• presence of EM energy in an EID can alter its ignition properties without actually firing
the device, so the device will not function when legitimate firing stimuli are applied
27. Decibel
• convenient way of expressing ratios of quantities
• power ratio, P2:P1, in dB is
• Example
• comparing a 10-watt received power to a 5-watt
specification
• received power exceeds the specification by
29. Decibel
• can also be used to express ratios of power densities
or electromagnetic field intensities
• Example
• If incident electric field intensity is 3 V/m and reflected field
intensity is 1 V/m
• ratio of incident to reflected field intensities is
30. Decibel
• Normally used for antenna or amplifier gains, cable or
filter losses
• Examples
• an amplifier that receives a 1-watt signal and produces a
100-watt signal has a gain of
• a cable whose input signal has an amplitude of 3.0 volts
and whose output signal has an amplitude of 2.8 volts
exhibits a gain of
31. Decibel
• Signal amplitudes can also be expressed in decibels
• as a ratio of the amplitude to a specified reference
• Example
• a 100-μvolt signal amplitude can be expressed as
32. dBm
• dBm is same as dB(mW)
• Absolute power unit as against relative dB
• 0 dBm
• 1 mW
• 10 dBm
• 10 mW
• 20 dBm
• 100 mW
• 30 dBm
• 1000 mW = (10)3 mW = 1 W
• -30 dBm
• (10)-3 mW = 1 μW
• Used to define power output, sensitivity etc
33. Conducted Voltage
30
dBW
dBm P
P
R
V
P
2
EMI community uses voltage as the basic conducted measurement
reference unit which is measured by an EMI receiver
V = circuit voltage in volts to be measured
R = circuit impedance in ohms across which V is measured
P = power in watts
50
for
107
90
log
10
R
P
V
R
P
V
dBm
V
dB
dBm
V
dB
35. Conducted Current
in
out
T
I
V
Z
EMI community also uses current as the basic conducted measurement
reference unit which is measured by a current probe
ZT = transfer impedance of the current probe
Vout = output voltage across current probe when terminated in 50 Ω EMI
receiver
Iin = unknown input current flow in wire around which probe is snapped
dB
V
dB
A
dB Z
V
I
Manufacturer of current probe furnishes ZdBΩ as the transducer
calibration factors
37. Near & Far Fields
H
E
PD
Power density of EM field measured in units of watts/m2 is
PD = power density in W/m2
E= electric field intensity in V/m
H = magnetic field intensity in A/m
Z = 120π = 377 Ω for far field conditions. Thus electric & magnetic fields
are uniquely related in the far field but such a unique relation does not
exist in the near field
The electric & magnetic field intensities are related by the wave
impedance, Z in ohms
H
E
Z
38. Radiated Electric Field
H
E
PD
Z
E
PD
2
EMI community uses electric field intensity as against power density as
the basic radiated measurement reference unit which is measured by an
antenna & EMI receiver
E = electric field intensity in V/m to be measured
Z = wave impedance in ohms at the point where E is measured
PD = power density in watts/m2 at the point of measurement
377
for
116
90
log
10
2
2
/
/
/
/
Z
P
E
Z
P
E
m
dBm
m
V
dB
m
dBm
m
V
dB
40. Radiated Magnetic Field
Z
E
H
H = Magnetic field intensity in A/m
E = Electric field intensity in V/m
Z = Wave impedance in Ω
377
for
52
log
20
/
/
/
/
Z
E
H
Z
E
H
m
V
dB
m
A
dB
m
V
dB
m
A
dB
41. Radiated Magnetic Field
H
B
EMI community uses magnetic flux density, B in its specifications rather
than magnetic field intensity, H
B = magnetic flux density in Tesla
H = magnetic field intensity in A/m
