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Reducing or turning off the load of a mass-impregnated non-draining cable causes its internal pressure to drop. Under certain conditions, the pressure becomes so low that harmful shrinkage voids or cavities are created in the insulation. The pressure and pressure dynamics of mass-impregnated non...

MgB2 multi-filamentary superconductors are widely considered for use in dc applications. To expand the possible application range to ac apparatuses, the development of a low ac loss wire is needed. This development involves several steps, and a solid understanding of the loss mechanisms is important...

The internal pressures in the insulation of two 5-m long pieces of a state-of-the art mass-impregnated non-draining subsea cable have been measured under load current cycling at ambient temperatures ranging from 3 to 37 °C. Thermal expansion of the mass gives in some cases rather extreme internal...

Ablation-assisted current interruption is a candidate for improving interruption capability in medium voltage switchgear. In high voltage switchgear, ablation is utilized to achieve high pressures in self-blast circuit breakers. Self-blast switch technology adapted to medium voltage could represent...

MgB2 superconductors are considered for generator field coils for direct drive wind turbine generators. In such coils, the losses generated by AC magnetic fields may generate excessive local heating and add to the thermal load, which must be removed by the cooling system. These losses must be...

To realize large (>10 MW) direct-driven off-shore wind turbines, a number of steps are needed to reduce weight and cost compared to on-shore technologies. One of the major challenges is to provide drive trains which can comply with the large torque as the turbine rotor diameter is scaled up and the...

The technology and the operational patterns of HVDC links are changing, and therefore, the type test requirements for mass-impregnated non-draining HVDC cables are currently being reconsidered. A CIGRÉ working group is preparing a revised type test recommendation. Measurements and numerical...

Thermal expansion and contraction of the impregnation oil (the “mass”) in mass-impregnated non-draining HVDC cables cause the internal pressure to vary greatly during load changes. Pressure drops after load turn-off is a concern since formation of shrinkage cavities may reduce the dielectric...

The expected abolishment of SF₆-gas in medium voltage switchgear has prompted a search for replacements for the switch types that depend on SF₆ to obtain the required capability, reliability, compactness and cost. Ablation of polymers can enhance the arc-quenching capabilities in certain electrical...

Generators based on superconducting rotor coils are considered for future large off-shore wind turbines for their low weight and compact design, and for their possibility to reduce costs. In the 10-20 K temperature range, MgB2 superconductors carry current densities 100 times higher than standard...

Mange har tatt i bruk ulike avarter av skjermende luseskjørt, men effekten av dem er varierende. Kunnskapen rundt god bruk med hensyn til lokale forhold er lav, og det er uklart hvilke faktorer som er årsaken til den varierende effekten. I denne artikkelen vil vi belyse effekten av relevante variabler...