International Telecommunication Union ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva Risk regarding safety Phil Day Protection Specialist, Telstra Corp, Australia

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 2 dates Introduction o This presentation will introduce: 1. Missing risk components 2. Risk mechanisms 3. The magnitudes of voltages and currents relevant to electric shock; 4. Discussion on Future work

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 3 dates Lightning as source of damages Direct to the structure Close to the structure Direct to the tlc line Close to the tlc line R A Injury to people R B Physical damage R C Equipment failure R U Injury to people R V Physical damage R W Equipment failure R M Equipment failure R Z Equipment failure R1: Risk of loss of human life = R A +R B +R U +R V +(R C +R W +R M +R Z ) R2: Risk of loss of service = R B +R C +R V +R W +R M +R Z R3: Risk of loss of cultural heritage = R B +R V R4: Risk of loss of economic value = R B +R C +R V +R W +R M +R Z

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 4 dates Missing Risk components o R A is the risk of electric shock component due to a strike to the structure 1.Does not calculate inside structure Note in Remote telecommunication earth is a particular risk and not calculated 3.Following figures show mechanisms

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 5 dates Missing Risk components o R U is the risk of eclectic shock component due to a strike to the services 1.Remote telecommunication earth is a particular risk and not calculated 2.Following figures show mechanisms

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 6 dates Risk mechanisms Figure 3 - Direct strike to structure (touch potential with respect to the ground outside the structure) R A1

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 7 dates Risk mechanisms (cont) Figure 4 - Direct strike to structure (touch potential with respect to the floor of the structure)

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 8 dates Risk mechanisms (cont) Figure 5 - Direct strike to structure (touch potential; earthed object to a telecommunication line which is connected to a remote earth)

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 9 dates Risk mechanisms (cont) Figure 6 - Direct strike to structure (touch potential; floor to a telecommunication line which is connected to a remote earth)

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 10 dates Risk mechanisms (cont) Figure 7 - Direct strike to structure (flashover to internal wiring or plumbing) R B1

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 11 dates Risk mechanisms (cont) Figure 8 - Direct strike to structure (flashover to telecommunication line due to EPR)

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 12 dates Risk mechanisms (cont) Figure 9 - Direct strike to structure (Damage to telecommunication equipment) (No SPDs)

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 13 dates Risk mechanisms (cont) Figure 10 - Direct strike to overhead power line (touch potential with respect to the floor of the structure)

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 14 dates Risk mechanisms (cont) Figure 11 - Direct strike to a power line (touch potential earthed object to the telecommunication line which is connected to a remote earth)

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 15 dates Risk mechanisms (cont) Figure 12 - Direct strike to a power line (touch potential floor to the telecommunication line which is connected to a remote earth)

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 16 dates Risk mechanisms (cont) Figure 13 - Direct strike to telecommunication line (touch potential with respect to the floor of the structure)

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 17 dates Risk mechanisms (cont) Figure 14 - Direct strike to telecommunication line (touch potential with respect to earthed object)

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 18 dates Risk mechanisms (cont) Figure 15 - Direct strike to power line (flashover to telecommunication line due to EPR)

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 19 dates Risk mechanisms (cont) Figure 16 - Direct strike to telecommunication line (flashover to structure)

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 20 dates Risk mechanisms (cont) Figure 17 - Direct strike to power line/cable (Damage to telecommunication equipment)

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 21 dates Risk mechanisms (cont) Figure 18 - Direct strike to telecommunication line/cable (Damage to telecommunication equipment)

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 22 dates Magnitudes Figure 1 - Resistance to ground at strike point

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 23 dates Magnitudes (cont) Figure 2 - EPR at strike point versus current

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 24 dates Magnitudes (cont) Table 1 – Limiting voltage of different cable types Cable limits the voltage (MB = PE sheathed with Moisture Barrier screen; HJ = nylon jacket; PEIFLI = solid PE insulated conductors, grease filled lead-in cable; CPFUT = cellular insulated unit twin conductors;) Cable typeLimiting voltage Cellular (blown) CPFUT MB b/d voltage to screen kV Solid PEIFLI MBHJb/d voltage to screen up to 75 kV Unshielded PE cableb/d voltage to ground up to 150 kV

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 25 dates Magnitudes (cont) Table 2 – Values of r a Low voltages only? Type of soil or floorContact resistance (kΩ)* r a and r u Agricultural, Concrete≤ Marble, Ceramic Gravel, Moquette, Carpets Asphalt, Linoleum, Wood ≥ (*) Values measured between a 400 cm² electrode compressed with a force of 500 N and a point of infinity.

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 26 dates Discussion on o As described by Roberto the Risk of loss = N X * P X * L X 1.N x for services uses L c for the line length. Need to validate values for L c Maybe different for direct strikes versus induction What determines the value of Lc Need consistency for single section versus multiple sections

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 27 dates Discussion on (cont) 1.P x is the probability of damage. This includes: Whether SPDs are installed Shielding factors Screen resistance o Some rationale has been provided by Roberto IEC have assumed both an LPS and coordinated SPDs (software) o My approach is add one at a time. The most common protection is an MSPD and possibly a GDT on the telecommunication line

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 28 dates Discussion on (cont) 1.L x is the consequence of loss. The factors include: n p, n t and t I have difficulty considering these as loss. They relate more to probability In particular r a, r u, r p, r f and h z relate directly to probability of injury or damage There is no loss factor for domestic equipment

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 29 dates Discussion on (cont) Therefore I think SG 5 needs to review the use of loss versus probability If loss is retained the values should be carefully selected and rationale provided Loss factors for domestic equipment need to be developed

ITU-T ITU-T SG 5 Technical Session “Lightning protection” 12 December 2005, ITU Headquarters, Geneva 30 dates Future work o Consider 1. the use of The factor L c 3. The factor r a 4. Loss factors