International Telecommunication Union Technical Session on Home Networks Geneva, 29/04/2011 ITU-T Study Group 5 Protection against Lightning Phil Day Australia.

International Telecommunication Union

Technical Session onHome Networks

Geneva, 29/04/2011

ITU-T Study Group 5

Protection against Protection against LightningLightning

Phil DayAustralia

ITU-TStudy Group 5

Introduction

o This presentation is about the protection of Home Network (HN) equipment and will specifically cover:• Protection parts• Philosophy of protection• Classification of ports• Mechanisms of damage• Risk

229.04.2011 Technical Session - Home Networks - Geneva

ITU-TStudy Group 5

Introduction (cont)

• Standards• Conclusion


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Protection parts

o Protection of an installation may require a combination of:• Lightning protection of the

building.• Resistibility of equipment.• Protection of incoming lines.• Earthing and bonding of the

installation.


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Protection parts


equipment

a.c. mains

SPD

metallic water pipe

earth electrodes

LPS

main earthingterminal

Telecommunicationcable

Figure 1

SPD

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Protection parts

o Protection of the building structure:• Protection of the building

structure, if necessary, is installed according to the IEC 62305 series.

• It includes a Lightning Protection System (LPS) comprising air terminals, downconductors, equipotential bonding conductors and earth terminations.


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Protection parts

o Resistibility requirements are in Recommendation K.21:• “inherent” and “coordination”

requirement for external ports.• “inherent” requirement for

internal ports.• “basic’ requirement for general

use.• “enhanced’ requirement for

specific reasons.


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Protection parts

• Special requirements where earthing and bonding cannot be achieved.


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Protection parts

o Protection of incoming lines and equipment:• Installation of primary protection

on external lines; mains and external telecommunication or data lines as required.

• Installation of protection at the equipment as required.


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Protection parts

o Earthing and bonding• Earthing is the connection of the

earth bar to earth, usually via an installed earth electrode.

• Bonding is the interconnection of earth electrodes and interconnection of metallic parts to minimise potential differences


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Protection parts (cont)

• SPDs and cable screens are earthed

• IEC 60364-4-44 has the possibility of bonding the PE to the structure earth on each floor to reduce loop sizes


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Philosophy of Protection

o The first method of protection is to install a Multiservice Surge Protective Device (MSPD):• These are described in

Recommendation K.66 (currently called a Combination Protection Unit (CPU).

• They provide equipotential bonding of the ports at the equipment.


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Philosophy of Protection

• They will protect against surges induced into the services and internal wiring, and against conducted surges let through by the primary SPD.


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Philosophy of Protection (cont)

o Power and telecommunication Network operators may install SPDs in lightning prone areas.

o If not, it is recommended that SPDs be installed as required.

o These primary SPDs (telecoms and mains) protect MSPDs, secondary protection and the house wiring.


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Classification of ports

o Equipment can have a combination of internal and external ports:• External ports are protectable by

a GDT on the telecommunications ports and a mains SPD on the mains port. They must comply with a coordination test.


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Classification of ports

• Internal ports require a unique SPD designed according to IEC 61643. There is no coordination test in K.21.

• Guidance on classification of ports is given in K.44 and K.75.

• Incorrect classification may result in damage.


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Mechanisms of damage

o Strike to the structure (S1) may result in damage to external ports (conducted surges) and internal ports (induced surges)

o Strike near to the structure (S2) may result in damage to internal ports (induced surges)


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Mechanisms of damage (cont)

o Strike to the services (S3) may result in damage to external ports (conducted surges) and internal ports (conducted surges). This is the work introduced by NTT. This issue will be studied over the next few months.

o Strike near to the services (S4) may result in damage to external ports (induced surges).


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Practices which may cause damage

o Internal port connected to external cable.

o The interconnected pieces of equipment are connected to different un-bonded electrodes.


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Risk

o Risk is covered in some ITU-T documents but not for damage of customer equipment.

o Risk is also covered in IEC 62305-2, but not for damage of customer equipment.

o Need to consider “loss” versus frequency of damage.


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Risk (cont)

o Recommendation K.hnwr will contain the information for performing a risk assessment and also an example risk assessment.

o The frequency of damage will be determined.


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Relevant Standards

o The following ITU-T documents are relevant.• K.21, K.44, K.66, K.71, K.74, K.75

and K.hnwro The following IEC documents are

relevant• IEC 60364-4-44, IEC 61000-4-5,

IEC 61643 parts 12, 21 and 22 and IEC 62305 series


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Conclusiono If we are to prevent damage to

HN equipment we need:• Adequate resistibility of

equipment.• Correct classification and use of

ports.• Good installation practices.• Correct earthing and bonding.• Protection for external and

internal ports as necessary._________________________________________________


International Telecommunication Union Technical Session on Home Networks Geneva, 29/04/2011 ITU-T Study Group 5 Protection against Lightning Phil Day Australia.

Documents

itut study group

home networks geneva

installation of protection

philosophy of protection

protection parts o earthing

secondary protection

method of protection

spd slide