Protection against Lightning

1. Protection against Lightning Phil Day Australia

2. Introduction • 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 Technical Session - Home Networks - Geneva

3. Introduction (cont) • Standards • Conclusion Technical Session - Home Networks - Geneva

4. Protection parts • 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

5. LPS equipment SPD SPD Telecommunication cable main earthing terminal a.c. mains earth electrodes metallic water pipe Figure 1 Protection parts Technical Session - Home Networks - Geneva

6. Protection parts • 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. Technical Session - Home Networks - Geneva

7. Protection parts • 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. Technical Session - Home Networks - Geneva

8. Protection parts • Special requirements where earthing and bonding cannot be achieved. Technical Session - Home Networks - Geneva

9. Protection parts • 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. Technical Session - Home Networks - Geneva

10. Protection parts • 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 Technical Session - Home Networks - Geneva

11. 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 Technical Session - Home Networks - Geneva

12. Philosophy of Protection • 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. Technical Session - Home Networks - Geneva

13. 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. Technical Session - Home Networks - Geneva

14. Philosophy of Protection (cont) • Power and telecommunication Network operators may install SPDs in lightning prone areas. • If not, it is recommended that SPDs be installed as required. • These primary SPDs (telecoms and mains) protect MSPDs, secondary protection and the house wiring. Technical Session - Home Networks - Geneva

15. Classification of ports • 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. Technical Session - Home Networks - Geneva

16. 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. Technical Session - Home Networks - Geneva

17. Mechanisms of damage • Strike to the structure (S1) may result in damage to external ports (conducted surges) and internal ports (induced surges) • Strike near to the structure (S2) may result in damage to internal ports (induced surges) Technical Session - Home Networks - Geneva

18. Mechanisms of damage (cont) • 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. • Strike near to the services (S4) may result in damage to external ports (induced surges). Technical Session - Home Networks - Geneva

19. Practices which may cause damage • Internal port connected to external cable. • The interconnected pieces of equipment are connected to different un-bonded electrodes. Technical Session - Home Networks - Geneva

20. Risk • Risk is covered in some ITU-T documents but not for damage of customer equipment. • Risk is also covered in IEC 62305-2, but not for damage of customer equipment. • Need to consider “loss” versus frequency of damage. Technical Session - Home Networks - Geneva

21. Risk (cont) • Recommendation K.hnwr will contain the information for performing a risk assessment and also an example risk assessment. • The frequency of damage will be determined. Technical Session - Home Networks - Geneva

22. Relevant Standards • The following ITU-T documents are relevant. • K.21, K.44, K.66, K.71, K.74, K.75 and K.hnwr • 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

23. Conclusion • 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. _________________________________________________ Technical Session - Home Networks - Geneva