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BXT ML4 __ __ _ discharge capacity voltage protection level
BXT ML2 __ __ _ l in kA U in V
10 500
type key 8 400
6 300
4 200
B = Lightning current arrester 2 100
I imp = 2.5 kA (10/350 µs) per core
100 200 300 400 500 600 700 800 100 200 300 400 500 600 700 800
t in µs t in µs
l in kA U in V
10 500
B_ = Combined arrester 8 400
I imp = 2.5 kA (10/350 µs) per core, 6 300
However: Same voltage protection 4 200
level as surge arrester (M) 2 100
100 200 300 400 500 600 700 800 100 200 300 400 500 600 700 800
t in µs t in µs
l in kA U in V
M_ = Surge arrester 10 500
I n = 2.5 kA (8/20 µs) per core 8 400
6 300
4 200
BXT = BLITZDUCTOR XT 2 100
ML4 = Protection module with integrated LifeCheck (ML), four-pole
ML2 = Protection module with integrated LifeCheck (ML), two-pole 100 200 300 400 500 600 700 800 100 200 300 400 500 600 700 800
t in µs t in µs

Figure 8.2.1 SPD classification

Moreover, no detailed knowledge of dimensioning criteria for Protective devices for antenna cables are classified according
arrester backup fuses is required since the backup fuse is al- to their suitability for coaxial, balanced or waveguide cable
ready integrated in and perfectly adapted to the arrester. systems, depending on the physical design of the antenna ca-
ble.
In case of coaxial and waveguide cable systems, the phase
8.2 Information technology systems conductor can be connected directly to the equipotential
bonding system. Earthing sleeves specifically adapted to the
The main function of arresters is to protect downstream termi- relevant cable can be used for this purpose.
nal devices. They also reduce the risk of cable damage.
The selection of arresters depends, among other things, on the Procedure for selecting and installing arresters
following criteria: based on the example of BLITZDUCTOR XT
Opposite to the selection of surge protective devices for power
¨ Lightning protection zones of the place of installation, if any supply systems (see chapter 8.1) where uniform conditions
¨ Energies to be discharged can be expected with respect to the voltage and frequency
¨ Arrangement of the protective devices in 230/400 V systems, the types of signal to be transmitted
in automation and measuring and control systems differ with
¨ Immunity of the terminal devices respect to their
¨ Differential-mode and / or common-mode protection
¨ System requirements, e.g. transmission parameters ¨ Voltage (e.g. 0 – 10 V)
¨ Compliance with product or application-specific standards, ¨ Current (e.g. 0 – 20 mA, 4 – 20 mA)
if required ¨ Type of signal transmission (balanced, unbalanced)
¨ Adaption to environmental / installation conditions ¨ Frequency (DC, LF, HF)

244 LIGHTNING PROTECTION GUIDE www.dehn-international.com