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In addition to power supply lines, telecommunication lines are Risks
the most important lines. Permanently functioning interfaces Copper cables with a low shielding effect are used as con-
to the “outside world” are vital for the highly technical pro- necting cables to the local exchange and in a company’s
cesses in today’s industrial plants and offices. internal cabling system. High potential differences can oc-
Telecommunication line networks frequently extend over some cur between the building installation and the incoming lines
2
km . Therefore, it is quite likely that surges are injected into since the incoming lines extend beyond several buildings.
such widespread networks. Potential rise of the cores caused by galvanic and inductive
The safest solution to protect a structure from the negative coupling must be expected. If high-power and low-power
consequences of lightning effects is to install a complete light- lines are routed in parallel, switching overvoltages in the
ning protection system consisting of an external and internal power system can also cause failure which interferes with
lightning protection system. the low-power lines.

fixed-line customer Ethernet 10 MBit Type Part No.
provider or ATM 25 BXT ML2 BD 180 920 247
+ BXT BAS + 920 300
SDB
DRL 10 B 180 FSD 907 401
+ EF 10 DRL + 907 498
+ DRL PD 180 + 907 430
BCU 2) DPRO 230 NT 909 310
230 V~
PC DPRO 230 LAN100 909 321
ADSL RJ 45
modem DLI TC 2 I 929 028
DSM TC 2 SK 924 272
DG M TNS 275 952 400
NT 1) splitter analogue
telephone 1) Network Termination
2) Broadband Connection Unit
Figure 9.14.1 Lightning and surge protection for an analogue connection with ADSL

fixed-line customer Ethernet 10 MBit Type Part No.
provider or ATM 25 BXT ML2 BD 180 920 247
+ BXT BAS + 920 300
SDB
DRL 10 B 180 FSD 907 401
+ EF 10 DRL + 907 498
+ DRL PD 180 + 907 430
BCU 2) DPRO 230 NT 909 310
230 V~
PC DPRO 230 LAN100 909 321
RJ 45
ADSL DPRO 230 ISDN 909 320
modem
RJ 45 DLI ISDN I 929 024
DSM ISDN SK 924 270
S 0
DG M TNS 275 952 400
NT 1) splitter NTBA ISDN 1) Network Termination
telephone 2) Broadband Connection Unit

Figure 9.14.2 Lightning and surge protection for an ISDN connection with ADSL

www.dehn-international.com LIGHTNING PROTECTION GUIDE 335