Internal LPS.pdf

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© 2002 DEHN + SÖHNE

Internal Lightning Protection

System




The primary source of interference is thelightning electromagnetic impulse (LEMP),

especially the lightning current and itsunattenuated magnetic field, which has the samewave form as the lightning current. The lightning

current can consist of the following strokes:•one first short stroke with positive or negativepolarity

•

subsequent short strokes with negative polarity along stroke with positive or negative polarity.




The susceptible elements are

electric and electronic systems inor at a structure, which have only alimited withstand capability againstimpulse currents and magneticfields.




The withstand capability of such electronicsystems is usually proved by tests in accordancewith IEC 61000-4:

• on conducted impulse currents according toIEC 61000-4-5 with test voltages of 0.5-1-2-4 kV(wave form 1.2/50) and/or with test currents of 0.25-0.5-1-2 kA (wave form 8/20) and

• on magnetic fields according to IEC 61000-4-9with test levels of 100-300-1000 A/m (wave form8/20) or according to IEC 61000-4-10 with test

levels of 10-30-100 A/m (1 MHz).




Potentially SusceptibleEquipment

Interference Immunity According toIEC 61000-4-5 (conducted interference)IEC 61000-4-9 (radiated interference)IEC 61000-4-10 (radiated interference)

SPD

2267e.ppt / 03.05.1999 /2267

LPZ 0

Radiated LightningInterference

LPZ 0

Radiated Interference

H

SPD (LPZ 0 /LPZ 1)

(IEC 61312-3)Induced Lightning

Interference

Line from LPZ 0

SPD (LPZ 1/

(LPZ 2)

(IEC 61312-3)

LPZ 1

LPZ 2

Equipment Shield (housing)

LPZ 2 SPD (LPZ 1/LPZ 2)

(IEC 61312-3)

Conducted

Interference

Potentially SusceptibleEquipment

Interference Immunity According toIEC 61000-4-5 (conducted interference)IEC 61000-4-9 (radiated interference)IEC 61000-4-10 (radiated interference)

Conducted

Interference

Buildings Shield (IEC 61312-2)

Room Shield (IEC 61312-2)

IntegratedSPD

B Con-

ductedInter-ference

Con-

ductedInter-ference

SPD (LPZ 0 /LPZ 1)

IEC 61312-3

Radiated Interference

LPZ 1

H

H

Partial Lightning Current

Line from LPZ 0

B

A

A

LEMP or EMC Situation at a Lightning Strike

Lightning Source of InterferenceLightning Magnetic Field According to IEC 61312-2Lightning Current According to IEC 61312-1




General principle for the division into different LPZ

Electricalpower line

Antenna

Mastor

railing

Waterpipe Telecommunication

line

Equipment

LPZ 2LPZ 1

LPZ 0

Boundaryof LPZ 2

Boundaryof

LPZ 1

Bondinglocation

Bonding of incoming servicesdirectly or by suitable SPD

This Figure shows anexample for dividing astructure into inner LPZs.All metal servicesentering the structure arebonded via bonding barsat the boundary of LPZ 1.In addition, the metalservices entering LPZ 2

(e.g. computer room) arebonded via bonding barsat the boundary of LPZ 2.




LPZ defined byProtection measuresAgainst LEMP(IEC 62305-4)

1 Structure (Shield of LPZ 1) S1 Flash to structure

2 Air-termination system S2 Flash near to the structure

3 Down-conductor system S3 Flash to a service connected to the structure

4 Earth-termination system S4 Flash near a service connected to thestructure

5 Room (Shield of LPZ 2) R Rolling sphere radius

6 Services connected to the

structure

ds Safety distance against too high magnetic field

SPD0A/1

LPZ 2

LPZ 1

SPD1/2

SPD0B /1

SPD0A/1

LPZ 0A

LPZ 0B

6

4

3

5

2

S2

S3

S4

S1

LPZ 0B LPZ 0B

RR

1

ds

ds

6

SPD1/2

Lightning equipotential bonding by means of SPDs

LPZ 0A Direct flash, full lightning current, full magnetic field

LPZ 0B No direct flash, partial lightning or induced current, full magnetic field

