WG B1.25 Advanced Design Of Laminated Metallic Coverings

1. WG B1.25 Advanced Design Of Laminated Metallic Coverings Minutes of the First meeting of WG B1-25Paris (Clichy) – 23 & 24 april 20072 pm – 12am

2. Attendee Pierre ARGAUT France Matthias KIRCHNER Germany Bruno FAINARU Israel Giovanni POZZATI Italy Frank MIDDEL Netherlands Bjorn SANDEN Norway Johan KARLSTRAND Sweden Pierre MIREBEAU Convener

3. Agenda

4. Welcome • Each participant presentation • All experts in the group are engineers with more than 5 years experience in the field of High Voltage power cables. • Giovanni Pozzati and Matthias Kirchner were members of the WG 21-14 who made the report for the publication Electra 141 that we have to update. • Secretary designation • All members are cable manufacturers. It is agreed that the group asks for representative of utilities at the next CIGRE B1 meeting (2007). • Meanwhile the convener makes the meeting minutes.

5. Examination of the terms of reference Terms of reference : • To review and update the tests on cables with extruded insulation and laminated protective coverings taking into account the system view, i.e. the installation of accessories. Tests on cable, on accessories and on the system itself should be addressed, including the short circuit one • To issue a Guide to Use for non experts explaining what could be the different cable designs • To issue an Electra paper and a Tutorial. The table of content of the Guide to Use and the Electra paper were not discussed

6. WG B1.25 – Documentation and reports Website • http://www.cigre-b1.org/ • WG area • WG B1-25 • Password : "screen" for reading • pierre.mirebeau@nexans.com

7. Your experience regarding cables with laminated screens - Netherlands • Voltage • Up to 220kV- 2000mm² copper • Prequalificationtest performed at the 380kV level (NL + export) • Design • Insulation system • semi-con swellable tabe , • copper wire screen, • semi-con swellable tape, • aluminium laminated tape 0,2mm, single side coated. • PE outer sheath • In the Netherland lead sheath • Information on the left for export • Reference standard • IEC 60840 • NEN 3630 • Laying conditions • Direct buried. Trefoil formation and flat formation used • Grounding scheme : all schemes

8. Your experience regarding cables with laminated screens - Italy • Voltage • Up to 150kV (EPR used from 1985 to 1990, then XLPE), 220 and 400kV. • All development and prequalificationtest performed • Design • From 1985 to 1990 EPR cables, now XLPE insulation with welded aluminium screen.. • XLPE Insulation system • Semi-conductive water swellable tapes bedding • Welded aluminium screen (1 to 1,2 mm thick) • coating • Polyethylene outer sheath • At the 150kV level, the design Adlmco2 CuAl/Al is also accepted by Terna and Enel, in that case Electra 141 is not required. • Reference standard • IEC 60840 and IEC 62067 + electra 141 • Laying conditions • Direct buried. Trefoil formation and flat formation used (to be checked) • Grounding scheme : single point bonding, solid bonding or cross bonding

9. Your experience regarding cables with laminated screens - France • Voltage • 63kV, 90, 220 and 400kV. Design used since 1989 • All development and prequalificationtest performed • Design • Bedding below the aluminium screen • Mechanical impact 4 times at the same location on the cable 27kg 27cm • Shrink back • Short circuit test conductor and screen with the requested network short circuit level. • Corrosion test 80°C 3000h • Reference standard • NF-C 33 253 (63 & 90 kV) • NF-C 33 254 (225 & 400 kV) • Laying conditions • Directly buried - filled throughs - Mechanical laying - Pulled in PVC or PE ducts • Installed also on bridges • Single point bonded

10. Your experience regarding cables with laminated screens - Israel • Voltage • 161kV ; laminated screen used at the 30kV level • The 400kV network is overhead • Design • In operation • XLPE insulation • Lead sheath • HDPE oversheath • Under development • Flat or round wires screen • One side coated aluminium (0,2 mm thick) or copper (overlap is glued) • For export UK 132kV with .Admlco2 Cu/Cu • Reference standard • IEC 60840 + ICEA S-108-720 • BS 7970 (copper only) • Laying conditions • Flat formation with cross bonding

11. Your experience regarding cables with laminated screens - Germany • Voltage • XLPE insulation, 110, 220, 400kV main experience is at 110kV • Same design for all voltages • More than 20 years feed back • Design • XLPE insulation • Round copper wires to carry all of the short circuit current maximum temperature en of SC : 350°C in case of closed screen, 250°C in case of open screen • Swelling tapes to block the screen area • Al screen 0,2mm + 50µm coating on one side no additional glue at the overlap • MDPE oversheath • "closed screen" : connections in joints and terminations between the wires and the laminate ; "open screen" : contact along the cable between the screen and the laminate. In that case no special connection at the accessories. • Short circuit calculated only with the copper screen - 350°C in case of closed screen - 250°C in case of open screen • Reference standard • VDE 0276 part 632 (110kV) or IEC 60840 & 62067. • No sidewall pressure test, impact nor corrosion test. • Laying conditions • Direct buried cables - Flat formation - Trefoil (also three phases in one big duct) - in tubes • 400kV in tunnel (directly buried to come) - (short circuit tested with joints) • Single point or both ends or cross bonding grounded 

12. Your experience regarding cables with laminated screens - Sweden • Voltage • XLPE insulation, Umax : 52, 145, 245, 420kV • Same design for all voltages • 20 years feed back (1986 in Stockholm) main experience  245 kV • Design • XLPE insulation • Round copper wires screen • Swelling tapes both sides of the screen to block the screen area • Al screen coated on one side 20mm overlap with additional glue • Short circuit calculation without the laminate – 250°C maximum temperature • Lead sheath is rarely used in Sweden • Reference standard • IEC 60840 and 62067 • The Swedish standard is rarely used • Laying conditions • Direct buried cables - Flat formation – Trefoil – Tunnel installation – use of steel or plastic pipes • Cross bonding, single point or both ends grounded 

