ITU-T SG 5 Technical Session Lightning protection 12 December 2005, ITU Headquarters, Geneva ITU-T Technical Session Lightning Protection Highlights & Conclusions Ahmed Zeddam France Telecom

ITU-T SG 5 Technical Session Lightning protection 12 December 2005, ITU Headquarters, Geneva ITU-T Technical Session Lightning Protection Agenda Risk assessment for structure R. Pomponi, Telecom Italia Risk assessment for services A. Zeddam, France Telecom Risk regarding safety P. Day, Telstra Experimental result C. Fonseca Barbosa, CPqD

ITU-T SG 5 Technical Session Lightning protection 12 December 2005, ITU Headquarters, Geneva ITU-T Highlights from Presentation 1 Risk assessment for structures IEC standard gives an exhaustive risk assessment for structures, its contents and connected services This standard should be used for protection need evaluation of the exchange or customers buildings and remote site Critical points: Risk evaluation for loss of service Protection factor P M due to flashes near the structure Necessary clarification and/or improvement: Protection factor values P Z due flashes near the service are missed for 1 kV equipment resistibility P SPD values for SPDs installed on shielded cables Induction loop between two equipment inside the structure is missed

ITU-T SG 5 Technical Session Lightning protection 12 December 2005, ITU Headquarters, Geneva ITU-T Highlights from Presentation 1 Risk assessment for structures IEC standard gives a risk assessment for services following the same approach for structures This standard should be used for protection need evaluation along the service and structures where the service is entering (customers buildings, centres and remote site….) Critical points: Some parameters needed for the risk assessment are till now contained in IEC For the time being, application only to the Telecom line protection (IEC ) Necessary clarification and/or improvement: Shielding factor for internal & external wiring Protection factor values P' Z due flashes near the service are missed for 1 kV equipment resistibility P SPD values for SPDs installed on shielded cables Global approach : service + structure

ITU-T SG 5 Technical Session Lightning protection 12 December 2005, ITU Headquarters, Geneva ITU-T Highlights from Presentation 3 Risk regarding safety Draft IEC is a good basis for the preparation of K.risk and determining the risk associated with a telecommunications service Further work needs to be performed to accurately calculate the risk associated with the introduction of the remote telecommunications earth The factor L c used to determine the collection area needs rationale and validation. It is critical to an accurate calculation The linkage between P X and L X needs to be established and appropriate loss values determined for domestic telecommunications equipment

ITU-T SG 5 Technical Session Lightning protection 12 December 2005, ITU Headquarters, Geneva ITU-T Highlights from Presentation 4 Experimental results Shielding factors and protective effect of SPD applied to telecommunication lines can be assessed from simply equations derived from travelling wave theory. The wave form of current induced into a short circuited loop by lightning is identical to the inducing current. The time derivative of the surge current that flows through a service of an installation struck by lightning is only a few percent of the lightning currents di/dt. The experimental site with rocket triggered lightning of Cachoeira Paulista - Brazil is a relevant source of information in order to revise the existing standards on lightning protection and to develop new ones.

ITU-T SG 5 Technical Session Lightning protection 12 December 2005, ITU Headquarters, Geneva ITU-T Conclusion IEC /TC 81 has recently produced new series of standards on Lightning Protection regarding the structures and services These standards can be used by ITU-T SG 5 for the amendment or development of Recommendations Some clarification and/or improvement are sill necessary, particularly for IEC standard SG5 has relevant source of information based on experimental results in order to revise the existing standards on lightning protection SG5 will continue its liaison with IEC TC 81 in order to improve the knowledge on lightning protection and develop new standards