ITU-T SG 5 Technical Session “Lightning protection”12 December 2005, ITU Headquarters, Geneva

ITU-TITU-TTechnical Session

“Lightning Protection”

Highlights & Conclusions

Ahmed ZeddamAhmed ZeddamFrance TelecomFrance Telecom

ITU-T SG 5 Technical Session “Lightning protection”12 December 2005, ITU Headquarters, Geneva

ITU-TITU-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-TITU-T

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

ITU-T SG 5 Technical Session “Lightning protection”12 December 2005, ITU Headquarters, Geneva

ITU-TITU-T

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

ITU-T SG 5 Technical Session “Lightning protection”12 December 2005, ITU Headquarters, Geneva

ITU-TITU-T

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

ITU-T SG 5 Technical Session “Lightning protection”12 December 2005, ITU Headquarters, Geneva

ITU-TITU-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 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.

ITU-T SG 5 Technical Session “Lightning protection”12 December 2005, ITU Headquarters, Geneva

ITU-TITU-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 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