Question 5/5 - Lightning protection of telecommunication systems
(Continuation of Question 5/5)
Motivation
In recent years, modern society has experienced a high and steady growing dependency on telecommunications. In this context, the reliability of telecommunication services has become an issue of high priority. Operators all over the world are driving efforts in order to assure the reliability of the entire telecommunication system, from the key backbone stations up to the access network. Therefore, the protection against the dangerous effects produced by lightning discharges (high currents associated with strong electromagnetic fields) is a matter of prime concern. This question aims to establish cost-effective engineering procedures in order to allow the telecommunication operators to achieve the desired reliability in their networks.
During the previous study period (2001-2004) some Recommendations for the protection of telecommunication systems against lightning have been developed and other revised. The continuation of this Question aims to revise these and other Recommendations based on new information available, as well as to develop new Recommendations or Chapters of the Lightning Handbook in order to satisfy the identified needs. Close collaboration is to be maintained with IEC TC 81.
The following Recommendations and Handbook, in force at the time of approval of this Question, fall under its responsibility:
K.25, K.29, K.39, K.40, K.46, K.47, K.56 and Lightning Handbook.
Question
The purpose of this Question is to produce new or revised Recommendations or Chapters of the Lightning Handbook regarding the protection of telecommunication systems against the dangerous effects of lightning discharges.
Study items to be considered include, but are not limited to:
- Protection of fixed telecommunications lines, including the lines made of symmetric conductors, coaxial cables and non-metal-free
fibre-optic cables;
- Protection of mobile and wireless systems, in particular radio base stations which very often have their antennas installed in high structures exposed to lightning discharges;
- Protection of telecommunication stations that make part of the network’s backbone and, therefore, require a high reliability;
- Utilization of the data from lighting location system (LP) to optimize the network protection.
Tasks
Tasks include, but are not limited to:
a) Revision of Recommendations K.25 and K.47;
b) Revision of Recommendation K.39 and K.40, regarding the new approach for risk analysis under development by IEC TC 81 and other new technical information available;
c) Revision of Recommendation K.46 regarding the new approach for risk analysis under development by IEC TC 81 and other new information available from experiments with real lines under controlled environment;
d) Revision of Recommendation K.56 regarding new information available from test sites, where validation of K.56 using a real installation and rocket triggered lightning is carried out;
e) New Recommendation on the protection of installations at the neighborhood of telecommunication towers;
f) New recommendation on the use of the data from lighting location system (LP) for network protection;
g) Possible revision and/or edition of additional chapters of the Handbook “Protection of telecommunication lines and equipment against lightning discharges”. Subjects that could be considered are
- Evaluation of shielding factor and the effect of SPD on telecommunication lines (rationale for K.46);
- Evaluation of coupling factors for a radio base station struck by lightning (rationale for K.56);
- Expected overvoltages induced into coaxial cables by direct and indirect lightning discharges (input to resistibility Recommendations K.20, K.21, K.44 and K.45);
- Maximum length of bonding wires of SPDs and requirements for loops formed by the wiring, in order to limit the lightning induced surges (input to K.pcp, see Q 6/5).
Relationships
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Recommendations: K-series
- Questions: 4, 6, 11 and 13/5
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Standardization bodies: IEC TC 81, CENELEC TC 81X, ETSI ERM
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