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Superconducting cables A breakthrough in development. Alex Geschiere Liandon member of Alliander. Alex Geschiere – Netherlands – Session 1 – 1256. Triax cable. Alex Geschiere – Netherlands – Session 1 – Paper 1256. Cryostat design. Stainless steel inner tube
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Superconducting cables A breakthrough in development Alex Geschiere Liandonmember ofAlliander Alex Geschiere – Netherlands – Session 1 – 1256
Triax cable Alex Geschiere – Netherlands – Session 1 – Paper 1256
Cryostat design Stainless steel inner tube Vacuum insulation with multy layer insulation (MLI) Stainless steel outer tube Vacuum: sealed for life. Residual gasses will be absorbed by getter material Alex Geschiere – Netherlands – Session 1 – Paper 1256
Low impedance during Low impedance normal operation Low energy losses Stable voltage profile Low energy losses and High impedance at High impedance high Z increasing current Limiting of short circuit currents Limiting of short circuit very low Z Smart electrical behaviour high Z high Z very low Z very low Z Alex Geschiere – Netherlands – Session 1 – Paper 1256
Temperature profile Challenge: Limit the difference between maximum and minimum temperature in long length cables Alex Geschiere – Netherlands – Session 1 – Paper 1256
Challenge Fault Current Limiting high Z High impedance at High impedance increasing current Limiting of short circuit currents Challenge: Resistive limiting will cause a significant amount of additional heat. Optimize heat management during faults. Limiting of short circuit Alex Geschiere – Netherlands – Session 1 – Paper 1256
Breakthrough in cryostat design Reduced heat leakage in cryostat: - optimize MLI and spacers - mix of straight/rigid sections and corrugated/flexible sections Heat leakage from 1.5 W/m to 0.5 W/m Alex Geschiere – Netherlands – Session 1 – Paper 1256
Low friction design Low friction of Nitrogen mass flow Test of a 45 m low friction cryostat. A mass flow of 0.3 kg/s resulted in a pressure drop of only 5 mbar. Alex Geschiere – Netherlands – Session 1 – Paper 1256
Reduced AC losses AC losses from 1.5 W/m/phase to 0.2 W/m/phase at 3000 Amps • Reduction of gaps between tapes • Narrow HTS tapes will fit the conductor shape better • Special low loss 2G-tapes Alex Geschiere – Netherlands – Session 1 – Paper 1256
Test of reduced AC losses Result form test: AC losses at 3000 Amps of 0.11 W/m/phase (goal 0.2 W/m/phase) Test of three different constructions/tape designs. Huge impact on AC losses. Alex Geschiere – Netherlands – Session 1 – Paper 1256
Significant improvement in development of HTS cables possible in a two years development program. • Results are proved by several tests. alex.geschiere@alliander.com Alex Geschiere – Netherlands – Session 1 – Paper 1256