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					    International Telecommunication Union



  ITU-T Study Group 5
Protection against Lightning
            Phil Day
            Australia

     Technical Session on
       Home Networks
     Geneva, 29/04/2011
                            Introduction

ITU-T            o This presentation is about the
 Study Group 5     protection of Home Network (HN)
                   equipment and will specifically
                   cover:
                   • Protection parts
                   • Philosophy of protection
                   • Classification of ports
                   • Mechanisms of damage
                   • Risk

                             Technical Session - Home Networks - Geneva   2
29.04.2011
                     Introduction (cont)

ITU-T
 Study Group 5
                 • Standards
                 • Conclusion




                           Technical Session - Home Networks - Geneva   3
29.04.2011
                          Protection parts

ITU-T
 Study Group 5
                 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.



                             Technical Session - Home Networks - Geneva   4
29.04.2011
                             Protection parts

ITU-T
 Study Group 5
                                    LPS




                                                 equipment




                                          SPD
                                                SPD



                                                                    Telecommunication
                                                                     cable


                                                    main earthing
                 earth electrodes                   terminal           a.c. mains


                                          metallic water pipe



                                    Figure 1

                                     Technical Session - Home Networks - Geneva         5
29.04.2011
                          Protection parts

ITU-T            o Protection of the building structure:
 Study Group 5
                   • 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.


                             Technical Session - Home Networks - Geneva   6
29.04.2011
                          Protection parts

ITU-T            o Resistibility requirements are in
 Study Group 5     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.


                             Technical Session - Home Networks - Geneva   7
29.04.2011
                       Protection parts
                 • Special requirements where earthing
ITU-T              and bonding cannot be achieved.
 Study Group 5




                          Technical Session - Home Networks - Geneva   8
29.04.2011
                         Protection parts

ITU-T            o Protection of incoming lines and
 Study Group 5
                  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.



                             Technical Session - Home Networks - Geneva   9
29.04.2011
                         Protection parts

ITU-T            o Earthing and bonding
 Study Group 5
                   • 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



                            Technical Session - Home Networks - Geneva   10
29.04.2011
                  Protection parts (cont)

ITU-T            • SPDs and cable screens are earthed
 Study Group 5
                 • IEC 60364-4-44 has the possibility of
                   bonding the PE to the structure earth
                   on each floor to reduce loop sizes




                           Technical Session - Home Networks - Geneva   11
29.04.2011
                    Philosophy of Protection

ITU-T            o The first method of protection is to
 Study Group 5
                   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.


                             Technical Session - Home Networks - Geneva   12
29.04.2011
                 Philosophy of Protection

ITU-T            • They will protect against surges
 Study Group 5
                   induced into the services and internal
                   wiring, and against conducted surges
                   let through by the primary SPD.




                           Technical Session - Home Networks - Geneva   13
29.04.2011
                    Philosophy of Protection
                            (cont)
ITU-T            o Power and telecommunication
 Study Group 5
                   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.


                            Technical Session - Home Networks - Geneva   14
29.04.2011
                     Classification of ports

ITU-T            o Equipment can have a combination
 Study Group 5
                  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.




                            Technical Session - Home Networks - Geneva   15
29.04.2011
                   Classification of ports

ITU-T            • Internal ports require a unique SPD
 Study Group 5
                   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.




                           Technical Session - Home Networks - Geneva   16
29.04.2011
                     Mechanisms of damage

ITU-T            o Strike to the structure (S1) may
 Study Group 5
                   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)




                             Technical Session - Home Networks - Geneva   17
29.04.2011
                     Mechanisms of damage
                            (cont)
ITU-T            o Strike to the services (S3) may result
 Study Group 5
                   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).

                             Technical Session - Home Networks - Geneva   18
29.04.2011
                  Practices which may cause
                            damage
ITU-T            o Internal port connected to external
 Study Group 5
                   cable.
                 o The interconnected pieces of
                   equipment are connected to
                   different un-bonded electrodes.




                            Technical Session - Home Networks - Geneva   19
29.04.2011
                                      Risk

ITU-T            o Risk is covered in some ITU-T
 Study Group 5
                   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.


                             Technical Session - Home Networks - Geneva   20
29.04.2011
                             Risk (cont)

ITU-T            o Recommendation K.hnwr will contain
 Study Group 5
                   the information for performing a risk
                   assessment and also an example risk
                   assessment.
                 o The frequency of damage will be
                   determined.




                             Technical Session - Home Networks - Geneva   21
29.04.2011
                       Relevant Standards

ITU-T            o The following ITU-T documents are
 Study Group 5
                  relevant.
                   • K.21, K.44, K.66, K.71, K.74, K.75
                     and K.hnwr
                 o 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

                              Technical Session - Home Networks - Geneva   22
29.04.2011
                                Conclusion
                 o If we are to prevent damage to HN
ITU-T             equipment we need:
 Study Group 5
                   • 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.
                      _________________________________________________




                                Technical Session - Home Networks - Geneva   23
29.04.2011

				
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