Risk Assessment for Cable Qualifications Combining HV EHV

Risk Assessment for Cable Qualifications Combining HV & EHV Cable Qualifications Understanding the Risk side of the Risk / Benefit Caryn Riley, Josh Perkel, Ray Hill, and Nigel Hampton NEETRAC

Risk Assessment for Cable Qualifications Qualification Landscape • Numerous philosophies & standards may be used to qualify a Transmission Cable System CABLE SYSTEM IEC & AEIC CABLE ACCESSORIES IEC- HV & stress limited ICEA JOINT TERMINATION IEEE 404 IEEE 48 AEIC COMPONENT 2

Risk Assessment for Cable Qualifications Segments of Type Tests IEC & AEIC System Survival Pre Tests • • Load Cycles Number Temperature Time Window Environment Post Tests HV EHV System IEC 60840 Clause 12 IEC 60267 Clause 12 Cable IEC 60840 Clause 13 ICEA 720 Accessories IEC 60840 Clause 14 Water Tests 3

Risk Assessment for Cable Qualifications Temperature Constraints Constraint Number of thermal It is possible to cycles determine a Max Cond Temp n Temp Time / Loc Measurement Temperature Cycle End Temp Recipe that 95 – 100 fulfills these Time in window Any 2 hours requirements Heating Time on the large Cooling Time loop. Conduit required IEC ICEA 20 100 – 105 Hottest Point None Hr 6 to Hr 8 8 hours 16 hours Permited Required 4

Risk Assessment for Cable Qualifications Thermal Profile Impact - ICEA 3000 A 2 step A complicated cycle increases the chance of a “missed” cycle but the system experiences the ageing of the missed cycle 5

Risk Assessment for Cable Qualifications Type Test Architecture – add cable Pre Tests • • Load Cycles Number Temperature Time Window Environment Term Cable Term Post Tests Joint Water Tests 6

Risk Assessment for Cable Qualifications Exposure Min Reliability of Cycles / Time (hrs) of Number Cycle Exposure of Cycles Multiplier On Test IEC / ICEA 20 1. 1 22 / 2 Outcome (@ mid 2015) Mean Component Incident Rate – IEC Test Electrical Established Designs Cable Joint Termination (incl GIS) (%) <5 40 15 WHY • Design Evolutions • Non Robust Qual • lucky pass • reach in “Range of Qual” • Inadequate Training • Workmanship 7

Risk Assessment for Cable Qualifications Architecture Risk Consider survival of component TOTAL RISK 20% TOTAL RISK 36% QUAL RISK 5% CABLE QUAL RISK 10% 85 % 95 % TOTAL RISK 54% CABLE QUAL RISK 10% 60 % 95 % 85 % 8

Risk Assessment for Cable Qualifications Impact of Components on Risk 9

Risk Assessment for Cable Qualifications Recovery needs Planning • Extra Lengths • Extra Components 10

Risk Assessment for Cable Qualifications Conclusions • Engineers like to include many components to maximise coverage. • Successfully completion is by no means guaranteed. • The risks are different for each component type and increases with number. • The more complicated the loop, the higher the risk (generally). • Recovery when components fail is possible but must be built in at the start – Must repeat some or all of the test program depending on what failed and when • Must balance risk with potential benefit 11