μ = absolute permeability of medium in henrys/m
μ = 4π x 10-7 h/m for air
1 Tesla = 1 weber/m2 = 104 gauss
160
377
for
190
2
/
/
dBgauss
dBpT
m
V
dB
dBpT
m
A
dB
dBpT
B
B
Z
E
B
H
B
47. International Level EMC Standards
Organisations
• ITU (International Telecommunications Union)
• UN agency
• Allocation of RF spectrum
• Registration of RF assignments
• IEC (International Electrotechnical Commission)
• UN agency
• Preparation & publishing of international standards
48. International Level EMC Standards
• CISPR (Comite International Special des Perturbations
Radioelectriques) (International Special Committee on Radio
Interference)
• Special committee under sponsorship of IEC
• Areas of work
• Protection of radio reception from disturbance sources like electrical appliances of all
types, the electricity supply system, industrial, scientific and electromedical RF,
broadcasting receivers (sound and TV) and, increasingly, IT equipment (ITE)
• Equipment, methods & limits of disturbance measurement
• Immunity limits
49. IEC Immunity Specifications
• IEC 801-2, Immunity to Electrostatic Discharge
• IEC 1000-4-2:1995
• IEC 61000-4-2:1995
• IEC 801-3, Immunity to Radiated Electromagnetic Fields
• IEC 1000-4-3:1995
• IEC 61000-4-3:1995
• IEC 801-4, Immunity to Electrical Fast Transients
• IEC 1000-4-4:1995
• IEC 61000-4-4
• IEC 801-5, Surge immunity requirements
• IEC 801-6, Immunity to conducted disturbances induced by
radio frequency fields
50. European Committee EMC Standards
• EC Directive on EMC
• 89/336/EEC dated 23 May 1989
• Towards a single market economy
• Technical details of tests, emission limits, levels for immunity contained in
European Norms (EN)
• Contains only legal requirements
• EMC standards published separately
• CE conformity mark to denote compliance
51. European Community EMC Standards
• CENELEC EURONORMS
• Prepared by CENELEC Technical Committee
• Comité Européan de Normalisation Electrotechnique
• European Committee for Electrotechnical Standardization
• Based on work of IEC/CISPR
• CISPR number retained
• EN 55022 same as CISPR 22
• Comprise of Basic, Generic, Product & Product Family standards
52. US EMC Standards
• Voluntary EMC Committees coordinated by ANSI (American National
Standards Institute)
• IEEE EMC Society
• Worldwide membership
• Accredited Standards Committee C63
• Provides international technical coordination with CISPR as the US National committee
to the IEC
• Publications developed in cooperation with FCC
• Society of Automotive Engineers Committee AE-4
• Formed to work on EMC issues with aircraft engineers
53. RTCA & EUROCAE Standards
• For EMC of Commercial Aircraft
• RTCA (Radio Technical Commission for Aeronautics) in US
• DO-160C
• EUROCAE (European Organisation for Civil Aviation Electronics)
• ED-14C
• Very similar to MIL-STD-461, Def Stan 59-41 (Part 3), STANAG
3516(AE)
54. Sample National Level Organisations
ITE Radio Appliance Medical
USA FCC FCC FCC exempt FDA/CDRH
Russia GOST Glavgossvyaznadzor GOST Roszdravnadzor
Japan VCCI MIC METI MHLW
China CNCA CNCA CNCA SFDA, MOH
CDRH: Center for Devices and Radiological Health
GOST: Gosstandart (State Committee for Quality Control and Standardization)
Glavgossvyaznadzor: Main Inspectorate in Communications
Roszdravnadzor : Federal Service for Control over Healthcare and Social Development
VCCI: Voluntary Control Council for Interference by Information Technology Equipment
MIC: Ministry of Internal Affairs and Communications
METI: Ministry of Economy, Trade and Industry
