Download Lightning Protection Guide PDF

TitleLightning Protection Guide
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Total Pages331
Table of Contents
                            Preface
Contents
Signs and symbols
Abbreviations
1. State of the art for the installation of lightningprotection systems
	1.1 Installation standards
	1.2 Work contracts
	1.3 Product standards
2. Characteristics of lightning current
	2.1 Lightning discharge and sequenceof lightning current
	2.2 Peak value of lightning current
	2.3 Steepness of lightning current
	2.4 Charge of lightning current
	2.5 Specific energy
	2.6 Assignment of lightning currentparameters to lightning protectionlevels
3. Designing a lightning protection system
	3.1 Necessity of a lightning protectionsystem – legal regulations
	3.2 Assessment of the risk of damageand selection of protectivecomponents
		3.2.1 Risk management
		3.2.2 Fundamentals of risk assessment
		3.2.3 Frequency of lightning strikes
		3.2.4 Probabilities of damage
		3.2.5 Types of loss and sources of damage
		3.2.6 Loss factor
		3.2.7 Relevant risk components for differentlightning strikes
		3.2.8 Tolerable risk of lightning damage
		3.2.9 Choice of lightning protection measures
		3.2.10 Economic losses / Economic efficiencyof protective measures
		3.2.11 Summary
		3.2.12 Designing aids
	3.3 Inspection and maintenance
		3.3.1 Types of inspection and qualificationof the inspectors
		3.3.2 Inspection measures
		3.3.3 Documentation
		3.3.4 Maintenance
4. Lightning protection system
5. External lightning protection
	5.1 Air-termination systems
		5.1.1 Designing methods and types of airterminationsystems
		5.1.2 Air-termination systems for buildingswith gable roof
		5.1.3 Air-termination systems for flat-roofedstructures
		5.1.4 Air-termination systems on metalroofs
		5.1.5 Principle of an air-termination systemfor structures with thatched roof
		5.1.6 Walkable and trafficable roofs
		5.1.7 Air-termination system for green andflat roofs
		5.1.8 Isolated air-termination systems
		5.1.9 Air-termination system for steeplesand churches
		5.1.10 Air-termination systems for wind turbines(WT)
		5.1.11 Wind load stresses on lightning protectionair-termination rods
	5.2 Down-conductor system
		5.2.1 Determination of the number of downconductors
		5.2.2 Down-conductor system for a non-isolatedlightning protection system
			5.2.2.1 Installation of down-conductor systems
			5.2.2.2 Natural components of a down-conductorsystem
			5.2.2.3 Measuring points
			5.2.2.4 Internal down-conductor systems
			5.2.2.5 Courtyards
		5.2.3 Down conductors of an isolated externallightning protection system
		5.2.4 High voltage-resistant, isolated downconductorsystem – HVI conductor
			5.2.4.1 Installation and performance of theisolated down-conductor system HVI
			5.2.4.2 Installation examples
			5.2.4.3 Project example: Training and residentialbuilding
			5.2.4.4 Separation distance
	5.3 Materials and minimum dimensionsfor air-termination conductorsand down conductors
	5.4 Assembly dimensions for air-terminationand down-conductorsystems
		5.4.1 Change in length of metal wires
		5.4.2 External lightning protection systemfor an industrial structure and a residentialhouse
		5.4.3 Application tips for mounting roofconductors holders
	5.5 Earth-termination systems
		5.5.1 Earth-termination systems in accordancewith IEC 62305-3 (EN 62305-3)
		5.5.2 Earth-termination systems, foundationearth electrodes and foundation earthelectrodes for special structural measures
		5.5.3 Ring earth electrode – Earth electrodeType B
		5.5.4 Earth rod – Earth electrode Type A
		5.5.5 Earth electrodes in rocky ground
		5.5.6 Intermeshing of earth-termination systems
		5.5.7 Corrosion of earth electrodes
			5.5.7.1 Earth-termination systems with particularconsideration of corrosion
			5.5.7.2 Formation of voltaic cells, corrosion
			5.5.7.3 Choice of earth electrode materials
			5.5.7.4 Combination of earth electrodesmade of different materials
			5.5.7.5 Other anticorrosion measures