LPZ 1 No direct flash, limited lightning or induced current, damped magnetic field

LPZ 2 No direct flash, induced currents, further damped magnetic field

Protected volumes inside LPZ 1 and LPZ 2 must respect safety distances ds




Shield 1

Shield 2

Overhead line

Water pipe Underground

cable

Example for dividing a structure into LPZs with

adequate bonding locationsBonding of incoming servicesdirectly or by suitable SPDs:

SPDs (class I test) required for

services incoming from LPZ 0A

SPDs (class II or III test)required otherwise

Bonding network




0A /1

0B /1

1/2

1/2

LPZ 0A Direct flashes, full lightning currentLPZ 0B No direct flashes, partial lightning or induced currentLPZ 1 No direct flashes, partial lightning or induced currentLPZ 2 No direct flashes, induce currents, further damped magnetic field

Protected volume inside LPZ 1 and LPZ 2 must respect separation distance ds

LPZ relevant to protection against failures of

electrical and electronic systems (IEC 62305-4)




Protection to reduce the failure of internal

systems (1)Protection against LEMP to reduce the risk of failureProtection against LEMP to reduce the risk of failureof internal systems shall limit :of internal systems shall limit :

OOvervoltages due to lightning flashes to the structurevervoltages due to lightning flashes to the structureresulting from resistive and inductive coupling ;resulting from resistive and inductive coupling ;

OOvervoltages due to lightning flashes near thevervoltages due to lightning flashes near the

structure resulting from inductive coupling ;structure resulting from inductive coupling ;OOvervoltages transmitted by lines connected to thevervoltages transmitted by lines connected to thestructure due to flashes to or near the lines ;structure due to flashes to or near the lines ;

MM

agnetic field directly coupling with internal systems.agnetic field directly coupling with internal systems.




Protection to reduce the failure of internalsystems (2)

System to be protected inside a LPZ 1 or higherSystem to be protected inside a LPZ 1 or higher ::

magnetic shields to attenuate the inducing magnetic fieldmagnetic shields to attenuate the inducing magnetic field

suitable routing of wiring to reduce the induction loopsuitable routing of wiring to reduce the induction loop

Bonding at the boundaries of LPZ for metal parts andBonding at the boundaries of LPZ for metal parts and

systemssystemscrossing the boundaries (bonding conductors +crossing the boundaries (bonding conductors +

SPDs)SPDs)Coordinated SPD protectionCoordinated SPD protection (overvoltages < rated impulse(overvoltages < rated impulse

withstand voltage)withstand voltage)




Design of an LPMSI0, H0

Partiallightningcurrent

LPS +Shield LPZ 1

Apparatus(victim)

HousingU1 , I1

LPZ 0

LPZ 2

LPZ 1

SPD 1/2 SPD 0/1

U2 , I2 U0 , I0

H2

H1

H0

Shield LPZ 2LPMS using spatial shields

and coordinated SPD protection.Apparatus well protected againstconducted surges (U2<< U0 I2 << I0) as well as

against radiated magnetic fields (H2 << H0)

I0, H0


LPS +Shield LPZ 1

Apparatus(victim)

HousingU1 , I1

LPZ 0

LPZ 1

SPD 0/1

U0 , I0

H1

H0

LPMS using spatial shield of LPZ 1and SPD protection at entry of LPZ 1.Apparatus protected against

conducted surges (U1 < U0 I1 < I0) as well asagainst radiated magnetic fields (H1 < H0)




Design of an LPMS

LPMS using internal line shieldingand SPD protection at entry of LPZ 1.Apparatus protected againstconducted surges (U2 < U0 I2 < I0) as

well as against radiated magneticfields(H2 < H0)

I0, H0


LPS (No shielding)

Apparatus(victim)

HousingU2 , I2

LPZ 0

LPZ 1

SPD 0/1

U0 , I0

H0

H0

LPMS using coordinated SPD protection.Apparatus protected against conductedsurges (U2 << U0 I2 << I0 ) but notagainst radiated magnetic fields(H0)

I0, H0


LPS (No shielding)

Apparatus(victim)

Shielded housingor chassis etc.