MHLW: Ministry of Health, Labor and Welfare
CNCA: Certification and Accreditation Administration of the PRC
SFDA: State Food and Drug Administration
63. 63
Applies To Equipment and Subsystems
Conducted and Radiated Emissions,
Susceptibility (CE, CS, RE, RS)
Requirements, and Test Procedures
Requirements Tailored to Equipment
Characteristics and Installation
461E
64. EMC
Immunity
Emission
E M C
Electromagnetic Compatibility
Susceptibility
E M S
Conducted
Emission (CE)
Radiated
Emission (RE)
Conducted
Susceptibility
(CS)
Radiated
Susceptibility
(RS)
Emission
E M I
65. Requirement Description
CE101 Conducted Emissions, Power Leads, 30 Hz to 10 kHz
CE102 Conducted Emissions, Power Leads, 10 kHz to 10 MHz
CE106 Conducted Emissions, Antenna Terminal, 10 kHz to 40 GHz
CS101 Conducted Susceptibility, Power Leads, 30 Hz to 150 kHz
CS103 Conducted Susceptibility, Antenna Port, Intermodulation, 15 kHz to 10 GHz
CS104 Conducted Susceptibility, Antenna Port, Rejection of Undesired Signals, 30 Hz to 20 GHz
CS105 Conducted Susceptibility, Antenna Port, Cross-Modulation, 30 Hz to 20 GHz
CS109 Conducted Susceptibility, Structure Current, 60 Hz to 100 kHz
CS114 Conducted Susceptibility, Bulk Cable Injection, 10 kHz to 200 MHz
CS115 Conducted Susceptibility, Bulk Cable Injection, Impulse Excitation
CS116 Conducted Susceptibility, Damped Sinusoidal Transients, Cables and Power Leads, 10 kHz
to 100 MHz
RE101 Radiated Emissions, Magnetic Field, 30 Hz to 100 kHz
RE102 Radiated Emissions, Electric Field, 10 kHz to 18 GHz
RE103 Radiated Emissions, Antenna Spurious and Harmonic Outputs, 10 kHz to 40 GHz
RS101 Radiated Susceptibility, Magnetic Field, 30 Hz to 100 kHz
RS103 Radiated Susceptibility, Electric Field, 2 MHz to 40 GHz
RS105 Radiated Susceptibility, Transient Electromagnetic Field 65
66. Equipment and Subsystems
Installed In, On, or launched
from the following platforms
or Installations
Requirement Applicability
CE101
CE102
CE106
CS101
CS103
CS104
CS105
CS109
CS114
CS115
CS116
RE101
RE102
RE103
RS101
RS103
RS105
Surface Ships A L A S S S A L A A A L A A L
Submarines A A L A S S S L A L A A A L A A L
Aircraft, Army, Including Flight Line A A L A S S S A A A A A L A A L
Aircraft, Navy L A L A S S S A A A L A L L A L
Aircraft, Air Force A L A S S S A A A A L A
Space Systems, Including Launch
Vehicles
A L A S S S A A A A L A
Ground, Army A L A S S S A A A A L L A
Ground, Navy A L A S S S A A A A L A A L
Ground, Air Force A L A S S S A A A A L A
Legend:
A L
S
Applicable Limited as specified in the individual sections of this standard
Procuring activity must specify in procurement documentation Requirement is not applicable.
66
67. 1 to 4 m
antenna mast
Groundplane
EUT
direct
reflected
turntable
shielding
73. Labs undertaking EMC Tests in India
• SAMEER – Centre for Electromagnetics
• Chennai
• Mumbai
• Kolkata
• RCI, Hyderabad
• LRDE, Bangalore
• BEL, Bangalore
• DLRL, Hyderabad
• STQC
• ERTL (Delhi, Kolkata, Mumbai, Trivandrum)
• ETDC (10 locations)
• CETE (5 locations)
• Individual companies
74.
75. • Car is disabled and engine controller damaged by keying a HAM radio
transmitter installed in the trunk
• Can’t receive favorite FM radio when the headlights are on
• Can “hear” windshield wipers in the car radio
• Engine misfires when driving under a high-voltage power line
• Lightning strike causes cruise control to engage and accelerate the
vehicle
• Electrostatic discharge while inserting the ignition key damages
ignition circuitry