		5.5.8 Materials and minimum dimensionsfor earth electrodes
	5.6 Electrical isolation of the externallightning protection system– Separation distance
	5.7 Step and touch voltages
		5.7.1 Control of the touch voltage at downconductors of lightning protection systems
6. Internal lightning protection
	6.1 Equipotential bonding for metalinstallations
	6.2 Equipotential bonding for lowvoltage consumer’s installations
	6.3 Equipotential bonding for informationtechnology installations
7. Protection of electrical and electronic systems againstLEMP
	7.1 Lightning protection zones concept
	7.2 LEMP protection management
	7.3 Calculation of the magneticshield attenuation of building/room shielding
	7.4 Equipotential bonding network
	7.5 Equipotential bonding on theboundary of LPZ 0A and LPZ 1
		7.5.1 Equipotential bonding for metalinstallations
		7.5.2 Equipotential bonding for powersupply installations
		7.5.3 Equipotential bonding for informationtechnology installations
	7.6 Equipotential bonding on theboundary of LPZ 0A and LPZ 2
		7.6.1 Equipotential bonding for metalinstallations
		7.6.2 Equipotential bonding for power supplyinstallations
		7.6.3 Equipotential bonding for informationtechnology installations
	7.7 Equipotential bonding on theboundary of LPZ 1 and LPZ 2and higher
		7.7.1 Equipotential bonding for metalinstallations
		7.7.2 Equipotential bonding for power supplyinstallations
		7.7.3 Equipotential bonding for informationtechnology installations
	7.8 Coordination of the protectivemeasures at various LPZ boundaries
		7.8.1 Power supply installations
		7.8.2 IT installations
	7.9 Inspection and maintenance ofthe LEMP protection
8. Selection, installation and assembly of surge protectivedevices (SPDs)
	8.1 Power supply systems (withinthe scope of the lightning protectionzones concept accordingto IEC 62305-4 (EN 62305-4))
		8.1.1 Technical characteristics of SPDs
		8.1.2 Use of SPDs in various systems
		8.1.3 Use of SPDs in TN Systems
		8.1.4 Use of SPDs in TT systems
		8.1.5 Use of SPDs in IT systems
		8.1.6 Rating the lengths of the connectingleads for SPDs
		8.1.7 Rating of the terminal cross-sectionsand the backup protection of surgeprotective devices
	8.2 Information technology systems
		8.2.1 Measuring and control systems
		8.2.2 Technical property management
		8.2.3 Generic cabling systems (EDP networks,TC installations)
		8.2.4 Intrinsically safe circuits
		8.2.5 Special features of the installation ofSPDs
9. Application proposals
	9.1 Surge protection for frequency converters
	9.2 Lightning and surge protection for outdoor lightingsystems
	9.3 Lightning and surge protection for biogas plants
	9.4 Lightning and surge protection retrofitting forsewage plants
	9.5 Lightning and surge protection for cable networks andantennas for TV, sound signals and interactive services
	9.6 Lightning and surge protection in modern agriculture
	9.7 Lightning and surge protection for video surveillancesystems
	9.8 Surge protection for public address systems(PA systems)
	9.9 Surge protection for hazard alert systems
	9.10 Lightning and surge protection for KNX systems
	9.11 Surge protection for Ethernet and Fast Ethernetnetworks
	9.12 Surge protection for M-Bus
	9.13 Surge protection for PROFIBUS FMS, PROFIBUS DP,and PROFIBUS PA
	9.14 Surge protection for telecommunication accesses
	9.15 Lightning and surge protection for intrinsically safecircuits
	9.16 Lightning and surge protection of multi-megawattwind turbines
	9.17 Surge protection for radio transmitter/ receiverstations (mobile radio)
		9.17.1 Power supply230/400 V a.c.
		9.17.2 Fixed networkconnection (ifexisting)
		9.17.3 Radio transmissiontechnology
		9.17.4 Lightning protection, earthing,equipotential bonding
	9.18 Lightning and surge protection for PV systems andsolar power plants
		9.18.1 Lightning and surge protection forphotovoltaic (PV) systems
		9.18.2 Lightning and surge protection forsolar power plants
Literature
DEHN + SÖHNE Brochures
Index
Figures and Tables
Answer Sheet
                        
