CIGRE General Session, Paris 2014 Group Meeting SC B1 Insulated Cables, 27th August, 2014 Results of CAG Questionnaire

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1 1 1. Number of Questionnaires Returned Number of suggestions for work Suggestions for new work within the scope of SCB1 or for additional work by current Working Groups in? 3.1 cable system design: 1. Forced cooling systems for greater power capacity in flooded area 2 Armour loss investigation ;Reduce armour losses 3 Normalise/Standardise calculations between system design and cable rating as the math trying to achieve the same answer is slightly different ( contention between cable designs and system designs) 4 Multi cables per phase for high loads( load sharing, X bonding and grounding, maintenance tests, repairs?) 5 Special grounding connections; Cross bonding grounding systems 4 (four) power cables ( 1 circuit and 1 power cable(reservation); Grounding systems with 4 cables, systems cross bonding; SVL earthing and bonding calculations for multiple parallel circuits

2 2 6 More work is needed in the hardware ( cable clamps, supports, etc) for XLPE systems as they could get corroded in wet/watery environment 7 Protection;Optimised armour for large offshore cables 8 For DTS systems: fibre optics inside the cable screen- how to connect it inside or outside the cable joint; 9 Design for mechanically protected cable to facilitate direct installation 3.2 testing 1 Instead of soak test, after installation test 1.7Uo for 60 min; Review test voltage levels on EHV cables;1.7uo for 1 hr testing seems to be questioned. We need to work on this; After installation testing of offshore cables where 1.7Uo is not practically possible. For instance VLF testing of array cables of offshore windfarms;review the 1.7Uo commissioning test in light of 20 years experience, particularly for voltages of ( kV) AC. At the moment test voltage is only 1.2Uo for kV; Study and review factory voltage acceptance test level. These are based on work by Jocteur in which he seeded polymer with metallic particles. With modern clean material is the limit 30kV/mm still valid in determining the voltage.what is the service experience? 2 Standardisation PD an AC field test ;What are acceptable and unacceptable PD quantities in after installation tests

3 3Fire performance CIGRE General Session, Paris Add test protocol for HVDC system considering earth fault condition in terms of polarity reversal 5Infrared image after installation to see hot spots in terminal at the substation or in joints at its boxes 3.3 installation: 1 Long HDD techniques and laying of long cable sections; HDD distances and size; HDD, installation in ducts; Landfall installation for severe conditions. Very long landfall on rollers or very deep and long HDD( for large 3 phase submarine cables) 2 Installing UG HV cables in the ROW of OHTL 3 XLPE cables in the US are installed in duct system causing problems w/ rest of the utilities. Need to work on a system that could provide a mechanical protection but w/o the cons 4 Cable with additional protection for simplified installation testing and approvals 5 Non-destructive methods in the civil infrastructure part of 1? 6 Protection over the submarine cables 7 Study induced voltage in parallel cables for code of practice when jointing on a parallel dead cable 8 Best jointing techniques ; Jointing procedures with regard to joint quality

4 4 3.4 operation 1 Determination if and offshore cable is harmed or not by physical contact with an anchor or likewise 2 Operation of cable systems with and without OHL portions( rules to reclosing power cable systems); Cable systems with and without OHL ( rules to reclosing) 4 How do you monitor temperature variations in existing cables that do not have in-built temperature sensors; Use of temperature and dynamic rating instead of using current for operation; Comparison of calculated ratings versus actual temperature measured 4 Emergency capacity 3.5 maintenance: 1Reparation of long sections(i.e. under river crests,etc 2 Maintenance: of submarine cables- AC and/or DC ; An agreed and approved maintenance strategy (for in-service and spares). Sometimes O&Ms can work when little or no knowledge ;Condition based maintenance (CBM) using diagnostic techniques. It will be good start with HV lines and in next step for HV cables ;Asset mangement of XLPE cable e.g. termination fluid test : PD pass/fail criterion ; DC cables asset mangement e.g can AC techniques apply? does the sheath degarde in the same way? What about XLPE insulation testing ; How to maintain the rare used technologies( manufacture, design, construction, maintenance). Example :OF cables are getting smaller market share - reduction of chances will give the risk to maintain this technology in the future. Is there any action to prevent such risk 3 Fault finding- on long length offshore cable 4 Best practice for different cable types

5 5 5Protection/sinalization against third parties activities 6 Monitoring of terminations on and off shore, specially for ceramic terminations 7 Study methods of monitoring the cable by oversheath monitoring by modern techniques.two papers. Look at methods. One to locate ac failures of primary insulation by unbalanced sheath current and the other by surge voltage- B Gregory 3.6.diagnostic techniques: 1 Fast maintenance diagnosis of partially undergrounded OHL 2 VLF,DAC, variable frequency versus 50Hz testing and diagnostic(pd) 3 Standardised PD and temperature monitoring 4 Tan δ is one of the method of filed insulation testing ; however the devices are hard to find and difficult to perform. We need more work on this one 5 For off shore joints

6 6 3.7 other 1 Measurement methods of XLPE by-products- D1 2 Measurement of cable properties e.g. thermal expansion 3Bring up to date failure frequencies of HV Cables ( internal cause, external cause). The existing brochure uses statistics until Since then a lot of links have been installed and years of operation have passed is in front of us