U2 , I2

LPZ 0

LPZ 1

SPD 0/1/2

U0 , I0

H0

H2H2LPZ 2

SPD SPD 1/2

U1 , I1




(Potentially Susceptible Equipment)

i0 and H0 impulse 10/350 µs and impulse 0,25/100 µsIEC 61000-4-5: u: impulse 1,2/50 µs, i: impulse 8/20 µsIEC 61000-4-9: H: impulse 8/20 µs (damped oscillation 25 kHz), TP = 10 µsIEC 61000-4-10: H: damped oscillation 1 MHz (impulse 0,2/0,4 µs), TP = 0,25 µs

Device Shield

Building Shield

Room Shield

Internes SPD SPD SPD

Lightning Current i0 and

Magnetic Field H0

Primary Source of

Interference

H2H1

H0

u2 •i2 Partial Lightning

Current

LPZ 1LPZ 1LPZ 1

LPZ 0LPZ 0LPZ 0

LPZ 2LPZ 2LPZ 2

Immunity defined in :IEC 61000-4-5 (conducted interferences)IEC 61000-4-9and 61000-4-10

(radiated

interferences)}

u1 •i1

}

Information Technology Device

LPZ 3LPZ 3LPZ 3

EMC-SITUATION AT A LIGHTNING STRIKE

30.10.02 / S1769




EMC-Immunity of electronic systems

according to IEC 61000-4

04.11.02 / 3402_OB

Immunity Against Magnetic FieldIEC 61000-

IEC 61000-4-10

Conducted Impulse Currents

IEC 61000-4-10

ImmunityLevel

4

32

1

Surge Voltage1,2/50 µs

(kV)

Surge Current8/20 µs

(kA)

4

21

0,5

2

10,5

0,25

Severityof Test

5

43

Test Level8/20 µs

(first partial lightning)(A/m)

1000

300100

Test Level1 MHz

(subsequent

stroke)(A/m)

100

3010




Test Levels

EN 61000-4-10:1993 + A1:2001, Annex C

04.11.02 / 3402

Class 3: Protected Environment The environment is characterized by the vicinity of protective earth connectionsfor the lightning protection installations and metal structures.Commercial and buisiness areas, control buildings, structures and areas which are notpart of heavy industry, where, however, lightning protection installations or metalstructures are in direct vicinity. Computer rooms of power switching stations can beconsidered as representative for this environment.

Class 4: Typical Industrial Environement

The environment is characterized by protective earth connections for lightningprotection installations and metal structures.Structures of heavy industry and power supply systems as well as control roomsof power switching stations can be considered as representative for this environment.

Class 5: Environment With a Lot of Industry The environment is charcterized by the following:Circuits, power rails, ormedium and high voltage lines with several ten kA;Protective earth connections for lightning protection installations or for highstructuressuch as pylons conducting the whole lightning current.




IEC 62305-4 illustrates the coupling mechanismand shows that it can be influenced appropriatelyby earthing, equipotential bonding, spatial

shielding and line shielding and routing of metalconductors.

According to the Lightning Protection ZonesConcept the zone to be protected is divided intoLightning Protection Zones (LPZ) in order to adapt

zones of different LEMP risk levels to thewithstand capability of the electronic system.




According to this flexible concept, suitable LPZcan be defined upon quantity, kind and sensitivityof the electronic equipment. From small local

zones (to individual enclosures) up to greatintegral zones comprising the complete volume of the building.




Outer Zones

•LPZ 0A – Threat by direct lighting strikes, fromimpulse currents up to the complete lightningcurrent and the complete field of lightning

•LPZ 0B – Protected against direct lightningstrikes, threat by impulse currents up to partiallightning currents and the complete field of

lightning




Inner Zones (Protected against Direct LightningStrikes)

•LPZ 1 – Impulse currents limited by currentsharing and by Surge Protective Devices (SPDs)at the LPZ boundaries. The field of lightning canbe attenuated by spatial shielding.

