EMI and EMP Protection and Shielding

1/14/2018 2
● Part – I What is EMI, EMP and EMC?
● Part – II Causes / sources of EMI and EMP
● Part – III Effects of EMI and EMP
● Part – IV Mil Stds for EMI / EMP Protection of C4I Facilities
● Part – V Preventive Measures

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What is EMI, EMP and EMC?
Definition

Unwanted Signal and Interference
Definition

 Electromagnetic Pulse - Powerful pulse of short duration
and high intensity electromagnetic radiation such as
lightening or nuclear explosion.
Nuclear Blast
Definition

• Ability of IT Eqpt to operate in proximity of
electromagnetic envmt (EMI&EMP), without causing
or suffering unacceptable degradation in output or
performance
Definition

• 100% electronic shielding and containment.
• No EMI signal can enter inside DC
Definition

No Signals can go outside
Definition

Signals interfere with device / sys
Definition

EMI EMP
EMI is a low intensity
interference
EMP is a high intensity interference
Interfere the electronic /
electrical devices but does not
cause damage
It damages electrical / electronic eqpt
Definition

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Causes / Sources of EMI and EMP?
Definition Causes

Comm / Sig TowersTx LinesMobile PhonesElectronic DevicesThunderstroms
Definition Causes

HV Tx LinesHigh Power
Electronic Devices
Lightning
Nucleur Blast
Definition Causes

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Effects of EMI and EMP?
Definition Causes Effects

• Unaval of Svc (Shut Down)

HACKER
• Stealing of Data – Cyber Attk

 Degrade the performance of IT Devices or cause
malfunctioning – Undesirable response

 Cause elec fire and burning of electronic devices
Nuclear Blast

• Complete Damage to IT Devices causing complete
blackout.

 Degrade the performance of IT Devices or cause
malfunctioning – Undesirable response Comm / Sig Towers

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103 1010
EMI
104 1011
RFI
103 108
EMP
1010
• EMI / RFI - 10KHz to 300GHz
• EMP - 3 KHz – 300 GHz
• NEMP - 1KHz to 100 MHz
• NNEMP - 200MHz to 5GHz

 EMI / RFI - 20 dB (10 times higher than normal lvl)
 EMP - 20-90 dB (10-30000 times higher)
NEMP - 20-90 dB (10-30000 times higher)
NNEMP - 30-60 dB (30-1000 times higher)

 EMI - 20 dB
 RFI - 20 dB
 EMP - 20-90 dB
 NEMP - 20-40 dB or 60-90 dB
 NNEMP - 30-60 dB
 HEMP - 20-40 dB

1/14/2018 26

1/14/2018 27
Mil Stds For EMI / EMP Protection of C4I
Facility
Definition Causes Effects Stds

 MIL-STD-188-125-1 Fixed C4I Facilities
 MIL-STD-188-125-2 Transportable C4I Facilities
 MIL-STD-461 Test equipment for electromagnetic
compatibility
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 Standard for EMP hardening of fixed ground-based
and transportable C4I facilities and prescribed fol:-
 Min performance Req
 Min test req
 Design and test criteria
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Preventive Measures – EMI / EMP
Preventive
Measures

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Faradays Cage
Shielding Cover
Al / Cu / Steel
1
Use Shielded
Power Cable
2
Proper Earthing3
Preventive
Measures

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Option I
Shielding at Device lvl
Not Recom
Option II
Shielding
Enclosures
Recom
Option III
Shielding of Room
Not Recom
Preventive
Measures

 Option 1 : Shielding at component or device Lvl
(individual SW, FW or Chassis etc)
 Pros :
 No need to design Big infra for shielding
 No structural changes req
 Cons :
 Expensive
 Req lot of time for implementation
 Difficult to implement
 Difficult to op and maint
 Concl : Not Recom
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Preventive
Measures

 Option 2 : Shielding Enclosures – Faraday’s cage (at
Row Lvl )
 Pros :
 No need to design Big infra for shielding
 No structural changes req
 Customized solns are aval
 Easy to implement
 Not Expensive
 Cons :
 Racks are req to disassemble
 Req 1 week time to implement
 Cooling may be disturb but
honeycomb vents can compensate
 Concl : Recom
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Preventive
Measures

 Option 3 : Shielding of Room (6 sided shielding
of room )
 Cons :
 Need to design Big infra for shielding
 Structural changes req
 Ceiling changes are req
 Floor changes are req
 Difficult to implement
 Expensive
 Racks are req to disassemble
 Req lot of time to implement
 Concl : Not Recom
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Preventive
Measures

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Lvl 2 : Meet or exceed lvl 1 req
• Surge protection device on power cord, data and comm cables
• Dedicated EMP protected power supply
• Double conversion UPS
• Use fiber optics
• Shielded cable
• Shielded Rack, Room or facility
• EMP filters
•
Lvl 1 :
• Turn off eqpt – unplug power and data / comm lines
• Wrap spare electronic eqpt with aluminum foil
• Dedicated EMP protected backup power supply for 1 week
Preventive
Measures

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Lvl 4 : Meet or exceed lvl 3 req
• Use Military EMP std MIL-STD-188-125-1
• 80+ dB shielding protection
• Double door EMP protected safe entry
• 30+ days of EMP protected power backup
Lvl 3: Meet or exceed lvl 2 req
• Use civ EMP protection std (IEC SC77C)
• 30-80 dB shielding protection through 10GHz
• SPD for eqpt outside shielded area
• Single door EMP safe entry
• 30 days EMP protected power backup
Preventive
Measures

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Signal / telecom Line
Lightening
Arrester
5
2
Surge Protection Device3
Lightening Protection Device4
Preventive
Measures

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Paint Range
Copper conductive EMI shielding appl (>30 MHz)
Silver conductive Higher freq EMI shielding appl
Nickel Conductive Lower freq EMI shielding appl
Graphite conductive ESD prevention appls
Preventive
Measures

 Conductive Paint thickness – 0.025 mm to 0.050 mm
 Pros :
 Easy to use – spray
 Cost effective
 Cons :
 Mostly all conductive paint are designed for plastic casing of
devices.
 Paint can’t block medium and low freq signal.
 Such paint can’t be used for masonry work.
 Paints deteriorate with time – making shielding highly
ineffective.
 It may not be used for more than 3’ x 3’ x 3’ dimension.
 Attenuation lvl is less (<30 dB)
 Concl : Not Recom1/14/2018 40

 EMI Shielding Gaskets – use to avoid gaps and
completely contain the shielding
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Preventive
Measures

 Stainless Steel enclosures
 Fabric Enclosures
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Preventive
Measures

 EMI Shielding Fabric - 35 to 45 dB Protection
with double layer made of strong and
conductive textile
 Ni/Cu/Co Fabric Tape
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Preventive
Measures

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Final Req
Preventive
Measures
Final
Req

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Preventive measure
Faradays cage on double row (HAC) :-
• Material – Copper (preferred steel)
• Cage - 3-6 mm thickness
• 80+ dB shielding protection
• Double door EMP protected entry
Surge protection device at svc entrance – Type 1
Surge protection device at distribution / sub panels – Type 2
Surge protection device at point of use (ferrites) – Type 3
Generator with 30+ days backup must be EMP protected
Double conversion UPS
Shielded cable
Proper grounding
Lightening arrester
Proper cable layout (metal cable tray and tight bundles etc)
Power Line Filters
Data / Signal Line Filters

Preventive
Measures
Final
Req

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EMI and EMP Protection and Shielding

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