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 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. It shall also be reminded that lightning discharges may jeopardize the users of telecommunications services if an adequate protection is not provided. This question aims to establish cost-effective engineering procedures in order to allow the telecommunication operators to achieve the desired reliability in their networks, as well as the safety of the customers.

Close collaboration is to be maintained with IEC TC 81, as there has been established a clear boundary on the standards for lightning protection, where SG 5 has got the responsibility for the development of risk assessment and protection techniques for telecommunications services and the resulting recommendations should complement the IEC 62305 series.

This Question impacts climate change issues by ensuring that adequate resistibility requirements for equipment and protective measures for installations reduce the amount of equipment and installation damages. By reducing damages less fossil fuels are burnt (personnel do not have to drive to a site to repair equipment) and less manufacturing is required (less replacement equipment is needed).

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, K.67, K.71, K.72 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 and give guidance on installation and protection of power supply systems for telecommunication installations and equipment outside the central office;

• 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;
• Protection of users of telecommunications services from the dangerous effects of lightning discharges, in collaboration with Question 11/5.

Tasks

Tasks include, but are not limited to:

• Revision of Recommendations K.29 considering the results of experiments carried out using rocket-triggered lightning over buried telecommunications cables with different protection schemes;
• Revision of Recommendation K.39 and K.40, taking into account the IEC 62305 standards;
• Revision of Recommendation K.67 based on new information available on the surges due to lightning.
• 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;
• New Recommendation on the protection of installations at the neighborhood of telecommunication towers;
• New recommendation on the use of the data from lighting location system (LP) for network protection;
• 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.
• Revision of Rec. K.71 based on the experience from its use.

An up-to-date status of work under this Question is contained in the SG 5 Work Program (use URL as shown in the table below).

Relationships

Recommendations:

• K-series

Questions:

• 4, 6, 11 and 13/5

Study Groups:

• none

Standardization bodies:

• IEC TC 81, CENELEC TC 81X, ETSI ERM