Abstract
Electrical insulation is one of the important factors needed to realize superconducting power apparatuses. Some of the apparatuses have no magnetic field shielding due to the requirement of their construction, where the electrical insulation is exposed to high magnetic fields and/or high mechanical stress as well as cryogenic temperatures. However, electrical characteristics of the composite insulation system of coolant and polymeric film under magnetic field have not been reported even though it is a promising electrical insulation system for superconducting cables. This paper focuses on the effect of magnetic fields on partial discharge breakdown of a composite electrical insulation system of liquid nitrogen and polyethylene film. The experimental results show that the life-time of the film to electrical breakdown becomes shorter as the magnetic field increases up to 1 Tesla. This may be attributed to the change of partial discharge activities caused by the magnetic field.