Document Text Contents
Page 1

LIGHTNING
PROTECTION

GUIDE
2nd updated edition

Page 2

LIGHTNING
PROTECTION

GUIDE
2nd updated edition

Page 165

minals to earth. The impedance of the cable shield
and the shielding terminal creates voltage differ-
ences between shield potential and earth. In such
a case, voltages of up to some kV can develop and
destroy the insulation of conductors or connected
devices. Coarse-meshed shields and the twisting of
the cable shield (pig tail) to the terminal in a rail
clamp are particularly critical. The quality of the
cable shield used affects the number of shield
earthings required. Under certain circumstances,
an earthing is required every 10 metres in order to
achieve an efficient shielding effect. Suitable large
contacting clamps with slipping spring elements
are recommended for the shielding terminal. This
is important to compensate for the yield of the
synthetic insulation of the conductor (Figure
7.3.1.4).

⇒ Maximum length of shielded cables

Cable shields have a so-called coupling resistance
which roughly corresponds to the d.c. resistance
provided by the cable manufacturer. An interfer-
ence pulse flowing through the resistance creates
a potential drop on the cable shield. The permissi-
ble coupling resistance for the cable shield can be
determined as a function of the dielectric strength
of the terminal device and the cable, as well as the
cable length. It is crucial that the potential drop is
less than the insulation strength of the system. If
this is not the case, arresters must be used (Figure
7.3.1.5).

⇒ Extension of LPZs with the help of shielded
cables

IEC 62305-4 (EN 62305-4) states that using a shield-
ed cable between two equal LPZs obviates the
need for arresters. This statement applies to inter-
ferences to be expected from the spatial surround-
ings of the shielded cable (e.g. electromagnetic
fields) and for meshed equipotential bonding con-
forming to the standard. But beware. Depending
on the conditions the installation is set up in, haz-
ards can still arise and make the use of arresters
necessary. Typical potential hazards are: the feed-
ing of the terminal devices from different low volt-
age main distribution boards (MDB), TN-C systems,
high coupling resistances of the cable shields or
insufficient earthing of the shield. Further caution
must be exercised with cables with poor shield cov-
er, which are often used for economic reasons. The
result is residual interferences on the signal lines.
Interferences of this type can be controlled by
using a high-quality shielded cable or surge pro-
tective devices.

7.4 Equipotential bonding network

The main function of the equipotential bonding
network is to prevent hazardous potential drops
between all devices / installations in the inner LPZs,
and to reduce the magnetic field of the lightning.

www.dehn.de164 LIGHTNING PROTECTION GUIDE

RKh = = = 0.4 Ω
Uiso

I
2000 V
5000 A

l = 200 m: RKh = = 2
0.4 Ω

200 m
10-3 Ω

m

U = 2 kVdielectric strength

l = 200 m

I = 5 kA

iso

to be calculated: max. permissible coupling impedance RKh of the cable shielding

shield terminal

cable

cable shield

anchor bar

Fig. 7.3.1.4 Shield connection Fig. 7.3.1.5 Shield connection at both ends – Shielding from capacitive/ inductive coupling

Page 166

The low inductance equipotential bonding net-
work required is achieved by means of intercon-
nections between all metal components aided by
equipotential bonding conductors inside the LPZ
of the building or structure. This creates a three-
dimensional meshed network (Figure 7.4.1). Typi-
cal components of the network are:

⇒ all metal installations (e.g. pipes, boilers),

⇒ reinforcements in the concrete (in floors, walls
and ceilings),

⇒ gratings (e.g. intermediate floors),

⇒ metal staircases, metal doors, metal frames,

⇒ cable ducts,

⇒ ventilation ducts,

⇒ lift rails,

⇒ metal floors,

⇒ supply lines.

Ideally, a lattice structure of the equipotential
bonding network would be around 5 m x 5 m. This
would typically reduce the electromagnetic light-
ning field inside an LPZ by a factor of 2 (correspon-
ding to 6 dB).

Enclosures and racks of electronic devices and sys-
tems should be integrated into the equipotential
bonding network with short connections. This
requires sufficient numbers of equipotential bond-
ing bars and/or ring equipotential bonding bars
(Figure 7.4.2) in the building or structure. The bus-
bars, in turn, must be connected to the equipoten-
tial bonding network (Figure 7.4.3).

Protective conductors (PE) and cable shields of the
data links of electronic devices and systems must
be integrated into the equipotential bonding net-
work in accordance with the instructions of the
system manufacturer. The connections can be
made as a mesh or in the shape of a star (Figure
7.4.4).
When using a star point arrangement S, all metal
components of the electronic system must be suit-
ably insulated against the equipotential bonding
network. A star-shaped arrangement is therefore
usually limited to applications in small, locally con-
fined systems. In such cases, all lines must enter the
building or structure, or a room within the build-
ing or structure, at a single point. The star point
arrangement S must be connected to the equipo-

www.dehn.de LIGHTNING PROTECTION GUIDE 165

Fig. 7.4.1 Equipotential bonding network in a structure or building

Fig. 7.4.2 Ring equipotential bonding bar in a computer facility

Fig. 7.4.3 Connection of the ring equipotential bonding bar with the
equipotential bonding network via fixed earthing point

Page 330

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