International Telecommunication Union ITU-T Study Group 05 The model testing/simulations Yasuhiro Honma Technical Session on Home Networks Geneva, 29/04/2011

ITU-T Study Group 05 Outline o Mechanism of internal ports lightning surge o Experiment and Simulation model o Relation between AC mains lightning surge current and induced Internal port surge voltage/current o Occurrence probability of AC mains surge current o Estimation for relation between Failure rate and test levels o Conclusion Technical Session - Home Networks - Geneva

ITU-T Study Group 05 Mechanism of internal port lightning surge for ONT/HGW Case 2: Damage occurred between two internal ports of telecom equipment Damage: Telecom. Equip 1 (FAX), Home Gate Way & Telecom. equip 2 (PC) Route: AC mains(1) – TE1 -- HGW – TE2 – SPD – Local PE Even fiber optic ONT/HGW equipment, if telecom. equipment is connected to the port which uses AC mains power, the surge voltage is generated during the internal ports.

ITU-T Study Group 05 Overvoltage measured in experimental house model Arrangement I Ent V Phase I Phase The relation ship between I Ent (current flow on entrance point) and V phase /I phase (Induced voltage and current) was examined experimentally

ITU-T Study Group 05 Spice model Technical Session - Home Networks - Geneva V Phase I Phase I Ent ItemsParameter Impedance of power line cable between DB and TE １ R1 = 19 mΩ L1 = 19 uH (Length d1 = 19 m) Impedance of power line cable between DB and TE2 R2 = 3 mΩ L2 = 3 uH (Length d2 = 3 m) Impedance of power line cable between DB and washing machine R3 = 6 mΩ L3 = 6 uH (Length d3 = 6 m) Impedance of washing machiene grouding cable R4 = 6 mΩ L4 = 6 uH (Length d4 = 6 m) Impedance of internal telecommunication cable R5 = 1 Ω L5 = 15 uH (Length d5 = 15 m) Telecommunication equipment 470 V and 270 V. diode An appliance with earthed SPDs 1800 V. diode Loop inductance between phases 60 uH Loop inductance of drop cable 270uH Table 1 Simulated parameters To investigate the effect of wire length, amplitude of entrance point current and so on, the results were compared between the SPICE simulation and experiment

ITU-T Study Group 05 Overvoltage measured in experimental house model Visuals Technical Session - Home Networks - Geneva

ITU-T Study Group 05 Results (1) waveforms Experiment and Simulation Technical Session - Home Networks - Geneva V Phase A V Phase B I Ent V Phase I Phase I Ent

ITU-T Study Group 05 Results (2) Peak values Relation between I Ent and V phase, I phase Technical Session - Home Networks - Geneva I Ent [kA] V phase Voltage [kV] 7.5kA ⇒ 5kV I Ent [kA] I phase Current [A] Figure 1 Relation between I Ent and Vphase

ITU-T Study Group 05 Technical Session - Home Networks - Geneva Lightning current peak value [A] Cumulative occurrence frequency [times/thunder storm day] Measurement period: 3 months. Frequency of currents >1 kA = per thunderstorm day. Frequency of currents >3 kA = per thunderstorm day. J.Kato T.Tominaga et.al, “Measurement results of Lighting surge current on ac mains line connected to access network equipment” EMC’04/Sendai Figure 2 Relation between lightning current peak value and occurrence frequency Observed lightning current on AC mains port

ITU-T Study Group 05 Calculation between Failure rate and Internal ports voltage Technical Session - Home Networks - Geneva (1) Estimation for occurrence probability of I Ent Assuming the Failure rate R FA [%] and the thunderstorm days per year D TS [Day/year], The Occurrence Probability of I Ent is obtained by following equation, From the occurrence probability of I Ent, the maximum current flow on entrance point I Ent is obtained by Figure 2 (2) Estimation for Internal ports voltage of V phase From the expected current flow of I Ent, the expected internal voltage V Phase is obtained by Figure 1

ITU-T Study Group 05 Calculated results; Failure rate and Internal port voltage Technical Session - Home Networks - Geneva 15 thunderstorm days Failure Rare[%] R FA Currents flow on Entrance Point [kA] I Ent Induced voltage [kV] V phase thunderstorm days Failure Rare[%] R FA Currents flow on Entrance Point [kA] I ent Induced voltage [kV] V phase thunderstorm days Failure Rare[%] R FA Currents flow on Entrance Point [kA] I ent Induced voltage [kV] V phase On average 20 thunderstorm days per year 15 million users of optical network equipment in Japan. If the failure rate assumes 0.05 %, the 7500 failures per year will occur.

ITU-T Study Group 05 Consideration on AC mains distribution system Technical Session - Home Networks - Geneva We reported that the lightning overvoltage between the internal ports of telecommunications equipment that used an optical line occurred due to lightning surges from the electric power line in the TT system (Japanese). We also evaluated the lightning overvoltage generated at the internal telecommunication ports for various system earthings. See TD 562:Evaluation of lightning overvoltage at internal telecommunication ports for various system earthings Fig. 14/TD 562 TN-C-S system (case 4) The internal ports voltage may occur.

ITU-T Study Group 05 Overvoltage measured in experimental house model Arrangement I Ent V Phase I Phase The relation ship between I Ent (current flow on entrance point) and V phase /I phase (Induced voltage and current) was examined experimentally

ITU-T Study Group 05 Conclusion o Introduced the mechanism of lightning over- voltage applied between the internal ports for ONT/HGW. o Derived a relationship between the AC mains lightning current and internal ports voltage/current from the experiment and simulation. o Assuming the failure rate is 0.05%, and thunderstorm days is 30 day, the internal ports voltages was estimated, the calculated voltage was almost 10 kV. Technical Session - Home Networks - Geneva