•LPZ 2 ... n – Impulse currents further limited bycurrent sharing and by SPDs. Lightning fieldusually attenuated by spatial shielding




The field of lightning is mostly attenuated byspatial shielding. The requirements on the inner

zones have to be defined in accordance with thewithstand capability of the electrical andelectronic equipment to be protected.

At the boundary of each inner zone theequipotential bonding has to be effected for allentering metal parts and services (directly or by

suitable SPDs) and a spatial shielding can beinstalled.




Basic protection measures in an LPMSBasic protection measures in an LPMS

1) earthing and bonding :

earth-termination system + bonding network

ex : each conductive service incoming to the structure shall be bondeddirectly or via suitable SPD at the entrance point.

2) magnetic shielding and line routing :- grid-like spatial shielding

- shielding of internal lines (shielded cables, cable ducts,...)- shielding of external lines entering the structure

- line routing of internal lines(avoiding induction loops and reducing internal surges)

3) surge protective device system (SPD system) :

limiting both external and internal surges(coordinated set of SPDs)




LPMS management plan for new buildingsand for extensive changes in construction or use of buildings

Step Aim Action to be taken by

Initial riskanalysis1)

Checking the need for LEMP protection.

If needed, selection of a suitable LPMS using therisk assessment method.

- Lightning protection expert2)

- owner

Final risk

analysis

1)

The cost/benefit relation for the selectedprotection measures should be optimized usingagain the risk assessment method.As result are defined:

- LPL and the lightning parameters

- LPZ and their boundaries

- Lightning protection expert2)

- owner

LPMS planning Definition of an LPMS:

- spatial shielding measures

- bonding networks

- earth termination systems

- line shielding and routing

- shielding of incoming services- coordinated SPD protection

- Lightning protection expert

- owner

- architect

- planners of internal systems

- planners of relevant installations

LPMS design General drawings and descriptions

Preparation of lists for tendersDetailed drawings and time tables for theinstallation

- Engineering office or equivalent

1) See IEC 62305-2.2) With a broad knowledge of EMC and knowledge of installation practices.




LPMS management plan for new buildings and for

extensive changes in construction or use of buildingsStep Aim Action to be taken by

Installation of the

LPMSprotection systemincluding su-pervision

Quality of installation

Documentation

Possibly revision of the detailed drawings

- Lightning protection expert

- installer of the LPMS- engineering office

- supervisor

Approval of the

LPMSprotection system

Checking and documentation of the state of the

system

- Independent lightning protection

expert- supervisor

Recurrentinspections

Ensuring the adequacy of the LPMS - Lightning protection expert

- supervisor

1) See IEC 62305-2.2) With a broad knowledge of EMC and knowledge of installation practices.




Metal component on the roof

Extraneous metal services

Telecom lines

0.4 kV power line

20 kV power line

Bonding

terminals

Shieldedcabinet

Interception meshEquipment

on the roof

Metal facade

Camera

Steel reinforcementin concrete

Steel reinforcementSensitiveelectronicequipment

ExtendedLPZ 0A

Ground level

Metal cable conduit(extended LPZ 0A)

Foundation earthingelectrode

Car parking

• equipotential bonding

surge protective device (SPD)

Example of anLPMS

for an officebuilding




All entering metal services are to be bondedat the boundary of LPZ 1.




Moreover, the standard also shows how toreduce the expenditure for equipotential

bonding by means of a connection of severalLPZ or an expansion of one LPZ.



