1. International Telecommunication Union ITU-T Study Group 5 The need for special requirements Tetsuya Tominaga Technical Session on Home Networks Geneva, 29/04/2011

2. ITU-T Study Group 05 AC mains plugs in global o There are many plugs in the world o There is no earth terminal in Japanese type Technical Session - Home Networks - Geneva JAPANESE TYPE

3. ITU-T Study Group 05 Japanese customer premises AC power o Voltage: 100 V rms o Frequency: o 50 Hz Eastern Japan o 60 Hz Western Japan o Configuration: TT Technical Session - Home Networks - Geneva Each PE has each grounding rod

4. ITU-T Study Group 05 Smart House is Connected House 4 7/3/2011 TTC WorkShop SPD Surge Protective Device Optic Fiber Smart Meter Many kinds of equipment will be connected each other under the TT system.

5. ITU-T Study Group 05 Bad installation and insufficient resistibility 5 7/3/2011 TTC WorkShop SPD Surge Protective Device Optic Fiber Smart Meter Good installation and Adequate resistibility are needed.

6. ITU-T Study Group 05 Philosophy of protection 6 7/3/2011 TTC WorkShop SPD SPD Surge Protective Device Optic Fiber SPD Good Bonding (K.66) Additional Protection (K.66) Adequate Resistibility (K.21,K.44,K.66,K.71,K.hnwr) Classification of interface (K.75) Good installation and Adequate resistibility of equipment Who knows K.66? Is Japanese type grounding configuration special?

7. ITU-T Study Group 05 7 7/3/2011 TTC WorkShop Yes No Determine the power induction limits Identify the equipment and the number and type of ports Does the equipment have more than one port type? Enhanced Are there unique problems requiring high isolation values? No Yes Special Basic Are the power induction limits > 600 V? Yes No Figure 1/K.hnwr - Flowchart for determining required level of resistibility Selection for Required resistibility (K.hnwr/Draft) Bad bonding configuration (K.66 For example, the bonding wire length >1.5m ) 5.2 Resistibility Recommendation K.21 has two levels of resistibility basic and enhanced. Specification EN 50468:2009 gives advice on the selection of basic and enhanced. EN 50468:2009 advises: For equipment having only external telecommunication ports the resistibility requirements are defined in ITU-T K.21Basic level. For equipment having additional connections to networks e.g. power networks, the test levels are defined in ITU-T K.21 Enhanced level The required level of resistibility can be determined in Figure 1/K.hnw. Information on Special requirements is contained in K.44. When the bonding configuration is not along with K.66

8. ITU-T Study Group 05 Proposal: Special Resistibility (K.44, K.66,K.hnwr) TEST Telecom municati on line longitudi nal Telecom municati on line transvers e Mains power longitudi nal Mains power transvers e Telecom municati on line – Internal port Mains power – Internal port Telecom municati on line – Mains power line Internal tel. Port – Internal tel. Port Internal tel. Port (L1-L2) Internal Ether Port Internal USB Port Coax. Port Lightnin g Surge Test 13 kV 10/700 4 kV 10/700 10 kV combina tion 13 kV 10/700 10 kV combina tion 13 kV 10/700 10 kV combina tion 10 kV combina tion 4 kV Combin ation Current limit resistor = 50 10kV ?? 6 kV ?? 6.42kA 10/350 K.75 For SPD Technical Session - Home Networks - Geneva Table II.6-1/K.44 – Resistibility and safety requirements of customer premises equipment powered by mains power The special level is already described in K.44 and K.66. The external port is optical fibre now. So, All telecom. Ports are Internal The proposal is adequate Internal port test levels Proposal Under Study

9. ITU-T Study Group 05 Concideration Coordination of protecters and Safety and Lightning protection are important. 9 7/3/2011 TTC WorkShop A N E Un safe method Class II without earthed SPDs A N E Safe method Class II with earthed SPDs Safety and lightning Protection in no earth FUSE Safety = Breaking Fuse Minimize of Damage ratio = No Breaking Fuse SPD2 SPD1 The impedance is need for coordination between SPDs V0 V1 V2 Coordination of protection o Resistibility of inherent ICs or circuit is becoming smaller, so it becomes more difficult to prevent the damage. o No Earth is Un safe?

10. ITU-T Study Group 05 Bypass circuit and Safety standard o Conflict between Safety standards (e.g. IEC 60950) and Lightning protection (Recommendation K.66 and so on). Bypass circuits between AC mains and telecom ports described in K.66 should be permitted in any case to protect telecommunication equipments against overvoltages. The protector operate voltage would be higher than the insulation test voltage. Unfortunately the safety standards, e.g. IEC 60950, do not allow voltage limiters to bridge supplementary insulation, double insulation or reinforced insulation. Technical Session - Home Networks - Geneva TD566 is describe in detail, please read them.

11. ITU-T Study Group 05 11 7/3/2011 TTC WorkShop Conclusion o If we are to prevent damage to HNW equipment we need: Adequate resistibility of equipment Special resistibility of equipment, when the equipment can not be controlled the installation environment. Correct classification and use of ports Good installation practices Correct earthing and bonding Protection for external and internal ports as necessary.