Technical Session “Lightning Protection” Highlights & Conclusions

1. Technical Session“Lightning Protection”Highlights & Conclusions Ahmed Zeddam France Telecom

2. 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

3. Highlights from Presentation 1“Risk assessment for structures” • IEC 62305-2 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 customer’s buildings and remote site • Critical points: • Risk evaluation for loss of service • Protection factor PM due to flashes near the structure • Necessary clarification and/or improvement: • Protection factor values PZ due flashes near the service are missed for 1 kV equipment resistibility • PSPD values for SPDs installed on shielded cables • Induction loop between two equipment inside the structure is missed

4. Highlights from Presentation 1“Risk assessment for structures” • IEC 62305-2 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 (customer’s buildings, centres and remote site….) • Critical points: • Some parameters needed for the risk assessment are till now contained in IEC 62305-5 • For the time being, application only to the Telecom line protection (IEC 62305-5) • 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 • PSPD values for SPDs installed on shielded cables • Global approach : service + structure

5. Highlights from Presentation 3“Risk regarding safety” • Draft IEC 62305-2 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 Lc used to determine the collection area needs rationale and validation. It is critical to an accurate calculation • The linkage between PX and LX needs to be established and appropriate loss values determined for domestic telecommunications equipment

6. 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 current’s 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.

7. 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 62305-2 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