© 2002 DEHN + SÖHNE 07.11.02 / 3404_a

100%External Lightning Protection

LPZ 0 LPZ 0

LPZ 1 LPZ 1

SPDSPD

EBB EBB

I1

I2

LPZ = Lightning Protection ZoneSPD = Surge Protective Device

(Class I - Test, Lightning Current Arrester)

EBB = Equipotential Bonding Bar I1, I2 = Distribution of Lightning Current

I

I2

Conductors Between Buildings



© 2002 DEHN + SÖHNE 07.11.02 / 3404_b

100%

External Lightning ProtectionLPZ 0 LPZ 0

LPZ 1 LPZ 1

SPDSPD

EBB EBB

I1 I2

I2

LPZ = Lightning Protection ZoneSPD = Surge Protective Device

(Class II - Test, Surge Arrester)

EBB = Equipotential Bonding Bar I1, I2 = Distribution of Lightning Current

LPZ 2 Lightning current conductivecable shield, shielded cableduct, ...In the cable /cable duct LPZ 1

I

LPZ 2LPZ 1

Shielded Conductors Between Buildings




Equipotential bonding measures have to minimise

potential differences among conductive parts of the structure or of the electronic system. This canbe achieved by means of a bonding network and

the equipotential bonding for all metal parts andservices at the LPZ boundaries (directly or viaSPDs).




Example for dividing a structure into several

LPZs and adequate bonding

1540e_b 1540e.ppt / 18.11.99 / ESC

LPZ 0ALPZ 0A

LPZ 2LPZ 2

e.g. Computer Room

LPZ 0BLPZ 0B ExternalLightningProtection

Bonding Bar 1at theBoundary of LPZ 0A, 0B andLPZ 1

LPZ 1LPZ 1

Cables, Lines

Local Bonding Bar 2 at the Boundaryof LPZ 1 and LPZ 2

Bonding of Shield 2

Room,Representing Shield 2

Structure Representing Shield 1

Earth TerminationSystem




Integration of electronic systems into the bonding netword

Star configurationS

Meshedconfiguration

S

Basicconfiguration

Integrationinto bonding

network

Bonding network

Bonding conductor

Equipment

Bonding point to thebonding network

Earthing Reference Point

Star point configurationintegrated by starpoint

Meshed configurationintegrated by mesh

ERP

SS

MM




The star configuration requires all metalcomponents of the electronic system to beinsulated against the bonding network. It may be

connected with the bonding network at oneearthing reference point only (entry). It is mostlyused for small, locally limited systems.




For the meshed configuration the metalcomponents do not have to be insulated, but aremultiply connected with the bonding network.

This configuration is used for broad and opensystems with many lines and several entries.




Bonding of lightning protection zones with meshed and star-shaped

functional equipotential bonding at a complex zone structure

1076e.ppt / 18.11.99 / ESC1076e

Protection ZoneShield

LPZ: LightningProtection Zones

Device

Electric Insulation

LPZ 1a

Protection ZoneShield

Central

EquipotentialBonding Point

LPZ 1a

LPZ n

LPZ 1

LPZ m



© 2002 DEHN + SÖHNES659_b

energie-technischesNetz

üü

Room Shield

M

LPZ 1LPZ 1LPZ 1

LPZ 1LPZ 1LPZ 1

LPZ 0 ALPZ 0LPZ 0 AA

LPZ 0 ALPZ 0LPZ 0 AA

LPZ 3LPZ 3LPZ 3

SEMPSEMP

LEMPLEMP

LEMPLEMP

LEMPLEMP

LPZ 0 BLPZ 0LPZ 0 BB

LPZ 0 BLPZ 0LPZ 0 BBLPZ 0 BLPZ 0LPZ 0 BB

üü üü

üü üü

üü

üü

SPD class I (Lightningcurrent arrester)

üüSPD class II or class III(Surge arrester)

üü üü

LPZ 2LPZ 2LPZ 2

LPZ 2LPZ 2LPZ 2

659 / 10.09.01/ OB

Information

Techn. Network

Air Ventilation

Power SupplySystem

Terminal Unit

Building with extended EDP-Systems Lightning protection zones

(LPZs 0 A, 0B, 1, 2 and 3) and bonding at the zone-interfaces

Structure Shield

Ring EBB

Steel Reinforcement

üü üü

Documents

Internal LPS.pdf