13. Standards IEC 60840 The Swedish one is rarely used. Your experience regarding cables with laminated screens - Norway • Voltage • XLPE insulation, Umax : 52, 154, 245, 420kV • Same design for all voltages, few number of HV cables • 15 years feed back in HV • Design • XLPE insulation • Round copper wires screen • Swelling tapes both sides of the screen to block the screen area • Al screen coated on one side 20mm overlap with additional glue • Short circuit calculation without the laminate – 250°C maximum temperature • Oversheath : PE or HFFR • Few cases with lead sheath • Reference standard • IEC 60840 and 62067 • Laying conditions • Flat formation - Direct buried cables • Single point or both ends grounded  • Wires and laminates connected at accessories site.

14. Designs There are 3 basic designs used worldwide • Adlmco1 • Used in Italy, France … • XLPE Insulation system • Semi-conductive bedding (swellable if required) • Welded aluminium screen coating • Polyethylene outer sheath • Adlmco2 Cu – Al / Cu – Al • Used in Germany (Adlmco2 Cu/Al), Sweden Sitzerland (Adlmco2 Cu/Cu) … • XLPE insulation • Round copper - wires to carry all of the short circuit current • Swelling tapes to block the screen area • Coated lamonate foil i.e. for example Al screen 0,2mm + 50µm coating on one side no additional glue at the overlap • MDPE oversheath • Adlmco3 • Check with Japan. • To see wether the lead is still used

15. WG B1.25 – What about tests "under development" in WG 21-14 work : moisture penetration • Moisture penetration • The work has been performed in connection with the CIGRE 21-14 group.At the beginning diffusion calculations in Germany, then the quality of the adhesion of the overlap was investigated  peel strength measurement and examination of the overlap area. • What is the actual temperature of the sheath  system view? • There is a test in the Taiwan specification. (Pierre) to be discussed. • There is a test in NL for medium voltage cable.

16. WG B1.25 – What about tests "under development" in WG 21-14 work : Screen contact resistance • Screen contact resistance : • Covered by partial discharges after type test. • See what has been included with CS 9 . and Excelon (Chicago utility) 345kV and 138kV ? • Any method of any need when taking into account the operation feed back ? • Stiffness of the cable

17. WG B1.25 – What about tests "Recommended test" in WG 21-14 work • Thermal load test : • 100 load cycles were recommended by ELECTRA 141. Note that 20 load cycles haves been selected by the IEC TR 61901. • In Italy TERNA asks for the ELECTRA 141 test, depending on the voltage ? • In Sweden development test with 10bars of water pressure on the cable (paper at CIGRE 2002). • In France 250cycles up to 105°C and examination of 250x1m (all voltage levels). There is also the 80 cycles with U bend during the load cycles with an imposed sheath temperature.(to be made once for qualification) • In Germany, after the PQ test observation on a few samples (220 and above), but also carried out for 110kV (one year test 180cycles). • In Norway : not used • In Netherland : not specified • Longitudinal water penetration test • Used everywhere according to IEC requirements

18. WG B1.25 – What about tests "Recommended test" in WG 21-14 work • Impact test: • ELECTRA 141 recommendation : 1m height, 5kg, one impact on each cable location • In France 27kg 27cm 4 times on the same location followed by observation of the laminate and the core. • In Germany Development test with 1m and 5kg weight • In UK height 2m 5kg (JICABLE paper) • Italy : According to Electra 141. • No test in NL, SE, NO. • Short circuit test • ELECTRA 141 recommendation : 5 Short Circuit, Short Circuit time 2sec, up to the screen temperature specified in IEC 986 • In France test at the network short circuit level. 3 Short Circuit • In UK BS = 141 in addition has a spike test (ask whether this test is actually used) • In Italy : According to 141. • No test in DE, NO, SE

19. WG B1.25 – What about tests "Recommended test" in WG 21-14 work • Sidewall pressure test: • ELECTRA 141 recommendation : 750kg/m, 90° • In France no test – (limitation of the pulling force), • Used in Israel with 90° bend • in Sweden used one time during development • In Italy Used with 180° bend, drum fixed + lubricant, and other test for customers (recently 3T/m) • No test in DE, NO, • Corrosion test after impact or sidewall pressure test • ELECTRA 141 recommendation : 70°C, 3000h • In France at 80°C • In Italy at 70°C • In Israel at 70°C • No test in DE, SE, NO, NL

20. WG B1.25 – What about tests "Recommended test" in WG 21-14 work • Peel strength of overlapped metallic foil: • ELECTRA 141 recommendation : sample with 10mm, peel strength > 0,5N.mm (now in IEC 60840 and 62067) • In Germany, Netherlands, Italy, Sweden, Norway : IEC peel strength • in France : Higher peel strength 1.5N/mm • In Israel 1.5N/mm according to BS 7970 (2005)

21. WG B1.25 – What about other tests • System view : • Thermo-mechanical test with accessories in France • Screen fatigue : • CS9 p 67/67 item 14th – fatigue lifetime > 40 years. • Fatigue report of metallic laminates from CCI (BG)

22. WG B1.25 – Guide to use • Screen connection : • Must be welding in case of double end grounding (see Norway experience) • In NL connection of copper wires to the Al screen at each accessory

23. WG B1.25 – Miscellaneous • Standards : • Put the CS9 and the IEEE document on the site and send all attachment to the members. • (CS9 forbid the E141A1-2 design) • ICEA S 108 720 (2004) standard to check. • Japan standard to check • Clarification : • Get clarification about the ICC contribution : • .